HID endpoint clarification (feature reports)

[SmallerPond]

I'm trying to wrap my head around the APP_USBD driver, but I'm running into a mental block.  I am implementing a report descriptor for the Battery System usage page, and all of the characteristics are features.  So would I use an in or out endpoint? or both?  I'm in the middle of trying this now and I'm not getting an error, but I'm not seeing the endpoint on the host either - so I'm not sure if this is caused by the endpoint definition or the report.

It has also lead me down a bit of a rabbit hole.  I actually have a composite device with two endpoints working nicely (joystick and keyboard).  When I was adding on this third piece, I remembered that the default keyboard descriptor from the example has an output in it, but there is only an in endpoint.  So this has me feeling like I don't understand what's going on.  Shouldn't there also have to be an out endpoint for the keyboard to get the output from the host?  I thought I would try it, but when I added an out endpoint, the GLOBAL_DEF macro didn't like it and I'm not sure why:

#define HID_KEYBOARD_EPIN       NRF_DRV_USBD_EPIN(2)
#define HID_KEYBOARD_EPOUT       NRF_DRV_USBD_EPOUT(1)

#define ENDPOINT_LIST_KEYBOARD() \
(                           \
        HID_KEYBOARD_EPIN,  \
        HID_KEYBOARD_EPOUT  \
)

APP_USBD_HID_KBD_GLOBAL_DEF(m_app_hid_keyboard,
                            HID_KEYBOARD_INTERFACE,
                            ENDPOINT_LIST_KEYBOARD(),
                            hid_kbd_user_ev_handler,
                            APP_USBD_HID_SUBCLASS_NONE);

gives an "initializer element is not constant" error:

7> Compiling ‘main.c’
7> In file included from ../../../../../../components/libraries/usbd/class/hid/kbd/app_usbd_hid_kbd.h:58,
7>                  from C:\some_path\main.c:96:
7> ../../../../../../components/libraries/usbd/class/hid/kbd/app_usbd_hid_kbd_internal.h:116:1: error: initializer element is not constant
7> ../../../../../../components/libraries/util/app_util.h:712:37: note: in expansion of macro 'APP_USBD_HID_KBD_INTERVAL'
7> ../../../../../../components/libraries/util/nordic_common.h:118:31: note: in expansion of macro 'MACRO_MAP_1'
7> ../../../../../../components/libraries/util/app_util.h:700:29: note: in expansion of macro 'MACRO_MAP_N_'
7> ../../../../../../components/libraries/util/app_util.h:679:25: note: in expansion of macro 'MACRO_MAP_N'
7> ../../../../../../components/libraries/util/app_util.h:678:24: note: in expansion of macro 'MACRO_MAP_'
7> ../../../../../../components/libraries/usbd/class/hid/kbd/app_usbd_hid_kbd_internal.h:167:52: note: in expansion of macro 'MACRO_MAP'
7> ../../../../../../components/libraries/usbd/class/hid/kbd/app_usbd_hid_kbd.h:233:9: note: in expansion of macro 'APP_USBD_HID_KBD_GLOBAL_DEF_INTERNAL'
7> C:\some_path\main.c:619:1: note: in expansion of macro 'APP_USBD_HID_KBD_GLOBAL_DEF'
7> ../../../../../../components/libraries/usbd/class/hid/kbd/app_usbd_hid_kbd_internal.h:116:1: note: (near initialization for 'm_app_hid_keyboard_ep')
7> ../../../../../../components/libraries/util/app_util.h:712:37: note: in expansion of macro 'APP_USBD_HID_KBD_INTERVAL'
7> ../../../../../../components/libraries/util/nordic_common.h:118:31: note: in expansion of macro 'MACRO_MAP_1'
7> ../../../../../../components/libraries/util/app_util.h:700:29: note: in expansion of macro 'MACRO_MAP_N_'
7> ../../../../../../components/libraries/util/app_util.h:679:25: note: in expansion of macro 'MACRO_MAP_N'
7> ../../../../../../components/libraries/util/app_util.h:678:24: note: in expansion of macro 'MACRO_MAP_'
7> ../../../../../../components/libraries/usbd/class/hid/kbd/app_usbd_hid_kbd_internal.h:167:52: note: in expansion of macro 'MACRO_MAP'
7> ../../../../../../components/libraries/usbd/class/hid/kbd/app_usbd_hid_kbd.h:233:9: note: in expansion of macro 'APP_USBD_HID_KBD_GLOBAL_DEF_INTERNAL'
7> C:\some_path\main.c:619:1: note: in expansion of macro 'APP_USBD_HID_KBD_GLOBAL_DEF'
7> In file included from ../../../../../../components/libraries/usbd/app_usbd.h:46,
7>                  from C:\some_path\main.c:92:
7> ../../../../../../components/libraries/usbd/app_usbd_class_base.h:463:18: error: initializer element is not constant
7> ../../../../../../components/libraries/util/app_util.h:747:41: note: in expansion of macro 'APP_USBD_CLASS_IFACE_EP_EXTRACT_1__'
7> ../../../../../../components/libraries/util/nordic_common.h:118:31: note: in expansion of macro 'MACRO_MAP_REC_1'
7> ../../../../../../components/libraries/util/app_util.h:708:33: note: in expansion of macro 'MACRO_MAP_REC_N_'
7> ../../../../../../components/libraries/util/app_util.h:687:29: note: in expansion of macro 'MACRO_MAP_REC_N'
7> ../../../../../../components/libraries/util/app_util.h:686:28: note: in expansion of macro 'MACRO_MAP_REC_'
7> ../../../../../../components/libraries/usbd/app_usbd_class_base.h:460:17: note: in expansion of macro 'MACRO_MAP_REC'
7> ../../../../../../components/libraries/usbd/app_usbd_class_base.h:457:17: note: in expansion of macro 'APP_USBD_CLASS_IFACE_EP_EXTRACT_1_'
7> ../../../../../../components/libraries/util/nordic_common.h:118:31: note: in expansion of macro 'APP_USBD_CLASS_IFACE_EP_EXTRACT_1'
7> ../../../../../../components/libraries/util/nordic_common.h:116:31: note: in expansion of macro 'CONCAT_2_'
7> ../../../../../../components/libraries/usbd/app_usbd_class_base.h:440:9: note: in expansion of macro 'CONCAT_2'
7> ../../../../../../components/libraries/util/app_util.h:712:37: note: in expansion of macro 'APP_USBD_CLASS_IFACE_EP_EXTRACT_'
7> ../../../../../../components/libraries/util/nordic_common.h:118:31: note: in expansion of macro 'MACRO_MAP_1'
7> ../../../../../../components/libraries/util/app_util.h:700:29: note: in expansion of macro 'MACRO_MAP_N_'
7> ../../../../../../components/libraries/util/app_util.h:679:25: note: in expansion of macro 'MACRO_MAP_N'
7> ../../../../../../components/libraries/util/app_util.h:678:24: note: in expansion of macro 'MACRO_MAP_'
7> ../../../../../../components/libraries/usbd/app_usbd_class_base.h:583:5: note: in expansion of macro 'MACRO_MAP'
7> ../../../../../../components/libraries/usbd/app_usbd_class_base.h:811:29: note: in expansion of macro 'APP_USBD_CLASS_IFACES_EP_EXTRACT'
7> ../../../../../../components/libraries/usbd/app_usbd_class_base.h:946:9: note: in expansion of macro 'APP_USBD_CLASS_INSTANCE_INITVAL'
7> ../../../../../../components/libraries/usbd/class/hid/kbd/app_usbd_hid_kbd_internal.h:169:5: note: in expansion of macro 'APP_USBD_CLASS_INST_GLOBAL_DEF'
7> ../../../../../../components/libraries/usbd/class/hid/kbd/app_usbd_hid_kbd.h:233:9: note: in expansion of macro 'APP_USBD_HID_KBD_GLOBAL_DEF_INTERNAL'
7> C:\some_path\main.c:619:1: note: in expansion of macro 'APP_USBD_HID_KBD_GLOBAL_DEF'
7> ../../../../../../components/libraries/usbd/app_usbd_class_base.h:463:18: note: (near initialization for 'm_app_hid_keyboard.specific.iface.ep[0].address')
7> ../../../../../../components/libraries/util/app_util.h:747:41: note: in expansion of macro 'APP_USBD_CLASS_IFACE_EP_EXTRACT_1__'
7> ../../../../../../components/libraries/util/nordic_common.h:118:31: note: in expansion of macro 'MACRO_MAP_REC_1'
7> ../../../../../../components/libraries/util/app_util.h:708:33: note: in expansion of macro 'MACRO_MAP_REC_N_'
7> ../../../../../../components/libraries/util/app_util.h:687:29: note: in expansion of macro 'MACRO_MAP_REC_N'
7> ../../../../../../components/libraries/util/app_util.h:686:28: note: in expansion of macro 'MACRO_MAP_REC_'
7> ../../../../../../components/libraries/usbd/app_usbd_class_base.h:460:17: note: in expansion of macro 'MACRO_MAP_REC'
7> ../../../../../../components/libraries/usbd/app_usbd_class_base.h:457:17: note: in expansion of macro 'APP_USBD_CLASS_IFACE_EP_EXTRACT_1_'
7> ../../../../../../components/libraries/util/nordic_common.h:118:31: note: in expansion of macro 'APP_USBD_CLASS_IFACE_EP_EXTRACT_1'
7> ../../../../../../components/libraries/util/nordic_common.h:116:31: note: in expansion of macro 'CONCAT_2_'
7> ../../../../../../components/libraries/usbd/app_usbd_class_base.h:440:9: note: in expansion of macro 'CONCAT_2'
7> ../../../../../../components/libraries/util/app_util.h:712:37: note: in expansion of macro 'APP_USBD_CLASS_IFACE_EP_EXTRACT_'
7> ../../../../../../components/libraries/util/nordic_common.h:118:31: note: in expansion of macro 'MACRO_MAP_1'
7> ../../../../../../components/libraries/util/app_util.h:700:29: note: in expansion of macro 'MACRO_MAP_N_'
7> ../../../../../../components/libraries/util/app_util.h:679:25: note: in expansion of macro 'MACRO_MAP_N'
7> ../../../../../../components/libraries/util/app_util.h:678:24: note: in expansion of macro 'MACRO_MAP_'
7> ../../../../../../components/libraries/usbd/app_usbd_class_base.h:583:5: note: in expansion of macro 'MACRO_MAP'
7> ../../../../../../components/libraries/usbd/app_usbd_class_base.h:811:29: note: in expansion of macro 'APP_USBD_CLASS_IFACES_EP_EXTRACT'
7> ../../../../../../components/libraries/usbd/app_usbd_class_base.h:946:9: note: in expansion of macro 'APP_USBD_CLASS_INSTANCE_INITVAL'
7> ../../../../../../components/libraries/usbd/class/hid/kbd/app_usbd_hid_kbd_internal.h:169:5: note: in expansion of macro 'APP_USBD_CLASS_INST_GLOBAL_DEF'
7> ../../../../../../components/libraries/usbd/class/hid/kbd/app_usbd_hid_kbd.h:233:9: note: in expansion of macro 'APP_USBD_HID_KBD_GLOBAL_DEF_INTERNAL'
7> C:\some_path\main.c:619:1: note: in expansion of macro 'APP_USBD_HID_KBD_GLOBAL_DEF'
Build failed

which I don't understand.  How could it not be constant?  I got the endpoints the same way I did when there was only one of them.

