Problem with crystal and custom board

[Antonio]

Hi, i build my own custom board with a NRF52832, i'm having problem with the softdevice (i think so)... my code is base on BLE s132 central and peripheral...

I developed the code and test on a NRF52 DK and it worked all right, everything was ok..

I test a simple code (toggle Leds) in my custom board and it worked ok (No softdevice)

I load the softdevice s130 and the code (central device) and my custom board get reset and start again.. I can see when the scanning led turn on and inmediatily restart and start again..

I'm going to paste my init code. Hope you can help me.

MAIN:

    int main(void)
    {
    
    	  entrada3=1;
    	  entrada4= 1;
    
        ret_code_t err_code;
  
        leds_init();
    	         
   
    		ble_stack_init();
    	 
        setear_direccion_central();
   
        db_discovery_init();
   	
    	  nus_c_init();
    		
   // Start scanning for peripherals and initiate connection to devices which
       scan_start();
     	for (;;)
    	{
    		// Wait for BLE events.
    			power_manage();
    				 }			 
    	
        }

BLE_STACK_INIT()

static void ble_stack_init(void)
{
   ret_code_t err_code;

    nrf_clock_lf_cfg_t clock_lf_cfg = NRF_CLOCK_LFCLKSRC;
    // Initialize the SoftDevice handler module.
	
	// THE CODE STOPS WHEN THE LINE DOWN is EXCECUTED.

    SOFTDEVICE_HANDLER_INIT(&clock_lf_cfg, NULL);

    ble_enable_params_t ble_enable_params;
    err_code = softdevice_enable_get_default_config(CENTRAL_LINK_COUNT,
                                                    PERIPHERAL_LINK_COUNT,
                                                    &ble_enable_params);
    APP_ERROR_CHECK(err_code);

    //Check the ram settings against the used number of links
    CHECK_RAM_START_ADDR(CENTRAL_LINK_COUNT,PERIPHERAL_LINK_COUNT);

    // Enable BLE stack.
    err_code = softdevice_enable(&ble_enable_params);
	    APP_ERROR_CHECK(err_code);

    // Register with the SoftDevice handler module for BLE events.
    err_code = softdevice_ble_evt_handler_set(ble_evt_dispatch);
	    APP_ERROR_CHECK(err_code);
}

NRF_CLOCK_LFCLKSRC:

#define NRF_CLOCK_LFCLKSRC      {.source        = NRF_CLOCK_LF_SRC_XTAL ,            \
                                 .rc_ctiv       = 0,                                \
                                 .rc_temp_ctiv  = 0,                                \
                                 .xtal_accuracy = NRF_CLOCK_LF_XTAL_ACCURACY_20_PPM}

SCAN_START()

static void scan_start(void)
{
	  scantime++;
	  
    ret_code_t err_code;
    int8_t tx_power =-40;
    err_code =	sd_ble_gap_scan_stop();
		
    // It is okay to ignore this error since we are stopping the scan anyway.
    if (err_code != NRF_ERROR_INVALID_STATE)
    {
        APP_ERROR_CHECK(err_code);
    }
    sd_ble_gap_tx_power_set(tx_power);
		
    err_code = sd_ble_gap_scan_start(&m_scan_param);
		APP_ERROR_CHECK(err_code);
			
		led_scanning();

}

[Ole Bauck]

Use this config:

#define NRF_CLOCK_LFCLKSRC      {.source        = NRF_CLOCK_LF_SRC_RC ,            \
                                 .rc_ctiv       = 16,                                \
                                 .rc_temp_ctiv  = 2,                                \
                                 .xtal_accuracy = 0}

Ref nrf_clock_lf_cfg_t

However I do not think that the problem is with the LF crystal, then the code should have stopped in SOFTDEVICE_HANDLER_INIT(&clock_lf_cfg, NULL).

If the load capacitance of the crystal is 8pF, then 12 pF is the correct value for the capacitor for each leg ((12pF+4pF)/2 = 8pF, 4pF is the pin capacitance).