Error 8 (0x8): GATT CONN TIMEOUT on nRF52805

RE: Error 8 (0x8): GATT CONN TIMEOUT on nRF52805

run_ar — Fri, 09 Jul 2021 22:28:41 GMT

Hi,

A good tip for debugging is to add the debug flag to preprocessor symbols and place a breakpoint in the app_error_fault_handler, that way you can see if there are any app errors.

As for the lfrc, I think using the LFRC should be fine. The TWI clock is derived from the HFXO, but you might want to start the hfxo manually (by calling sd_clock_hfclk_request) for TWI, if not the SD might toggle it on/off (I am not to familiar with the driver, so it might be doing that already, but good to check).

Fyi, we are beginning summer vacations, so you might get longer response times. I will be ooo for the next 4 weeks, you might want to open a new case if you cannot see any asserts.

RE: Error 8 (0x8): GATT CONN TIMEOUT on nRF52805

StevenW807 — Fri, 09 Jul 2021 08:20:30 GMT

Hi run_ar, thank you very much for your support.

1)

I have 2 PCB boards: 1 board has the nRF52805, another PCB has TWI sensors. I'm using 2 ADC and 1 TWI and BLE.

2)

For the application log, do you mean to use RTT Viewer? I have enabled RTT and LOG functions in sdk_config.h, but nothing shows on the RTT Viewer.

(Note: Because it's a BLE application, we cannot use SEGGER debugger function)

What do you mean by "debugger"?

3)

Because I don't have an external clock on my PCB, so I used the internal RC oscillator (32.768kHz). However, in my code, I used:

SAADC_SAMPLE_RATE = 20ms (Will it has an accuracy issue? I guess not, right?)

many types of BLE intervals = 64ms, 20ms, 30ms, etc (Will it has an accuracy issue? I guess not, right?)

timer_config.frequency = NRF_TIMER_FREQ_31250Hz; (Will it has an accuracy issue? I guess not, right?)

TWI uses 400kHz clock (Higher frequency than RC oscillator, I guess it causes the code issue)

And in future, I will use 14-bit oversampling for 2 SAADC.

Could I solve the above clock issues with internal clocks?

Thanks again!

RE: Error 8 (0x8): GATT CONN TIMEOUT on nRF52805

run_ar — Thu, 08 Jul 2021 11:25:06 GMT

Hi,

Thank you for the nRF connect log, Unfortunately it only shows me that there is a timeout, so it doesn't tell me anything about what is happening in the application. Could you capture an application log? or could you connect a debugger and check if you are getting any application errors? reboots? or any other issues?

could you provide a project for recreating the issue? or the part of the code where you try to send TWI data?

RE: Error 8 (0x8): GATT CONN TIMEOUT on nRF52805

StevenW807 — Thu, 08 Jul 2021 07:15:05 GMT

Thanks run_ar, Yes, all above 3 parameters are 0 (RC ocillator)

NRFX_CLOCK_CONFIG_LF_SRC = 0
CLOCK_CONFIG_LF_SRC = 0
NRF_SDH_CLOCK_LF_SRC = 0

I'm using a 400kHz TWI master, 2 ADC channels and BLE (i.e. Send TWI and ADC data via BLE). Although I could connect and see all data on the nRF Connect mobile App, BLE will disconnect in a few seconds.

__STATIC_INLINE void data_handler(uint16_t data1, uint16_t data2)
{
     // Same data calculations and filters
}


.
.
.


void saadc_callback(nrf_drv_saadc_evt_t const * p_event)
{
    if (p_event->type == NRF_DRV_SAADC_EVT_DONE)
    {
        ret_code_t err_code;
        uint16_t bytes_to_send;
     
        // set buffers
        err_code = nrf_drv_saadc_buffer_convert(p_event->data.done.p_buffer, SAADC_SAMPLES_IN_BUFFER);
        APP_ERROR_CHECK(err_code);
						
        // Get 2 ADC values
        adc_data_1 = p_event->data.done.p_buffer[0];
        adc_data_2 = p_event->data.done.p_buffer[1];

        // convert ADC raw data to the real data

        uint8_t nus_string[100];
        bytes_to_send = sprintf(nus_string,"\%.2f     %.2f    %.2f", adc_data_converted_1, adc_data_converted_2, twi_data1);
        
        err_code = ble_nus_data_send(&m_nus, nus_string, &bytes_to_send, m_conn_handle);
        if ((err_code != NRF_ERROR_INVALID_STATE) && (err_code != NRF_ERROR_NOT_FOUND))
        {
            APP_ERROR_CHECK(err_code);
        }
	
        m_adc_evt_counter++;
    }
}

Here is nRF Connect Mobile App debug log:

devzone.nordicsemi.com/.../Log-2021_2D00_07_2D00_08-16_5F00_47_5F00_39.txt

Using the above code, BLE works fine if I only send ADC data (doesn't include TWI data). Why is that, please? What's the solution? Thank you!

RE: Error 8 (0x8): GATT CONN TIMEOUT on nRF52805

run_ar — Tue, 06 Jul 2021 13:17:37 GMT

Hi,

I could not see anything obvious from the sniffer log. Could you check that all sdk_config entries are configured to use the RC?

NRFX_CLOCK_CONFIG_LF_SRC
CLOCK_CONFIG_LF_SRC
NRF_SDH_CLOCK_LF_SRC

Also, could you try to get an application log? i.e. do you know if here are any errors or asserts in the application once it is disconnected?