Anyway, I think maybe I have asked too many questions here, but I'm not 100% if I'm asking the right things so I'm hoping that there is an answer that kind of gets everything since they are related.  If this is wrong, I can always break this into different questions.  Then I can also make another one for my confusion about what the interface parameter does... :-P

[ovrebekk]

Hi

What does your report descriptor look like?

Is it based on the one in the USB HID Usage Table document?

Feature and out reports can use either an output interrupt endpoint or the control endpoint. The control endpoint is always present, so technically no OUT endpoint is needed, which is why the keyboard descriptor can support output reports without configuring an OUT endpoint. 

Best regards
Torbjørn

[SmallerPond]

The report is based on the usage table doc for HID power devices (cf. the chapter on Battery System and the example in Appendix A here, especially section A.6.9).  Generally, I am doing okay with creating descriptors I think.  I'm just a little fuzzy on getting and setting them using the app_usbd driver, and what the interplay is between endpoints, interfaces, and descriptors in the actual implementation.  Here is the descriptor, I can either use it at its own endpoint, or include it as a on the joystick or keyboard descriptor (I think, no?):

#define HID_BATT_REPORT_DESC() {  \
    0x05, 0x85,                    /* USAGE_PAGE (Battery System) */ \
 \
    0x09, 0x18,                    /* USAGE (BatteryInsertion) */ \
    0x75, 0x01,                    /* REPORT_SIZE (1) */ \
    0x95, 0x01,                    /* REPORT_COUNT (1) */ \
    0x15, 0x00,                    /* LOGICAL_MINIMUM (0) */ \
    0x25, 0x01,                    /* LOGICAL_MAXIMUM (1) */ \
    0xb1, 0x03,                    /* FEATURE (Cnst,Var,Abs) */ \
 \
    0x09, 0x2c,                    /* USAGE (CapacityMode) */ \
    0x75, 0x01,                    /* REPORT_SIZE (1) */ \
    0x95, 0x01,                    /* REPORT_COUNT (1) */ \
    0xb1, 0x03,                    /* FEATURE (Cnst,Var,Abs) */ \
 \
    0x75, 0x06,                    /* REPORT_SIZE (6) */ \
    0x95, 0x01,                    /* REPORT_COUNT (1) */ \
    0xb1, 0x03,                    /* FEATURE (Cnst,Var,Abs)  ; end byte 1 */ \
 \
    0x09, 0x83,                    /* USAGE (DesignCapacity) */ \
    0x75, 0x18,                    /* REPORT_SIZE (24) */ \
    0x95, 0x01,                    /* REPORT_COUNT (1) */ \
    0x67, 0x01, 0x10, 0x10, 0x00,  /* UNIT (SI Lin:Battery Capacity) */ \
    0x55, 0x00,                    /* UNIT_EXPONENT (0) */ \
    0x15, 0x00,                    /* LOGICAL_MINIMUM (0) */ \
    0x27, 0xfe, 0xff, 0xff, 0x00,  /* LOGICAL_MAXIMUM (16777214) */ \
    0xb1, 0x03,                    /* FEATURE (Cnst,Var,Abs)  ; end byte 1 + 3 = 4 */ \
 \
    0x09, 0x66,                    /* USAGE (RemainingCapacity) */ \
    0x75, 0x24,                    /* REPORT_SIZE (36) */ \
    0x95, 0x01,                    /* REPORT_COUNT (1) */ \
    0x67, 0x01, 0x10, 0x10, 0x00,  /* UNIT (SI Lin:Battery Capacity) */ \
    0x55, 0x00,                    /* UNIT_EXPONENT (0) */ \
    0xb1, 0x03,                    /* FEATURE (Cnst,Var,Abs)  ; end byte 4 + 4 = 8, start byte 9 with 4 bits */ \
 \
    0x75, 0x04,                    /* REPORT_SIZE (4) */ \
    0x95, 0x01,                    /* REPORT_COUNT (1) */ \
    0xb1, 0x03,                    /* FEATURE (Cnst,Var,Abs)  ; end byte 9 */ \
 \
    0x09, 0x42,                    /* USAGE (BelowRemainingCapacityLimit) */ \
    0x09, 0x44,                    /* USAGE (Charging) */ \
    0x09, 0x45,                    /* USAGE (Discharging) */ \
    0x75, 0x01,                    /* REPORT_SIZE (1) */ \
    0x95, 0x03,                    /* REPORT_COUNT (3) */ \
    0x15, 0x00,                    /* LOGICAL_MINIMUM (0) */ \
    0x25, 0x01,                    /* LOGICAL_MAXIMUM (1) */ \
    0x65, 0x00,                    /* UNIT (None) */ \
    0xb1, 0x03,                    /* FEATURE (Cnst,Var,Abs)  ; start byte 10 with 3 bits */ \
 \
    0x75, 0x05,                    /* REPORT_SIZE (5) */ \
    0x95, 0x01,                    /* REPORT_COUNT (1) */ \
    0xb1, 0x03                     /* FEATURE (Cnst,Var,Abs)  ; +5bits = end byte 10 */ \
}

As I said before, I try to give it it's own endpoint, but I get an error using the macro APP_USBD_HID_KBD_GLOBAL_DEF.  The most important information first is to know what is the preferred way to set up a report descriptor like this one?

Then, once I get it setup without throwing errors, I have no idea how to set the feature reports (I found this for BLE HID, but nothing for USBD) so some information about that would be appreciated.  Finally, if you are feeling particularly generous, maybe you could also clear up for me why I might use a separate endpoint for a new report descriptor vs just trying to append it to an existing descriptor?  Is it just if I plan on updating the data separately?

Thanks for your help!

[Alberto Favero]

Thanks,

did you get any example?

Best regards,

Alberto

[Alberto Favero]

I tried to modified the ble_hids.c/h module because otherwise is not possible to add a second hids_init() interface to the system. The connection became unstable.

Do you have any ideas to open a HID - BLE - 64byte end-point communication with the device?

Thanks,

Alberto

[Alberto Favero]

https://devzone.nordicsemi.com/f/nordic-q-a/42188/increasing-number-of-bytes-in-hid-descriptor

I hope that I found the solution for BLE hid keyboard example and increase endpoint out len to reach 64 bytes.

I post here all the diff:

//#define NRF_SDH_BLE_GATT_MAX_MTU_SIZE 23

#define NRF_SDH_BLE_GATT_MAX_MTU_SIZE 96

 //       0x95, 0x02,       // Report Count (2)

0x95, 0x14,       // Report Count (20) //was Report Count (2)

//uint8_t  report_val;

uint8_t  report_val[64];

//STATIC_ASSERT(OUTPUT_REPORT_MAX_LEN == 20); // was == 1)

//#define OUTPUT_REPORT_MAX_LEN               1 

#define OUTPUT_REPORT_MAX_LEN               64

Is this all correct?

Now is working in linux (ubuntu) with:

sudo ./hidapitester  --open-path /dev/hidraw3 --length 0 --send-output 0X1C,0X00,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2

The data reach the Nordic NRF52840 with the softdevice S140.

Best regards,

Alberto

[ovrebekk]

Hi Alberto

Thanks for the update. 

You mean to say that everything else in the example is identical to the ble_app_hids_keyboard example except for the changes you listed here?

Best regards
Torbjørn

[Alberto Favero]

Exaclty,

I would like to know if everything is of according to the possible modification of the example.

Best regards,

Alberto

[ovrebekk]

Hi 

Correct me if I'm wrong, but you must have made more changes to the main file than the ones you listed in your reply?

For instance, if you change report_val from a uint8_t to a uint8_t array, you would need to make more changes to the code further on. 

Are you able to share your main.c file with me, so I can review all the changes?

If you want I can make this case private, so that the files you share will not be available publicly.

Best regards
Torbjørn

[Alberto Favero]

I simply add the dump of the memory of the array with the function

NRF_LOG_HEXDUMP_INFO

That's all.

Best regards,

Alberto

[ovrebekk]

Hi Alberto

If those are all the changes you made I don't understand how you get the example to work. 

As I said earlier, once you change report_val from a single uint8_t variable to an array you will need to make several more changes other places in the example. 

Without having a look at the whole file it is difficult to say if the changes are OK. 

Ok, now I get it. You mean to say you don't do any other processing of the data, you simply print it to the log?

Best regards
Torbjørn

[Alberto Favero]

Hi,

i will put here the code to edit the example. Have not been easy toe check if ubuntu linux 20.04 and windows 10 work porprely.

I edit also other stuff. Please, check if every think is correct.

I tested the endpoint out in Ubuntu:

sudo ./hidapitester  --open-path /dev/hidraw1 --length 0 --send-output 0X99,0x98,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2

THE EDIT OF THE FILES.

file ble_app_hids_keyboard_gcc_nrf52.ld, extended the size of the ram, to don't have any worrys about it.

