Problem detecting external crystal oscillator in custom nrf52832

[Kapil Rawat]

Hi 

I'm facing problem to detect external crystal oscillator in my custom nrf52832 board's. I'm think it is not connection issue as I'm facing same issue in other 9 boards as well.

When I'm using internal RC (nrf_sdh.c file) BLE blinky example is working fine. 

    nrf_clock_lf_cfg_t const clock_lf_cfg =
    {
        
        .source        = NRF_SDH_CLOCK_LF_SRC,
        .rc_ctiv       = NRF_SDH_CLOCK_LF_RC_CTIV,
        .rc_temp_ctiv  = NRF_SDH_CLOCK_LF_RC_TEMP_CTIV,
        #ifdef S140
            .xtal_accuracy = NRF_SDH_CLOCK_LF_XTAL_ACCURACY
        #else
            .accuracy      = NRF_SDH_CLOCK_LF_XTAL_ACCURACY
        #endif

        /* Working fine
              .source = 0,
              .rc_ctiv = 16,
              .rc_temp_ctiv = 2,
              .accuracy = 7 
        */

    };

 

Schematic 

Board Layout

Assembled PCB

We also check crystal orientation 1st and 3rd pins need to be connect while 2 (cut pad) and 4 NC. value of C1 and C2 are 12pF.   

[jmag999]

You are adjusting the LF (low frequency = 32KHz) clock, but your schematic shows a 32MHz (the high frequency clock).

[Andreas]

Hi,

 

clock_lf_cfg contains the LF clock configuration, while the HW images you uploaded show the 32 MHz crystal, used for the HF clock. You need the 32.768 kHz crystal on XL1 and XL2 to use crystal as source for LF clock, or you need to use NRF_CLOCK_LF_SRC_SYNTH to synthesize it from the 32MHz crystal. The fact that the BLE blinky example runs with internal RC is proof that the 32 MHz crystal is functioning properly, the radio will not work without it.

 

Best regards,

Andreas