I am currently evaluating the nrf52840 for a possible future application which is based around BLE and should also provide a HID Generic interface to perform communication with a computer. Nothing special, just some random data every few seconds.
The BLE part is working so far but I am struggling with the USB HID part. I browsed the available examples and found some under the peripheral branch and some in the ble_peripheral branch (nRF5 16.0.0 SDK). The issue lies with the setup of the usb descriptors for HID. I found that many examples (e.g. ble_app_hids_mouse_pca10056_s140) rely on e.g. the following 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;
uint8_t hid_info_flags;
static ble_hids_inp_rep_init_t inp_rep_array[INPUT_REPORT_COUNT];
static uint8_t rep_map_data[] =
{
0x05, 0x01, // Usage Page (Generic Desktop)
0x09, 0x02, // Usage (Mouse)
0xA1, 0x01, // Collection (Application)
// Report ID 1: Mouse buttons + scroll/pan
0x85, 0x01, // Report Id 1
0x09, 0x01, // Usage (Pointer)
0xA1, 0x00, // Collection (Physical)
0x95, 0x05, // Report Count (3)
0x75, 0x01, // Report Size (1)
0x05, 0x09, // Usage Page (Buttons)
0x19, 0x01, // Usage Minimum (01)
0x29, 0x05, // Usage Maximum (05)
0x15, 0x00, // Logical Minimum (0)
0x25, 0x01, // Logical Maximum (1)
0x81, 0x02, // Input (Data, Variable, Absolute)
0x95, 0x01, // Report Count (1)
0x75, 0x03, // Report Size (3)
0x81, 0x01, // Input (Constant) for padding
0x75, 0x08, // Report Size (8)
0x95, 0x01, // Report Count (1)
0x05, 0x01, // Usage Page (Generic Desktop)
0x09, 0x38, // Usage (Wheel)
0x15, 0x81, // Logical Minimum (-127)
0x25, 0x7F, // Logical Maximum (127)
0x81, 0x06, // Input (Data, Variable, Relative)
0x05, 0x0C, // Usage Page (Consumer)
0x0A, 0x38, 0x02, // Usage (AC Pan)
0x95, 0x01, // Report Count (1)
0x81, 0x06, // Input (Data,Value,Relative,Bit Field)
0xC0, // End Collection (Physical)
// Report ID 2: Mouse motion
0x85, 0x02, // Report Id 2
0x09, 0x01, // Usage (Pointer)
0xA1, 0x00, // Collection (Physical)
0x75, 0x0C, // Report Size (12)
0x95, 0x02, // Report Count (2)
0x05, 0x01, // Usage Page (Generic Desktop)
0x09, 0x30, // Usage (X)
0x09, 0x31, // Usage (Y)
0x16, 0x01, 0xF8, // Logical maximum (2047)
0x26, 0xFF, 0x07, // Logical minimum (-2047)
0x81, 0x06, // Input (Data, Variable, Relative)
0xC0, // End Collection (Physical)
0xC0, // End Collection (Application)
// Report ID 3: Advanced buttons
0x05, 0x0C, // Usage Page (Consumer)
0x09, 0x01, // Usage (Consumer Control)
0xA1, 0x01, // Collection (Application)
0x85, 0x03, // Report Id (3)
0x15, 0x00, // Logical minimum (0)
0x25, 0x01, // Logical maximum (1)
0x75, 0x01, // Report Size (1)
0x95, 0x01, // Report Count (1)
0x09, 0xCD, // Usage (Play/Pause)
0x81, 0x06, // Input (Data,Value,Relative,Bit Field)
0x0A, 0x83, 0x01, // Usage (AL Consumer Control Configuration)
0x81, 0x06, // Input (Data,Value,Relative,Bit Field)
0x09, 0xB5, // Usage (Scan Next Track)
0x81, 0x06, // Input (Data,Value,Relative,Bit Field)
0x09, 0xB6, // Usage (Scan Previous Track)
0x81, 0x06, // Input (Data,Value,Relative,Bit Field)
0x09, 0xEA, // Usage (Volume Down)
0x81, 0x06, // Input (Data,Value,Relative,Bit Field)
0x09, 0xE9, // Usage (Volume Up)
0x81, 0x06, // Input (Data,Value,Relative,Bit Field)
0x0A, 0x25, 0x02, // Usage (AC Forward)
0x81, 0x06, // Input (Data,Value,Relative,Bit Field)
0x0A, 0x24, 0x02, // Usage (AC Back)
0x81, 0x06, // Input (Data,Value,Relative,Bit Field)
0xC0 // End Collection
};
memset(inp_rep_array, 0, sizeof(inp_rep_array));
// Initialize HID Service.
p_input_report = &inp_rep_array[INPUT_REP_BUTTONS_INDEX];
p_input_report->max_len = INPUT_REP_BUTTONS_LEN;
p_input_report->rep_ref.report_id = INPUT_REP_REF_BUTTONS_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_input_report = &inp_rep_array[INPUT_REP_MOVEMENT_INDEX];
p_input_report->max_len = INPUT_REP_MOVEMENT_LEN;
p_input_report->rep_ref.report_id = INPUT_REP_REF_MOVEMENT_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_input_report = &inp_rep_array[INPUT_REP_MPLAYER_INDEX];
p_input_report->max_len = INPUT_REP_MEDIA_PLAYER_LEN;
p_input_report->rep_ref.report_id = INPUT_REP_REF_MPLAYER_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;
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 = false;
hids_init_obj.is_mouse = true;
hids_init_obj.inp_rep_count = INPUT_REPORT_COUNT;
hids_init_obj.p_inp_rep_array = inp_rep_array;
hids_init_obj.outp_rep_count = 0;
hids_init_obj.p_outp_rep_array = NULL;
hids_init_obj.feature_rep_count = 0;
hids_init_obj.p_feature_rep_array = NULL;
hids_init_obj.rep_map.data_len = sizeof(rep_map_data);
hids_init_obj.rep_map.p_data = rep_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_mouse_inp_rep_sec.cccd_wr = SEC_JUST_WORKS;
hids_init_obj.boot_mouse_inp_rep_sec.wr = SEC_JUST_WORKS;
hids_init_obj.boot_mouse_inp_rep_sec.rd = 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);
}
Other examples rely on crazy macros (usbd_hid_generic_pca10056):
APP_USBD_HID_GENERIC_GLOBAL_DEF(m_app_hid_generic,
HID_GENERIC_INTERFACE,
hid_user_ev_handler,
ENDPOINT_LIST(),
reps,
REPORT_IN_QUEUE_SIZE,
REPORT_OUT_MAXSIZE,
REPORT_FEATURE_MAXSIZE,
APP_USBD_HID_SUBCLASS_BOOT,
APP_USBD_HID_PROTO_MOUSE);
Which is the preferred approach for a generic device with an in and an out port?
I thought of taking the descriptor for a mouse which can be found in app_usb_hid_mouse_desc.h and rewriting that for a generic hid device but I'd like to know which is the preferred way. Is the macro just another level of abstraction?