  RAM (rwx) :  ORIGIN = 0x20007d00, LENGTH = 0x38300

file sdk_config.h , i need space for the packet (endpoint out)

// <o> NRF_SDH_BLE_GATT_MAX_MTU_SIZE - Static maximum MTU size. 
#ifndef NRF_SDH_BLE_GATT_MAX_MTU_SIZE
#define NRF_SDH_BLE_GATT_MAX_MTU_SIZE 247//23 //250//247 //was 23
#endif

At least, main.c the edit. Several point and at the end the dump of the memory for debug!

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/** @file
 *
 * @defgroup ble_sdk_app_hids_keyboard_main main.c
 * @{
 * @ingroup ble_sdk_app_hids_keyboard
 * @brief HID Keyboard Sample Application main file.
 *
 * This file contains is the source code for a sample application using the HID, Battery and Device
 * Information Services for implementing a simple keyboard functionality.
 * Pressing Button 0 will send text 'hello' to the connected peer. On receiving output report,
 * it toggles the state of LED 2 on the mother board based on whether or not Caps Lock is on.
 * This application uses the @ref app_scheduler.
 *
 * Also it would accept pairing requests from any peer device.
 */

#include <stdint.h>
#include <string.h>
#include "nordic_common.h"
#include "nrf.h"
#include "nrf_assert.h"
#include "app_error.h"
#include "ble.h"
#include "ble_err.h"
#include "ble_hci.h"
#include "ble_srv_common.h"
#include "ble_advertising.h"
#include "ble_advdata.h"
#include "ble_hids.h"
#include "ble_bas.h"
#include "ble_dis.h"
#include "ble_conn_params.h"
#include "sensorsim.h"
#include "bsp_btn_ble.h"
#include "app_scheduler.h"
#include "nrf_sdh.h"
#include "nrf_sdh_soc.h"
#include "nrf_sdh_ble.h"
#include "app_timer.h"
#include "peer_manager.h"
#include "fds.h"
#include "ble_conn_state.h"
#include "nrf_ble_gatt.h"
#include "nrf_ble_qwr.h"
#include "nrf_pwr_mgmt.h"
#include "peer_manager_handler.h"

#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"

/*
To test the example:
sudo ./hidapitester  --open-path /dev/hidraw3 --length 0 --send-output 0X1C,0X00,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2
*/

#define SHIFT_BUTTON_ID                     1                                          /**< Button used as 'SHIFT' Key. */

#define DEVICE_NAME                         "Nordic_Keyboard_64byte"                   /**< Name of device. Will be included in the advertising data. */
#define MANUFACTURER_NAME                   "NordicSemiconductor"                      /**< Manufacturer. Will be passed to Device Information Service. */

#define APP_BLE_OBSERVER_PRIO               3                                          /**< Application's BLE observer priority. You shouldn't need to modify this value. */
#define APP_BLE_CONN_CFG_TAG                1                                          /**< A tag identifying the SoftDevice BLE configuration. */

#define BATTERY_LEVEL_MEAS_INTERVAL         APP_TIMER_TICKS(2000)                      /**< Battery level measurement interval (ticks). */
#define MIN_BATTERY_LEVEL                   81                                         /**< Minimum simulated battery level. */
#define MAX_BATTERY_LEVEL                   100                                        /**< Maximum simulated battery level. */
#define BATTERY_LEVEL_INCREMENT             1                                          /**< Increment between each simulated battery level measurement. */

#define PNP_ID_VENDOR_ID_SOURCE             0x02                                       /**< Vendor ID Source. */
#define PNP_ID_VENDOR_ID                    0x1915                                     /**< Vendor ID. */
#define PNP_ID_PRODUCT_ID                   0xEEEE                                     /**< Product ID. */
#define PNP_ID_PRODUCT_VERSION              0x0002                                     /**< Product Version. */

#define APP_ADV_FAST_INTERVAL               0x0028                                     /**< Fast advertising interval (in units of 0.625 ms. This value corresponds to 25 ms.). */
#define APP_ADV_SLOW_INTERVAL               0x0C80                                     /**< Slow advertising interval (in units of 0.625 ms. This value corrsponds to 2 seconds). */

#define APP_ADV_FAST_DURATION               3000                                       /**< The advertising duration of fast advertising in units of 10 milliseconds. */
#define APP_ADV_SLOW_DURATION               18000                                      /**< The advertising duration of slow advertising in units of 10 milliseconds. */


/*lint -emacro(524, MIN_CONN_INTERVAL) // Loss of precision */
#define MIN_CONN_INTERVAL                   MSEC_TO_UNITS(7.5, UNIT_1_25_MS)           /**< Minimum connection interval (7.5 ms) */
#define MAX_CONN_INTERVAL                   MSEC_TO_UNITS(30, UNIT_1_25_MS)            /**< Maximum connection interval (30 ms). */
#define SLAVE_LATENCY                       6                                          /**< Slave latency. */
#define CONN_SUP_TIMEOUT                    MSEC_TO_UNITS(430, UNIT_10_MS)             /**< Connection supervisory timeout (430 ms). */

#define FIRST_CONN_PARAMS_UPDATE_DELAY      APP_TIMER_TICKS(5000)                      /**< Time from initiating event (connect or start of notification) to first time sd_ble_gap_conn_param_update is called (5 seconds). */
#define NEXT_CONN_PARAMS_UPDATE_DELAY       APP_TIMER_TICKS(30000)                     /**< Time between each call to sd_ble_gap_conn_param_update after the first call (30 seconds). */
#define MAX_CONN_PARAMS_UPDATE_COUNT        5                                          /**< Number of attempts before giving up the connection parameter negotiation. */

#define SEC_PARAM_BOND                      1                                          /**< Perform bonding. */
#define SEC_PARAM_MITM                      0                                          /**< Man In The Middle protection not required. */
#define SEC_PARAM_LESC                      0                                          /**< LE Secure Connections not enabled. */
#define SEC_PARAM_KEYPRESS                  0                                          /**< Keypress notifications not enabled. */
#define SEC_PARAM_IO_CAPABILITIES           BLE_GAP_IO_CAPS_NONE                       /**< No I/O capabilities. */
#define SEC_PARAM_OOB                       0                                          /**< Out Of Band data not available. */
#define SEC_PARAM_MIN_KEY_SIZE              7                                          /**< Minimum encryption key size. */
#define SEC_PARAM_MAX_KEY_SIZE              16                                         /**< Maximum encryption key size. */

#define OUTPUT_REPORT_INDEX                 0                                          /**< Index of Output Report. */
#define OUTPUT_REPORT_MAX_LEN               64 //was 1                                 /**< Maximum length of Output Report. */
#define INPUT_REPORT_KEYS_INDEX             0                                          /**< Index of Input Report. */
#define OUTPUT_REPORT_BIT_MASK_CAPS_LOCK    0x02                                       /**< CAPS LOCK bit in Output Report (based on 'LED Page (0x08)' of the Universal Serial Bus HID Usage Tables). */
#define INPUT_REP_REF_ID                    0                                          /**< Id of reference to Keyboard Input Report. */
#define OUTPUT_REP_REF_ID                   0                                          /**< Id of reference to Keyboard Output Report. */
#define FEATURE_REP_REF_ID                  0                                          /**< ID of reference to Keyboard Feature Report. */
#define FEATURE_REPORT_MAX_LEN              2                                          /**< Maximum length of Feature Report. */
#define FEATURE_REPORT_INDEX                0                                          /**< Index of Feature Report. */

#define MAX_BUFFER_ENTRIES                  5                                          /**< Number of elements that can be enqueued */

#define BASE_USB_HID_SPEC_VERSION           0x0101                                     /**< Version number of base USB HID Specification implemented by this application. */

#define INPUT_REPORT_KEYS_MAX_LEN           8                                          /**< Maximum length of the Input Report characteristic. */

#define DEAD_BEEF                           0xDEADBEEF                                 /**< Value used as error code on stack dump, can be used to identify stack location on stack unwind. */

#define SCHED_MAX_EVENT_DATA_SIZE           APP_TIMER_SCHED_EVENT_DATA_SIZE            /**< Maximum size of scheduler events. */
#ifdef SVCALL_AS_NORMAL_FUNCTION
#define SCHED_QUEUE_SIZE                    20                                         /**< Maximum number of events in the scheduler queue. More is needed in case of Serialization. */
#else
#define SCHED_QUEUE_SIZE                    10                                         /**< Maximum number of events in the scheduler queue. */
#endif

#define MODIFIER_KEY_POS                    0                                          /**< Position of the modifier byte in the Input Report. */
#define SCAN_CODE_POS                       2                                          /**< The start position of the key scan code in a HID Report. */
#define SHIFT_KEY_CODE                      0x02                                       /**< Key code indicating the press of the Shift Key. */

#define MAX_KEYS_IN_ONE_REPORT              (INPUT_REPORT_KEYS_MAX_LEN - SCAN_CODE_POS)/**< Maximum number of key presses that can be sent in one Input Report. */


/**Buffer queue access macros
 *
 * @{ */
/** Initialization of buffer list */
#define BUFFER_LIST_INIT()     \
    do                         \
    {                          \
        buffer_list.rp    = 0; \
        buffer_list.wp    = 0; \
        buffer_list.count = 0; \
    } while (0)

/** Provide status of data list is full or not */
#define BUFFER_LIST_FULL() \
    ((MAX_BUFFER_ENTRIES == buffer_list.count - 1) ? true : false)

/** Provides status of buffer list is empty or not */
#define BUFFER_LIST_EMPTY() \
    ((0 == buffer_list.count) ? true : false)

#define BUFFER_ELEMENT_INIT(i)                 \
    do                                         \
    {                                          \
        buffer_list.buffer[(i)].p_data = NULL; \
    } while (0)

/** @} */

/** Abstracts buffer element */
typedef struct hid_key_buffer
{
    uint8_t      data_offset; /**< Max Data that can be buffered for all entries */
    uint8_t      data_len;    /**< Total length of data */
    uint8_t    * p_data;      /**< Scanned key pattern */
    ble_hids_t * p_instance;  /**< Identifies peer and service instance */
} buffer_entry_t;

