NRF52 DK and BMD-300 - different low frequency clock speeds

[TenderLoins]

I've been developing an application using the NRF52 DK and everything has been going as planned. I then made my own PCB which would take these modules by Rigado. The BMD-300 is the nRF52832 chip with all the supporting circuitry and antenna design.

Now, I made one board which worked as expected although I made a mistake thinking I could use pins 0 and 1 to drive an output while using the low frequency clock.

So I made another board which didn't have the same mistake, but now the same code running on the new board will eventually lock up (at least the logging stops). If I run the NRF52 DK and my BMD-300 board side-by-side, the BMD-300 has noticibly faster log outputs which doesn't make sense as they should both be using the same time intervals.

I did follow the instructions here to set up the internal oscillator.

Could excessive heat cause the internal oscillator to fail, or act out of specification? I need to spend some more time tinkering with it, but I was hoping that someone could point out something obvious?

Running this code below will consistently count to 137 before 'crashing' on the BMD-300 but carries on on the NRF52 DK.

extern "C" {
	#include <stdio.h>
	#include "boards.h"
	#include "app_util_platform.h"
	#include "nrf_drv_rtc.h"
	#include "nrf_drv_clock.h"
	#include "bsp.h"
	#include "app_error.h"
	#include "app_timer.h"
	#include "app_twi.h"
	#include "nrf_delay.h"
	#include "compiler_abstraction.h"

	#define NRF_LOG_MODULE_NAME "APP"
	#include "nrf_log.h"
	#include "nrf_log_ctrl.h"
}

uint8_t volatile ticks = 0;

static nrf_drv_rtc_t const m_rtc NRF_DRV_RTC_INSTANCE(0);

static void lfclk_config(void) {
	NRF_LOG_INFO("Configuring low frequency clock\r\n");
	uint32_t err_code;

	err_code = nrf_drv_clock_init();
	APP_ERROR_CHECK(err_code);

	nrf_drv_clock_lfclk_request(NULL);
}

static void rtc_handler(nrf_drv_rtc_int_type_t int_type) {
	if (int_type == NRF_DRV_RTC_INT_TICK) {
		NRF_LOG_INFO("Ticks: %i\r\n", ticks);
		ticks++;
	}
}

static void rtc_config(void) {
	NRF_LOG_INFO("Configuring RTC\r\n");
    uint32_t err_code;

    // Initialize RTC instance with default configuration.
    nrf_drv_rtc_config_t config = NRF_DRV_RTC_DEFAULT_CONFIG;
    config.prescaler = RTC_FREQ_TO_PRESCALER(32); //Set RTC frequency to 32Hz

    err_code = nrf_drv_rtc_init(&m_rtc, &config, rtc_handler);
    APP_ERROR_CHECK(err_code);

    // Enable tick event and interrupt.
    nrf_drv_rtc_tick_enable(&m_rtc, true);

    // Power on RTC instance.
    nrf_drv_rtc_enable(&m_rtc);
}

int main(void) {
	APP_ERROR_CHECK(NRF_LOG_INIT(NULL));
	NRF_LOG_INFO("\r\n\r\nStart\r\n");
	NRF_LOG_FLUSH();

	lfclk_config();
	rtc_config();

	while (true) {
		__WFI();
		NRF_LOG_FLUSH();
	}
}

[AlekseyJ]

BMD300 schematic with DC-DC converter. Try to enable DC/DC converter:

// Enable DC/DC converter
uint32_t err_code;
err_code = sd_power_dcdc_mode_set(NRF_POWER_DCDC_ENABLE);
APP_ERROR_CHECK(err_code);