BT832 BLE sample disconnect immediately

[Alexey]

All standard SDK examples disconnect immediately once I try to connect to from Android device. But when I flash the same sketch to nRF52-DK, I can connect successfully.

I use BT832 as target device and flash it with nRF52-DK. Flash and sketch validation complete successfully (ble_app_template). I can see the device "Nordic_Template" in "nRF Connect" Android application. But once I try to connect it open clean tab with no information there. 

J-Link RTT Viewer shows me the following log details:

 0> <info> app: Template example started.
 0> <info> app: Fast advertising.
 0> <info> app: Connected.
 0> <info> app: Fast advertising.
 0> <info> app: Disconnected.

I assume that some error occurs, and probably fatal enough to skip logging... But don't understand how to troubleshoot it.

I thought that maybe there is an issue in SDK, but tried on 2 of them: 12.3.0 and 14.2.0. The result is the same. 

I thought that maybe there is issue with powering BT832 directly from nRF52-DK, but the issue is still there when I power BT832 from external source. 

I also tried different ble examples from SDK (ble_app_blinky, ble_app_template, ...)

Maybe this is hardware issue with BT832 module, but strange that advertising work fine, I see the device in "nRF Connect" and the issue happen only on connection attempt.

I would appreciate any help, thanks in advance. 

P.S.

Also I noted that in BT832 datasheet says that SoC is "nRF52832 QFAA" but all files inside my _build folder have name "nrf52832_xxaa" maybe this is the case? But how to switch it?

[Sigurd]

Hi,

The disconnect reason should give us some more information about why the disconnect happened.

Could you try to print the reason when you get the disconnect event ? i.e. add this code-line under the BLE_GAP_EVT_DISCONNECTED event in ble_evt_handler()

NRF_LOG_INFO("Disconnect reason: %d",p_ble_evt->evt.gap_evt.params.disconnected.reason);

[Alexey]

Hi Sigurd. 
Here is what I get after applying extra logging:

 0> <info> app: Template example started.
 0> <info> app: Fast advertising.
 0> <info> app: Connected.
 0> <info> app: Fast advertising.
 0> <info> app: Disconnected.
 0> <info> app: Disconnect reason: 62

I tried to dig 62 code, and looks like this is ble_hci.h:

#define BLE_HCI_CONN_FAILED_TO_BE_ESTABLISHED          0x3E       /**< Connection Failed to be Established. */

Am I correct? If so, still not clear what is wrong.

[Sigurd]

What type of Android device is this? It could be a timing issue. With SDK 14.2, could you try the following configuration in sdk_config.h

// </h> 
//==========================================================

// <h> Clock - SoftDevice clock configuration

//==========================================================
// <o> NRF_SDH_CLOCK_LF_SRC  - SoftDevice clock source.
 
// <0=> NRF_CLOCK_LF_SRC_RC 
// <1=> NRF_CLOCK_LF_SRC_XTAL 
// <2=> NRF_CLOCK_LF_SRC_SYNTH 

#ifndef NRF_SDH_CLOCK_LF_SRC
#define NRF_SDH_CLOCK_LF_SRC 0
#endif

// <o> NRF_SDH_CLOCK_LF_RC_CTIV - SoftDevice calibration timer interval. 
#ifndef NRF_SDH_CLOCK_LF_RC_CTIV
#define NRF_SDH_CLOCK_LF_RC_CTIV 16
#endif

// <o> NRF_SDH_CLOCK_LF_RC_TEMP_CTIV - SoftDevice calibration timer interval under constant temperature. 
// <i> How often (in number of calibration intervals) the RC oscillator shall be calibrated
// <i>  if the temperature has not changed.

#ifndef NRF_SDH_CLOCK_LF_RC_TEMP_CTIV
#define NRF_SDH_CLOCK_LF_RC_TEMP_CTIV 2
#endif

// <o> NRF_SDH_CLOCK_LF_XTAL_ACCURACY  - External crystal clock accuracy used in the LL to compute timing windows.
 
// <0=> NRF_CLOCK_LF_XTAL_ACCURACY_250_PPM 
// <1=> NRF_CLOCK_LF_XTAL_ACCURACY_500_PPM 
// <2=> NRF_CLOCK_LF_XTAL_ACCURACY_150_PPM 
// <3=> NRF_CLOCK_LF_XTAL_ACCURACY_100_PPM 
// <4=> NRF_CLOCK_LF_XTAL_ACCURACY_75_PPM 
// <5=> NRF_CLOCK_LF_XTAL_ACCURACY_50_PPM 
// <6=> NRF_CLOCK_LF_XTAL_ACCURACY_30_PPM 
// <7=> NRF_CLOCK_LF_XTAL_ACCURACY_20_PPM 

#ifndef NRF_SDH_CLOCK_LF_XTAL_ACCURACY
#define NRF_SDH_CLOCK_LF_XTAL_ACCURACY 1
#endif

[Alexey]

Sigurd, thanks, this magic numbers helped me! Now it works fine. 
Could you please advice if I can read about this magic numbers or overall about sdk_config.h configuration strategy somewhere?