STATIC_ASSERT(sizeof(buffer_entry_t) % 4 == 0);

/** Circular buffer list */
typedef struct
{
    buffer_entry_t buffer[MAX_BUFFER_ENTRIES]; /**< Maximum number of entries that can enqueued in the list */
    uint8_t        rp;                         /**< Index to the read location */
    uint8_t        wp;                         /**< Index to write location */
    uint8_t        count;                      /**< Number of elements in the list */
} buffer_list_t;

STATIC_ASSERT(sizeof(buffer_list_t) % 4 == 0);


APP_TIMER_DEF(m_battery_timer_id);                                  /**< Battery timer. */
BLE_HIDS_DEF(m_hids,                                                /**< Structure used to identify the HID service. */
             NRF_SDH_BLE_TOTAL_LINK_COUNT,
             INPUT_REPORT_KEYS_MAX_LEN,
             OUTPUT_REPORT_MAX_LEN,
             FEATURE_REPORT_MAX_LEN);
BLE_BAS_DEF(m_bas);                                                 /**< Structure used to identify the battery service. */
NRF_BLE_GATT_DEF(m_gatt);                                           /**< GATT module instance. */
NRF_BLE_QWR_DEF(m_qwr);                                             /**< Context for the Queued Write module.*/
BLE_ADVERTISING_DEF(m_advertising);                                 /**< Advertising module instance. */

static bool              m_in_boot_mode = false;                    /**< Current protocol mode. */
static uint16_t          m_conn_handle  = BLE_CONN_HANDLE_INVALID;  /**< Handle of the current connection. */
static sensorsim_cfg_t   m_battery_sim_cfg;                         /**< Battery Level sensor simulator configuration. */
static sensorsim_state_t m_battery_sim_state;                       /**< Battery Level sensor simulator state. */
static bool              m_caps_on = false;                         /**< Variable to indicate if Caps Lock is turned on. */
static pm_peer_id_t      m_peer_id;                                 /**< Device reference handle to the current bonded central. */
static buffer_list_t     buffer_list;                               /**< List to enqueue not just data to be sent, but also related information like the handle, connection handle etc */

static ble_uuid_t m_adv_uuids[] = {{BLE_UUID_HUMAN_INTERFACE_DEVICE_SERVICE, BLE_UUID_TYPE_BLE}};

static uint8_t m_sample_key_press_scan_str[] = /**< Key pattern to be sent when the key press button has been pushed. */
{
    0x0b,       /* Key h */
    0x08,       /* Key e */
    0x0f,       /* Key l */
    0x0f,       /* Key l */
    0x12,       /* Key o */
    0x28        /* Key Return */
};

static uint8_t m_caps_on_key_scan_str[] = /**< Key pattern to be sent when the output report has been written with the CAPS LOCK bit set. */
{
    0x06,       /* Key C */
    0x04,       /* Key a */
    0x13,       /* Key p */
    0x16,       /* Key s */
    0x12,       /* Key o */
    0x11,       /* Key n */
};

static uint8_t m_caps_off_key_scan_str[] = /**< Key pattern to be sent when the output report has been written with the CAPS LOCK bit cleared. */
{
    0x06,       /* Key C */
    0x04,       /* Key a */
    0x13,       /* Key p */
    0x16,       /* Key s */
    0x12,       /* Key o */
    0x09,       /* Key f */
};



static void on_hids_evt(ble_hids_t * p_hids, ble_hids_evt_t * p_evt);

/**@brief Callback function for asserts in the SoftDevice.
 *
 * @details This function will be called in case of an assert in the SoftDevice.
 *
 * @warning This handler is an example only and does not fit a final product. You need to analyze
 *          how your product is supposed to react in case of Assert.
 * @warning On assert from the SoftDevice, the system can only recover on reset.
 *
 * @param[in]   line_num   Line number of the failing ASSERT call.
 * @param[in]   file_name  File name of the failing ASSERT call.
 */
void assert_nrf_callback(uint16_t line_num, const uint8_t * p_file_name)
{
    app_error_handler(DEAD_BEEF, line_num, p_file_name);
}


/**@brief Function for setting filtered whitelist.
 *
 * @param[in] skip  Filter passed to @ref pm_peer_id_list.
 */
static void whitelist_set(pm_peer_id_list_skip_t skip)
{
    pm_peer_id_t peer_ids[BLE_GAP_WHITELIST_ADDR_MAX_COUNT];
    uint32_t     peer_id_count = BLE_GAP_WHITELIST_ADDR_MAX_COUNT;

    ret_code_t err_code = pm_peer_id_list(peer_ids, &peer_id_count, PM_PEER_ID_INVALID, skip);
    APP_ERROR_CHECK(err_code);

    NRF_LOG_INFO("\tm_whitelist_peer_cnt %d, MAX_PEERS_WLIST %d",
                   peer_id_count + 1,
                   BLE_GAP_WHITELIST_ADDR_MAX_COUNT);

    err_code = pm_whitelist_set(peer_ids, peer_id_count);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for setting filtered device identities.
 *
 * @param[in] skip  Filter passed to @ref pm_peer_id_list.
 */
static void identities_set(pm_peer_id_list_skip_t skip)
{
    pm_peer_id_t peer_ids[BLE_GAP_DEVICE_IDENTITIES_MAX_COUNT];
    uint32_t     peer_id_count = BLE_GAP_DEVICE_IDENTITIES_MAX_COUNT;

    ret_code_t err_code = pm_peer_id_list(peer_ids, &peer_id_count, PM_PEER_ID_INVALID, skip);
    APP_ERROR_CHECK(err_code);

    err_code = pm_device_identities_list_set(peer_ids, peer_id_count);
    APP_ERROR_CHECK(err_code);
}


/**@brief Clear bond information from persistent storage.
 */
static void delete_bonds(void)
{
    ret_code_t err_code;

    NRF_LOG_INFO("Erase bonds!");

    err_code = pm_peers_delete();
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for starting advertising.
 */
static void advertising_start(bool erase_bonds)
{
    if (erase_bonds == true)
    {
        delete_bonds();
        // Advertising is started by PM_EVT_PEERS_DELETE_SUCCEEDED event.
    }
    else
    {
        whitelist_set(PM_PEER_ID_LIST_SKIP_NO_ID_ADDR);

        ret_code_t ret = ble_advertising_start(&m_advertising, BLE_ADV_MODE_FAST);
        APP_ERROR_CHECK(ret);
    }
}


/**@brief Function for handling Peer Manager events.
 *
 * @param[in] p_evt  Peer Manager event.
 */
static void pm_evt_handler(pm_evt_t const * p_evt)
{
    pm_handler_on_pm_evt(p_evt);
    pm_handler_flash_clean(p_evt);

    switch (p_evt->evt_id)
    {
        case PM_EVT_CONN_SEC_SUCCEEDED:
            m_peer_id = p_evt->peer_id;
            break;

        case PM_EVT_PEERS_DELETE_SUCCEEDED:
            advertising_start(false);
            break;

        case PM_EVT_PEER_DATA_UPDATE_SUCCEEDED:
            if (     p_evt->params.peer_data_update_succeeded.flash_changed
                 && (p_evt->params.peer_data_update_succeeded.data_id == PM_PEER_DATA_ID_BONDING))
            {
                NRF_LOG_INFO("New Bond, add the peer to the whitelist if possible");
                // Note: You should check on what kind of white list policy your application should use.

                whitelist_set(PM_PEER_ID_LIST_SKIP_NO_ID_ADDR);
            }
            break;

        default:
            break;
    }
}


/**@brief Function for handling Service errors.
 *
 * @details A pointer to this function will be passed to each service which may need to inform the
 *          application about an error.
 *
 * @param[in]   nrf_error   Error code containing information about what went wrong.
 */
static void service_error_handler(uint32_t nrf_error)
{
    APP_ERROR_HANDLER(nrf_error);
}


/**@brief Function for handling advertising errors.
 *
 * @param[in] nrf_error  Error code containing information about what went wrong.
 */
static void ble_advertising_error_handler(uint32_t nrf_error)
{
    APP_ERROR_HANDLER(nrf_error);
}


/**@brief Function for performing a battery measurement, and update the Battery Level characteristic in the Battery Service.
 */
static void battery_level_update(void)
{
    ret_code_t err_code;
    uint8_t  battery_level;

    battery_level = (uint8_t)sensorsim_measure(&m_battery_sim_state, &m_battery_sim_cfg);

    err_code = ble_bas_battery_level_update(&m_bas, battery_level, BLE_CONN_HANDLE_ALL);
    if ((err_code != NRF_SUCCESS) &&
        (err_code != NRF_ERROR_BUSY) &&
        (err_code != NRF_ERROR_RESOURCES) &&
        (err_code != NRF_ERROR_FORBIDDEN) &&
        (err_code != NRF_ERROR_INVALID_STATE) &&
        (err_code != BLE_ERROR_GATTS_SYS_ATTR_MISSING)
       )
    {
        APP_ERROR_HANDLER(err_code);
    }
}


/**@brief Function for handling the Battery measurement timer timeout.
 *
 * @details This function will be called each time the battery level measurement timer expires.
 *
 * @param[in]   p_context   Pointer used for passing some arbitrary information (context) from the
 *                          app_start_timer() call to the timeout handler.
 */
static void battery_level_meas_timeout_handler(void * p_context)
{
    UNUSED_PARAMETER(p_context);
    battery_level_update();
}


/**@brief Function for the Timer initialization.
 *
 * @details Initializes the timer module.
 */
static void timers_init(void)
{
    ret_code_t err_code;

    err_code = app_timer_init();
    APP_ERROR_CHECK(err_code);

    // Create battery timer.
    err_code = app_timer_create(&m_battery_timer_id,
                                APP_TIMER_MODE_REPEATED,
                                battery_level_meas_timeout_handler);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for the GAP initialization.
 *
 * @details This function sets up all the necessary GAP (Generic Access Profile) parameters of the
 *          device including the device name, appearance, and the preferred connection parameters.
 */
static void gap_params_init(void)
{
    ret_code_t              err_code;
    ble_gap_conn_params_t   gap_conn_params;
    ble_gap_conn_sec_mode_t sec_mode;

    BLE_GAP_CONN_SEC_MODE_SET_OPEN(&sec_mode);

    err_code = sd_ble_gap_device_name_set(&sec_mode,
                                          (const uint8_t *)DEVICE_NAME,
                                          strlen(DEVICE_NAME));
    APP_ERROR_CHECK(err_code);

    err_code = sd_ble_gap_appearance_set(BLE_APPEARANCE_HID_KEYBOARD);
    APP_ERROR_CHECK(err_code);

    memset(&gap_conn_params, 0, sizeof(gap_conn_params));

    gap_conn_params.min_conn_interval = MIN_CONN_INTERVAL;
    gap_conn_params.max_conn_interval = MAX_CONN_INTERVAL;
    gap_conn_params.slave_latency     = SLAVE_LATENCY;
    gap_conn_params.conn_sup_timeout  = CONN_SUP_TIMEOUT;

    err_code = sd_ble_gap_ppcp_set(&gap_conn_params);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for initializing the GATT module.
 */
static void gatt_init(void)
{
    ret_code_t err_code = nrf_ble_gatt_init(&m_gatt, NULL);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for handling Queued Write Module errors.
 *
 * @details A pointer to this function will be passed to each service which may need to inform the
 *          application about an error.
 *
 * @param[in]   nrf_error   Error code containing information about what went wrong.
 */
static void nrf_qwr_error_handler(uint32_t nrf_error)
{
    APP_ERROR_HANDLER(nrf_error);
}


/**@brief Function for initializing the Queued Write Module.
 */
static void qwr_init(void)
{
    ret_code_t         err_code;
    nrf_ble_qwr_init_t qwr_init_obj = {0};

    qwr_init_obj.error_handler = nrf_qwr_error_handler;

    err_code = nrf_ble_qwr_init(&m_qwr, &qwr_init_obj);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for initializing Device Information Service.
 */
static void dis_init(void)
{
    ret_code_t       err_code;
    ble_dis_init_t   dis_init_obj;
    ble_dis_pnp_id_t pnp_id;

    pnp_id.vendor_id_source = PNP_ID_VENDOR_ID_SOURCE;
    pnp_id.vendor_id        = PNP_ID_VENDOR_ID;
    pnp_id.product_id       = PNP_ID_PRODUCT_ID;
    pnp_id.product_version  = PNP_ID_PRODUCT_VERSION;

    memset(&dis_init_obj, 0, sizeof(dis_init_obj));

    ble_srv_ascii_to_utf8(&dis_init_obj.manufact_name_str, MANUFACTURER_NAME);
    dis_init_obj.p_pnp_id = &pnp_id;

    dis_init_obj.dis_char_rd_sec = SEC_JUST_WORKS;

    err_code = ble_dis_init(&dis_init_obj);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for initializing Battery Service.
 */
static void bas_init(void)
{
    ret_code_t     err_code;
    ble_bas_init_t bas_init_obj;

    memset(&bas_init_obj, 0, sizeof(bas_init_obj));

    bas_init_obj.evt_handler          = NULL;
    bas_init_obj.support_notification = true;
    bas_init_obj.p_report_ref         = NULL;
    bas_init_obj.initial_batt_level   = 100;

    bas_init_obj.bl_rd_sec        = SEC_JUST_WORKS;
    bas_init_obj.bl_cccd_wr_sec   = SEC_JUST_WORKS;
    bas_init_obj.bl_report_rd_sec = SEC_JUST_WORKS;

    err_code = ble_bas_init(&m_bas, &bas_init_obj);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for initializing HID Service.
 */
static void hids_init(void)
{
    ret_code_t                    err_code;
    ble_hids_init_t               hids_init_obj;
    ble_hids_inp_rep_init_t     * p_input_report;
    ble_hids_outp_rep_init_t    * p_output_report;
    ble_hids_feature_rep_init_t * p_feature_report;
    uint8_t                       hid_info_flags;

    static ble_hids_inp_rep_init_t     input_report_array[1];
    static ble_hids_outp_rep_init_t    output_report_array[1];
    static ble_hids_feature_rep_init_t feature_report_array[1];
    static uint8_t                     report_map_data[] =
    {
        0x05, 0x01,       // Usage Page (Generic Desktop)
        0x09, 0x06,       // Usage (Keyboard)
        0xA1, 0x01,       // Collection (Application)
        0x05, 0x07,       // Usage Page (Key Codes)
        0x19, 0xe0,       // Usage Minimum (224)
        0x29, 0xe7,       // Usage Maximum (231)
        0x15, 0x00,       // Logical Minimum (0)
        0x25, 0x01,       // Logical Maximum (1)
        0x75, 0x01,       // Report Size (1)
        0x95, 0x08,       // Report Count (8)
        0x81, 0x02,       // Input (Data, Variable, Absolute)

        0x95, 0x01,       // Report Count (1)
        0x75, 0x08,       // Report Size (8)
        0x81, 0x01,       // Input (Constant) reserved byte(1)

        0x95, 0x05,       // Report Count (5)
        0x75, 0x01,       // Report Size (1)
        0x05, 0x08,       // Usage Page (Page# for LEDs)
        0x19, 0x01,       // Usage Minimum (1)
        0x29, 0x05,       // Usage Maximum (5)
        0x91, 0x02,       // Output (Data, Variable, Absolute), Led report
        0x95, 0x01,       // Report Count (1)
        0x75, 0x03,       // Report Size (3)
        0x91, 0x01,       // Output (Data, Variable, Absolute), Led report padding

        0x95, 0x06,       // Report Count (6)
        0x75, 0x08,       // Report Size (8)
        0x15, 0x00,       // Logical Minimum (0)
        0x25, 0x65,       // Logical Maximum (101)
        0x05, 0x07,       // Usage Page (Key codes)
        0x19, 0x00,       // Usage Minimum (0)
        0x29, 0x65,       // Usage Maximum (101)
        0x81, 0x00,       // Input (Data, Array) Key array(6 bytes)

        0x09, 0x05,       // Usage (Vendor Defined)
        0x15, 0x00,       // Logical Minimum (0)
        0x26, 0xFF, 0x00, // Logical Maximum (255)
        0x75, 0x08,       // Report Size (8 bit)
        0x95, 0x02,       // Report Count (2) // have we need to change?
        0xB1, 0x02,       // Feature (Data, Variable, Absolute)

        0xC0              // End Collection (Application)
    };

    memset((void *)input_report_array, 0, sizeof(ble_hids_inp_rep_init_t));
    memset((void *)output_report_array, 0, sizeof(ble_hids_outp_rep_init_t));
    memset((void *)feature_report_array, 0, sizeof(ble_hids_feature_rep_init_t));

    // Initialize HID Service
    p_input_report                      = &input_report_array[INPUT_REPORT_KEYS_INDEX];
    p_input_report->max_len             = INPUT_REPORT_KEYS_MAX_LEN;
    p_input_report->rep_ref.report_id   = INPUT_REP_REF_ID;
    p_input_report->rep_ref.report_type = BLE_HIDS_REP_TYPE_INPUT;

    p_input_report->sec.cccd_wr = SEC_JUST_WORKS;
    p_input_report->sec.wr      = SEC_JUST_WORKS;
    p_input_report->sec.rd      = SEC_JUST_WORKS;

    p_output_report                      = &output_report_array[OUTPUT_REPORT_INDEX];
    p_output_report->max_len             = OUTPUT_REPORT_MAX_LEN;
    p_output_report->rep_ref.report_id   = OUTPUT_REP_REF_ID;
    p_output_report->rep_ref.report_type = BLE_HIDS_REP_TYPE_OUTPUT;

    p_output_report->sec.wr = SEC_JUST_WORKS;
    p_output_report->sec.rd = SEC_JUST_WORKS;

    p_feature_report                      = &feature_report_array[FEATURE_REPORT_INDEX];
    p_feature_report->max_len             = FEATURE_REPORT_MAX_LEN;
    p_feature_report->rep_ref.report_id   = FEATURE_REP_REF_ID;
    p_feature_report->rep_ref.report_type = BLE_HIDS_REP_TYPE_FEATURE;

    p_feature_report->sec.rd              = SEC_JUST_WORKS;
    p_feature_report->sec.wr              = SEC_JUST_WORKS;

    hid_info_flags = HID_INFO_FLAG_REMOTE_WAKE_MSK | HID_INFO_FLAG_NORMALLY_CONNECTABLE_MSK;

    memset(&hids_init_obj, 0, sizeof(hids_init_obj));

    hids_init_obj.evt_handler                    = on_hids_evt;
    hids_init_obj.error_handler                  = service_error_handler;
    hids_init_obj.is_kb                          = true;
    hids_init_obj.is_mouse                       = false;
    hids_init_obj.inp_rep_count                  = 1;
    hids_init_obj.p_inp_rep_array                = input_report_array;
    hids_init_obj.outp_rep_count                 = 1;
    hids_init_obj.p_outp_rep_array               = output_report_array;
    hids_init_obj.feature_rep_count              = 1;
    hids_init_obj.p_feature_rep_array            = feature_report_array;
    hids_init_obj.rep_map.data_len               = sizeof(report_map_data);
    hids_init_obj.rep_map.p_data                 = report_map_data;
    hids_init_obj.hid_information.bcd_hid        = BASE_USB_HID_SPEC_VERSION;
    hids_init_obj.hid_information.b_country_code = 0;
    hids_init_obj.hid_information.flags          = hid_info_flags;
    hids_init_obj.included_services_count        = 0;
    hids_init_obj.p_included_services_array      = NULL;

    hids_init_obj.rep_map.rd_sec         = SEC_JUST_WORKS;
    hids_init_obj.hid_information.rd_sec = SEC_JUST_WORKS;

    hids_init_obj.boot_kb_inp_rep_sec.cccd_wr = SEC_JUST_WORKS;
    hids_init_obj.boot_kb_inp_rep_sec.rd      = SEC_JUST_WORKS;

    hids_init_obj.boot_kb_outp_rep_sec.rd = SEC_JUST_WORKS;
    hids_init_obj.boot_kb_outp_rep_sec.wr = SEC_JUST_WORKS;

    hids_init_obj.protocol_mode_rd_sec = SEC_JUST_WORKS;
    hids_init_obj.protocol_mode_wr_sec = SEC_JUST_WORKS;
    hids_init_obj.ctrl_point_wr_sec    = SEC_JUST_WORKS;

    err_code = ble_hids_init(&m_hids, &hids_init_obj);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for initializing services that will be used by the application.
 */
static void services_init(void)
{
    qwr_init();
    dis_init();
    bas_init();
    hids_init();
}


/**@brief Function for initializing the battery sensor simulator.
 */
static void sensor_simulator_init(void)
{
    m_battery_sim_cfg.min          = MIN_BATTERY_LEVEL;
    m_battery_sim_cfg.max          = MAX_BATTERY_LEVEL;
    m_battery_sim_cfg.incr         = BATTERY_LEVEL_INCREMENT;
    m_battery_sim_cfg.start_at_max = true;

    sensorsim_init(&m_battery_sim_state, &m_battery_sim_cfg);
}


/**@brief Function for handling a Connection Parameters error.
 *
 * @param[in]   nrf_error   Error code containing information about what went wrong.
 */
static void conn_params_error_handler(uint32_t nrf_error)
{
    APP_ERROR_HANDLER(nrf_error);
}


/**@brief Function for initializing the Connection Parameters module.
 */
static void conn_params_init(void)
{
    ret_code_t             err_code;
    ble_conn_params_init_t cp_init;

    memset(&cp_init, 0, sizeof(cp_init));

    cp_init.p_conn_params                  = NULL;
    cp_init.first_conn_params_update_delay = FIRST_CONN_PARAMS_UPDATE_DELAY;
    cp_init.next_conn_params_update_delay  = NEXT_CONN_PARAMS_UPDATE_DELAY;
    cp_init.max_conn_params_update_count   = MAX_CONN_PARAMS_UPDATE_COUNT;
    cp_init.start_on_notify_cccd_handle    = BLE_GATT_HANDLE_INVALID;
    cp_init.disconnect_on_fail             = false;
    cp_init.evt_handler                    = NULL;
    cp_init.error_handler                  = conn_params_error_handler;

    err_code = ble_conn_params_init(&cp_init);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for starting timers.
 */
static void timers_start(void)
{
    ret_code_t err_code;

    err_code = app_timer_start(m_battery_timer_id, BATTERY_LEVEL_MEAS_INTERVAL, NULL);
    APP_ERROR_CHECK(err_code);
}


/**@brief   Function for transmitting a key scan Press & Release Notification.
 *
 * @warning This handler is an example only. You need to analyze how you wish to send the key
 *          release.
 *
 * @param[in]  p_instance     Identifies the service for which Key Notifications are requested.
 * @param[in]  p_key_pattern  Pointer to key pattern.
 * @param[in]  pattern_len    Length of key pattern. 0 < pattern_len < 7.
 * @param[in]  pattern_offset Offset applied to Key Pattern for transmission.
 * @param[out] actual_len     Provides actual length of Key Pattern transmitted, making buffering of
 *                            rest possible if needed.
 * @return     NRF_SUCCESS on success, NRF_ERROR_RESOURCES in case transmission could not be
 *             completed due to lack of transmission buffer or other error codes indicating reason
 *             for failure.
 *
 * @note       In case of NRF_ERROR_RESOURCES, remaining pattern that could not be transmitted
 *             can be enqueued \ref buffer_enqueue function.
 *             In case a pattern of 'cofFEe' is the p_key_pattern, with pattern_len as 6 and
 *             pattern_offset as 0, the notifications as observed on the peer side would be
 *             1>    'c', 'o', 'f', 'F', 'E', 'e'
 *             2>    -  , 'o', 'f', 'F', 'E', 'e'
 *             3>    -  ,   -, 'f', 'F', 'E', 'e'
 *             4>    -  ,   -,   -, 'F', 'E', 'e'
 *             5>    -  ,   -,   -,   -, 'E', 'e'
 *             6>    -  ,   -,   -,   -,   -, 'e'
 *             7>    -  ,   -,   -,   -,   -,  -
 *             Here, '-' refers to release, 'c' refers to the key character being transmitted.
 *             Therefore 7 notifications will be sent.
 *             In case an offset of 4 was provided, the pattern notifications sent will be from 5-7
 *             will be transmitted.
 */
static uint32_t send_key_scan_press_release(ble_hids_t * p_hids,
                                            uint8_t    * p_key_pattern,
                                            uint16_t     pattern_len,
                                            uint16_t     pattern_offset,
                                            uint16_t   * p_actual_len)
{
    ret_code_t err_code;
    uint16_t offset;
    uint16_t data_len;
    uint8_t  data[INPUT_REPORT_KEYS_MAX_LEN];

    // HID Report Descriptor enumerates an array of size 6, the pattern hence shall not be any
    // longer than this.
    STATIC_ASSERT((INPUT_REPORT_KEYS_MAX_LEN - 2) == 6);

    ASSERT(pattern_len <= (INPUT_REPORT_KEYS_MAX_LEN - 2));

    offset   = pattern_offset;
    data_len = pattern_len;

    do
    {
        // Reset the data buffer.
        memset(data, 0, sizeof(data));

        // Copy the scan code.
        memcpy(data + SCAN_CODE_POS + offset, p_key_pattern + offset, data_len - offset);

        if (bsp_button_is_pressed(SHIFT_BUTTON_ID))
        {
            data[MODIFIER_KEY_POS] |= SHIFT_KEY_CODE;
        }

        if (!m_in_boot_mode)
        {
            err_code = ble_hids_inp_rep_send(p_hids,
                                             INPUT_REPORT_KEYS_INDEX,
                                             INPUT_REPORT_KEYS_MAX_LEN,
                                             data,
                                             m_conn_handle);
        }
        else
        {
            err_code = ble_hids_boot_kb_inp_rep_send(p_hids,
                                                     INPUT_REPORT_KEYS_MAX_LEN,
                                                     data,
                                                     m_conn_handle);
        }

        if (err_code != NRF_SUCCESS)
        {
            break;
        }

        offset++;
    }
    while (offset <= data_len);

    *p_actual_len = offset;

    return err_code;
}


/**@brief   Function for initializing the buffer queue used to key events that could not be
 *          transmitted
 *
 * @warning This handler is an example only. You need to analyze how you wish to buffer or buffer at
 *          all.
 *
 * @note    In case of HID keyboard, a temporary buffering could be employed to handle scenarios
 *          where encryption is not yet enabled or there was a momentary link loss or there were no
 *          Transmit buffers.
 */
static void buffer_init(void)
{
    uint32_t buffer_count;

    BUFFER_LIST_INIT();

    for (buffer_count = 0; buffer_count < MAX_BUFFER_ENTRIES; buffer_count++)
    {
        BUFFER_ELEMENT_INIT(buffer_count);
    }
}


/**@brief Function for enqueuing key scan patterns that could not be transmitted either completely
 *        or partially.
 *
 * @warning This handler is an example only. You need to analyze how you wish to send the key
 *          release.
 *
 * @param[in]  p_hids         Identifies the service for which Key Notifications are buffered.
 * @param[in]  p_key_pattern  Pointer to key pattern.
 * @param[in]  pattern_len    Length of key pattern.
 * @param[in]  offset         Offset applied to Key Pattern when requesting a transmission on
 *                            dequeue, @ref buffer_dequeue.
 * @return     NRF_SUCCESS on success, else an error code indicating reason for failure.
 */
static uint32_t buffer_enqueue(ble_hids_t * p_hids,
                               uint8_t    * p_key_pattern,
                               uint16_t     pattern_len,
                               uint16_t     offset)
{
    buffer_entry_t * element;
    uint32_t         err_code = NRF_SUCCESS;

    if (BUFFER_LIST_FULL())
    {
        // Element cannot be buffered.
        err_code = NRF_ERROR_NO_MEM;
    }
    else
    {
        // Make entry of buffer element and copy data.
        element              = &buffer_list.buffer[(buffer_list.wp)];
        element->p_instance  = p_hids;
        element->p_data      = p_key_pattern;
        element->data_offset = offset;
        element->data_len    = pattern_len;

        buffer_list.count++;
        buffer_list.wp++;

        if (buffer_list.wp == MAX_BUFFER_ENTRIES)
        {
            buffer_list.wp = 0;
        }
    }

    return err_code;
}


/**@brief   Function to dequeue key scan patterns that could not be transmitted either completely of
 *          partially.
 *
 * @warning This handler is an example only. You need to analyze how you wish to send the key
 *          release.
 *
 * @param[in]  tx_flag   Indicative of whether the dequeue should result in transmission or not.
 * @note       A typical example when all keys are dequeued with transmission is when link is
 *             disconnected.
 *
 * @return     NRF_SUCCESS on success, else an error code indicating reason for failure.
 */
static uint32_t buffer_dequeue(bool tx_flag)
{
    buffer_entry_t * p_element;
    uint32_t         err_code = NRF_SUCCESS;
    uint16_t         actual_len;

    if (BUFFER_LIST_EMPTY())
    {
        err_code = NRF_ERROR_NOT_FOUND;
    }
    else
    {
        bool remove_element = true;

        p_element = &buffer_list.buffer[(buffer_list.rp)];

        if (tx_flag)
        {
            err_code = send_key_scan_press_release(p_element->p_instance,
                                                   p_element->p_data,
                                                   p_element->data_len,
                                                   p_element->data_offset,
                                                   &actual_len);
            // An additional notification is needed for release of all keys, therefore check
            // is for actual_len <= element->data_len and not actual_len < element->data_len
            if ((err_code == NRF_ERROR_RESOURCES) && (actual_len <= p_element->data_len))
            {
                // Transmission could not be completed, do not remove the entry, adjust next data to
                // be transmitted
                p_element->data_offset = actual_len;
                remove_element         = false;
            }
        }

        if (remove_element)
        {
            BUFFER_ELEMENT_INIT(buffer_list.rp);

            buffer_list.rp++;
            buffer_list.count--;

            if (buffer_list.rp == MAX_BUFFER_ENTRIES)
            {
                buffer_list.rp = 0;
            }
        }
    }

    return err_code;
}


/**@brief Function for sending sample key presses to the peer.
 *
 * @param[in]   key_pattern_len   Pattern length.
 * @param[in]   p_key_pattern     Pattern to be sent.
 */
static void keys_send(uint8_t key_pattern_len, uint8_t * p_key_pattern)
{
    ret_code_t err_code;
    uint16_t actual_len;

    err_code = send_key_scan_press_release(&m_hids,
                                           p_key_pattern,
                                           key_pattern_len,
                                           0,
                                           &actual_len);
    // An additional notification is needed for release of all keys, therefore check
    // is for actual_len <= key_pattern_len and not actual_len < key_pattern_len.
    if ((err_code == NRF_ERROR_RESOURCES) && (actual_len <= key_pattern_len))
    {
        // Buffer enqueue routine return value is not intentionally checked.
        // Rationale: Its better to have a a few keys missing than have a system
        // reset. Recommendation is to work out most optimal value for
        // MAX_BUFFER_ENTRIES to minimize chances of buffer queue full condition
        UNUSED_VARIABLE(buffer_enqueue(&m_hids, p_key_pattern, key_pattern_len, actual_len));
    }


    if ((err_code != NRF_SUCCESS) &&
        (err_code != NRF_ERROR_INVALID_STATE) &&
        (err_code != NRF_ERROR_RESOURCES) &&
        (err_code != NRF_ERROR_BUSY) &&
        (err_code != BLE_ERROR_GATTS_SYS_ATTR_MISSING)
       )
    {
        APP_ERROR_HANDLER(err_code);
    }
}


/**@brief Function for handling the HID Report Characteristic Write event.
 *
 * @param[in]   p_evt   HID service event.
 */
static void on_hid_rep_char_write(ble_hids_evt_t * p_evt)
{
    NRF_LOG_INFO("HID endpointOUT type: %d, index %d",p_evt->params.char_write.char_id.rep_type,p_evt->params.char_write.char_id.rep_index);
    NRF_LOG_INFO("dump data:");
    NRF_LOG_HEXDUMP_INFO(p_evt->params.char_write.data, p_evt->params.char_write.len);
    //hid_callbak_application_specific(p_evt->params.char_write.data)

    if (p_evt->params.char_write.char_id.rep_type == BLE_HIDS_REP_TYPE_OUTPUT)
    {
        ret_code_t err_code;
        uint8_t  report_val[64];
        uint8_t  report_index = p_evt->params.char_write.char_id.rep_index;

        if (report_index == OUTPUT_REPORT_INDEX)
        {
            // This code assumes that the output report is one byte long. Hence the following
            // static assert is made.
            //STATIC_ASSERT(OUTPUT_REPORT_MAX_LEN == 20); // was == 1)

            err_code = ble_hids_outp_rep_get(&m_hids,
                                             report_index,
                                             OUTPUT_REPORT_MAX_LEN,
                                             0,
                                             m_conn_handle,
                                             report_val);
            APP_ERROR_CHECK(err_code);

            if (!m_caps_on && ((report_val[0] & OUTPUT_REPORT_BIT_MASK_CAPS_LOCK) != 0))
            {
                // Caps Lock is turned On.
                NRF_LOG_INFO("Caps Lock is turned On!");
                err_code = bsp_indication_set(BSP_INDICATE_ALERT_3);
                APP_ERROR_CHECK(err_code);

                keys_send(sizeof(m_caps_on_key_scan_str), m_caps_on_key_scan_str);
                m_caps_on = true;
            }
            else if (m_caps_on && ((report_val[0] & OUTPUT_REPORT_BIT_MASK_CAPS_LOCK) == 0))
            {
                // Caps Lock is turned Off .
                NRF_LOG_INFO("Caps Lock is turned Off!");
                err_code = bsp_indication_set(BSP_INDICATE_ALERT_OFF);
                APP_ERROR_CHECK(err_code);

                keys_send(sizeof(m_caps_off_key_scan_str), m_caps_off_key_scan_str);
                m_caps_on = false;
            }
            else
            {
                // The report received is not supported by this application. Do nothing.
            }
        }
    }
}


/**@brief Function for putting the chip into sleep mode.
 *
 * @note This function will not return.
 */
static void sleep_mode_enter(void)
{
    ret_code_t err_code;

    err_code = bsp_indication_set(BSP_INDICATE_IDLE);
    APP_ERROR_CHECK(err_code);

    // Prepare wakeup buttons.
    err_code = bsp_btn_ble_sleep_mode_prepare();
    APP_ERROR_CHECK(err_code);

    // Go to system-off mode (this function will not return; wakeup will cause a reset).
    err_code = sd_power_system_off();
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for handling HID events.
 *
 * @details This function will be called for all HID events which are passed to the application.
 *
 * @param[in]   p_hids  HID service structure.
 * @param[in]   p_evt   Event received from the HID service.
 */
static void on_hids_evt(ble_hids_t * p_hids, ble_hids_evt_t * p_evt)
{
    switch (p_evt->evt_type)
    {
        case BLE_HIDS_EVT_BOOT_MODE_ENTERED:
            m_in_boot_mode = true;
            break;

        case BLE_HIDS_EVT_REPORT_MODE_ENTERED:
            m_in_boot_mode = false;
            break;

        case BLE_HIDS_EVT_REP_CHAR_WRITE:
            on_hid_rep_char_write(p_evt);
            break;

        case BLE_HIDS_EVT_NOTIF_ENABLED:
            break;

        default:
            // No implementation needed.
            break;
    }
}


/**@brief Function for handling advertising events.
 *
 * @details This function will be called for advertising events which are passed to the application.
 *
 * @param[in] ble_adv_evt  Advertising event.
 */
static void on_adv_evt(ble_adv_evt_t ble_adv_evt)
{
    ret_code_t err_code;

    switch (ble_adv_evt)
    {
        case BLE_ADV_EVT_DIRECTED_HIGH_DUTY:
            NRF_LOG_INFO("High Duty Directed advertising.");
            err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING_DIRECTED);
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_ADV_EVT_DIRECTED:
            NRF_LOG_INFO("Directed advertising.");
            err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING_DIRECTED);
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_ADV_EVT_FAST:
            NRF_LOG_INFO("Fast advertising.");
            err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING);
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_ADV_EVT_SLOW:
            NRF_LOG_INFO("Slow advertising.");
            err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING_SLOW);
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_ADV_EVT_FAST_WHITELIST:
            NRF_LOG_INFO("Fast advertising with whitelist.");
            err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING_WHITELIST);
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_ADV_EVT_SLOW_WHITELIST:
            NRF_LOG_INFO("Slow advertising with whitelist.");
            err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING_WHITELIST);
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_ADV_EVT_IDLE:
            sleep_mode_enter();
            break;

        case BLE_ADV_EVT_WHITELIST_REQUEST:
        {
            ble_gap_addr_t whitelist_addrs[BLE_GAP_WHITELIST_ADDR_MAX_COUNT];
            ble_gap_irk_t  whitelist_irks[BLE_GAP_WHITELIST_ADDR_MAX_COUNT];
            uint32_t       addr_cnt = BLE_GAP_WHITELIST_ADDR_MAX_COUNT;
            uint32_t       irk_cnt  = BLE_GAP_WHITELIST_ADDR_MAX_COUNT;

            err_code = pm_whitelist_get(whitelist_addrs, &addr_cnt,
                                        whitelist_irks,  &irk_cnt);
            APP_ERROR_CHECK(err_code);
            NRF_LOG_DEBUG("pm_whitelist_get returns %d addr in whitelist and %d irk whitelist",
                          addr_cnt, irk_cnt);

            // Set the correct identities list (no excluding peers with no Central Address Resolution).
            identities_set(PM_PEER_ID_LIST_SKIP_NO_IRK);

            // Apply the whitelist.
            err_code = ble_advertising_whitelist_reply(&m_advertising,
                                                       whitelist_addrs,
                                                       addr_cnt,
                                                       whitelist_irks,
                                                       irk_cnt);
            APP_ERROR_CHECK(err_code);
        } break; //BLE_ADV_EVT_WHITELIST_REQUEST

        case BLE_ADV_EVT_PEER_ADDR_REQUEST:
        {
            pm_peer_data_bonding_t peer_bonding_data;

            // Only Give peer address if we have a handle to the bonded peer.
            if (m_peer_id != PM_PEER_ID_INVALID)
            {
                err_code = pm_peer_data_bonding_load(m_peer_id, &peer_bonding_data);
                if (err_code != NRF_ERROR_NOT_FOUND)
                {
                    APP_ERROR_CHECK(err_code);

                    // Manipulate identities to exclude peers with no Central Address Resolution.
                    identities_set(PM_PEER_ID_LIST_SKIP_ALL);

                    ble_gap_addr_t * p_peer_addr = &(peer_bonding_data.peer_ble_id.id_addr_info);
                    err_code = ble_advertising_peer_addr_reply(&m_advertising, p_peer_addr);
                    APP_ERROR_CHECK(err_code);
                }
            }
        } break; //BLE_ADV_EVT_PEER_ADDR_REQUEST

        default:
            break;
    }
}


/**@brief Function for handling BLE events.
 *
 * @param[in]   p_ble_evt   Bluetooth stack event.
 * @param[in]   p_context   Unused.
 */
static void ble_evt_handler(ble_evt_t const * p_ble_evt, void * p_context)
{
    ret_code_t err_code;

    switch (p_ble_evt->header.evt_id)
    {
        case BLE_GAP_EVT_CONNECTED:
            NRF_LOG_INFO("Connected");
            err_code = bsp_indication_set(BSP_INDICATE_CONNECTED);
            APP_ERROR_CHECK(err_code);
            m_conn_handle = p_ble_evt->evt.gap_evt.conn_handle;
            err_code = nrf_ble_qwr_conn_handle_assign(&m_qwr, m_conn_handle);
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_GAP_EVT_DISCONNECTED:
            NRF_LOG_INFO("Disconnected");
            // Dequeue all keys without transmission.
            (void) buffer_dequeue(false);

            m_conn_handle = BLE_CONN_HANDLE_INVALID;

            // Reset m_caps_on variable. Upon reconnect, the HID host will re-send the Output
            // report containing the Caps lock state.
            m_caps_on = false;
            // disabling alert 3. signal - used for capslock ON
            err_code = bsp_indication_set(BSP_INDICATE_ALERT_OFF);
            APP_ERROR_CHECK(err_code);

            break; // BLE_GAP_EVT_DISCONNECTED

        case BLE_GAP_EVT_PHY_UPDATE_REQUEST:
        {
            NRF_LOG_DEBUG("PHY update request.");
            ble_gap_phys_t const phys =
            {
                .rx_phys = BLE_GAP_PHY_AUTO,
                .tx_phys = BLE_GAP_PHY_AUTO,
            };
            err_code = sd_ble_gap_phy_update(p_ble_evt->evt.gap_evt.conn_handle, &phys);
            APP_ERROR_CHECK(err_code);
        } break;

        case BLE_GATTS_EVT_HVN_TX_COMPLETE:
            // Send next key event
            (void) buffer_dequeue(true);
            break;

        case BLE_GATTC_EVT_TIMEOUT:
            // Disconnect on GATT Client timeout event.
            NRF_LOG_DEBUG("GATT Client Timeout.");
            err_code = sd_ble_gap_disconnect(p_ble_evt->evt.gattc_evt.conn_handle,
                                             BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_GATTS_EVT_TIMEOUT:
            // Disconnect on GATT Server timeout event.
            NRF_LOG_DEBUG("GATT Server Timeout.");
            err_code = sd_ble_gap_disconnect(p_ble_evt->evt.gatts_evt.conn_handle,
                                             BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
            APP_ERROR_CHECK(err_code);
            break;

        default:
            // No implementation needed.
            break;
    }
}


/**@brief Function for initializing the BLE stack.
 *
 * @details Initializes the SoftDevice and the BLE event interrupt.
 */
static void ble_stack_init(void)
{
    ret_code_t err_code;

    err_code = nrf_sdh_enable_request();
    APP_ERROR_CHECK(err_code);

    // Configure the BLE stack using the default settings.
    // Fetch the start address of the application RAM.
    uint32_t ram_start = 0;
    err_code = nrf_sdh_ble_default_cfg_set(APP_BLE_CONN_CFG_TAG, &ram_start);
    APP_ERROR_CHECK(err_code);

    // Enable BLE stack.
    err_code = nrf_sdh_ble_enable(&ram_start);
    APP_ERROR_CHECK(err_code);

    // Register a handler for BLE events.
    NRF_SDH_BLE_OBSERVER(m_ble_observer, APP_BLE_OBSERVER_PRIO, ble_evt_handler, NULL);
}


/**@brief Function for the Event Scheduler initialization.
 */
static void scheduler_init(void)
{
    APP_SCHED_INIT(SCHED_MAX_EVENT_DATA_SIZE, SCHED_QUEUE_SIZE);
}


/**@brief Function for handling events from the BSP module.
 *
 * @param[in]   event   Event generated by button press.
 */
static void bsp_event_handler(bsp_event_t event)
{
    uint32_t         err_code;
    static uint8_t * p_key = m_sample_key_press_scan_str;
    static uint8_t   size  = 0;

    switch (event)
    {
        case BSP_EVENT_SLEEP:
            sleep_mode_enter();
            break;

        case BSP_EVENT_DISCONNECT:
            err_code = sd_ble_gap_disconnect(m_conn_handle,
                                             BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
            if (err_code != NRF_ERROR_INVALID_STATE)
            {
                APP_ERROR_CHECK(err_code);
            }
            break;

        case BSP_EVENT_WHITELIST_OFF:
            if (m_conn_handle == BLE_CONN_HANDLE_INVALID)
            {
                err_code = ble_advertising_restart_without_whitelist(&m_advertising);
                if (err_code != NRF_ERROR_INVALID_STATE)
                {
                    APP_ERROR_CHECK(err_code);
                }
            }
            break;

        case BSP_EVENT_KEY_0:
            if (m_conn_handle != BLE_CONN_HANDLE_INVALID)
            {
                keys_send(1, p_key);
                p_key++;
                size++;
                if (size == MAX_KEYS_IN_ONE_REPORT)
                {
                    p_key = m_sample_key_press_scan_str;
                    size  = 0;
                }
            }
            break;

        default:
            break;
    }
}


/**@brief Function for the Peer Manager initialization.
 */
static void peer_manager_init(void)
{
    ble_gap_sec_params_t sec_param;
    ret_code_t           err_code;

    err_code = pm_init();
    APP_ERROR_CHECK(err_code);

    memset(&sec_param, 0, sizeof(ble_gap_sec_params_t));

    // Security parameters to be used for all security procedures.
    sec_param.bond           = SEC_PARAM_BOND;
    sec_param.mitm           = SEC_PARAM_MITM;
    sec_param.lesc           = SEC_PARAM_LESC;
    sec_param.keypress       = SEC_PARAM_KEYPRESS;
    sec_param.io_caps        = SEC_PARAM_IO_CAPABILITIES;
    sec_param.oob            = SEC_PARAM_OOB;
    sec_param.min_key_size   = SEC_PARAM_MIN_KEY_SIZE;
    sec_param.max_key_size   = SEC_PARAM_MAX_KEY_SIZE;
    sec_param.kdist_own.enc  = 1;
    sec_param.kdist_own.id   = 1;
    sec_param.kdist_peer.enc = 1;
    sec_param.kdist_peer.id  = 1;

	// to un-comment! In this way there will not any security parameters!
    err_code = pm_sec_params_set(&sec_param);
    APP_ERROR_CHECK(err_code);

    err_code = pm_register(pm_evt_handler);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for initializing the Advertising functionality.
 */
static void advertising_init(void)
{
    uint32_t               err_code;
    uint8_t                adv_flags;
    ble_advertising_init_t init;

    memset(&init, 0, sizeof(init));

    adv_flags                            = BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE;
    init.advdata.name_type               = BLE_ADVDATA_FULL_NAME;
    init.advdata.include_appearance      = true;
    init.advdata.flags                   = adv_flags;
    init.advdata.uuids_complete.uuid_cnt = sizeof(m_adv_uuids) / sizeof(m_adv_uuids[0]);
    init.advdata.uuids_complete.p_uuids  = m_adv_uuids;

    init.config.ble_adv_whitelist_enabled          = true;
    init.config.ble_adv_directed_high_duty_enabled = true;
    init.config.ble_adv_directed_enabled           = false;
    init.config.ble_adv_directed_interval          = 0;
    init.config.ble_adv_directed_timeout           = 0;
    init.config.ble_adv_fast_enabled               = true;
    init.config.ble_adv_fast_interval              = APP_ADV_FAST_INTERVAL;
    init.config.ble_adv_fast_timeout               = 0x00; // to keep infinite advertising //was APP_ADV_FAST_DURATION;
    init.config.ble_adv_slow_enabled               = true;
    init.config.ble_adv_slow_interval              = APP_ADV_SLOW_INTERVAL;
    init.config.ble_adv_slow_timeout               = APP_ADV_SLOW_DURATION;

    init.evt_handler   = on_adv_evt;
    init.error_handler = ble_advertising_error_handler;

    err_code = ble_advertising_init(&m_advertising, &init);
    APP_ERROR_CHECK(err_code);

    ble_advertising_conn_cfg_tag_set(&m_advertising, APP_BLE_CONN_CFG_TAG);
}


/**@brief Function for initializing buttons and leds.
 *
 * @param[out] p_erase_bonds  Will be true if the clear bonding button was pressed to wake the application up.
 */
static void buttons_leds_init(bool * p_erase_bonds)
{
    ret_code_t err_code;
    bsp_event_t startup_event;

    err_code = bsp_init(BSP_INIT_LEDS | BSP_INIT_BUTTONS, bsp_event_handler);
    APP_ERROR_CHECK(err_code);

    err_code = bsp_btn_ble_init(NULL, &startup_event);
    APP_ERROR_CHECK(err_code);

    *p_erase_bonds = (startup_event == BSP_EVENT_CLEAR_BONDING_DATA);
}


/**@brief Function for initializing the nrf log module.
 */
static void log_init(void)
{
    ret_code_t err_code = NRF_LOG_INIT(NULL);
    APP_ERROR_CHECK(err_code);

    NRF_LOG_DEFAULT_BACKENDS_INIT();
}


/**@brief Function for initializing power management.
 */
static void power_management_init(void)
{
    ret_code_t err_code;
    err_code = nrf_pwr_mgmt_init();
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for handling the idle state (main loop).
 *
 * @details If there is no pending log operation, then sleep until next the next event occurs.
 */
static void idle_state_handle(void)
{
    app_sched_execute();
    if (NRF_LOG_PROCESS() == false)
    {
        nrf_pwr_mgmt_run();
    }
}


/**@brief Function for application main entry.
 */
int main(void)
{
    bool erase_bonds;

    // Initialize.
    log_init();
    timers_init();
    buttons_leds_init(&erase_bonds);
    power_management_init();
    ble_stack_init();
    scheduler_init();
    gap_params_init();
    gatt_init();
    advertising_init();
    services_init();
    sensor_simulator_init();
    conn_params_init();
    buffer_init();
    peer_manager_init();

    // Start execution.
    NRF_LOG_INFO("HID Keyboard example started.");
    timers_start();
    advertising_start(erase_bonds);

    // Enter main loop.
    for (;;)
    {
        idle_state_handle();
    }
}


/**
 * @}
 */

[ovrebekk]

Hi Alberto

Sorry for the slow response. I just got back from several weeks of leave and will need some more time to try and test this on my end. 

Have there been any developments on your end in the mean time?

Best regards
Torbjørn