[nrf52] Fix millis() hang on OVERFLOW reached

Author: facchinm

variants/ARDUINO_NANO33BLE/variant.cpp

@@ -57,6 +57,8 @@ extern "C" {
   }
 }
 
+#include "nrf_rtc.h"
+
 void initVariant() {
   // turn power LED on
   pinMode(LED_PWR, OUTPUT);
@@ -67,6 +69,11 @@ void initVariant() {
   CoreDebug->DEMCR = 0;
   NRF_CLOCK->TRACECONFIG = 0;
 
+  // FIXME: bootloader enables interrupt on COMPARE[0], which we don't handle
+  // Disable it here to avoid getting stuck when OVERFLOW irq is triggered
+  nrf_rtc_event_disable(NRF_RTC1, NRF_RTC_INT_COMPARE0_MASK);
+  nrf_rtc_int_disable(NRF_RTC1, NRF_RTC_INT_COMPARE0_MASK);
+
   // FIXME: always enable I2C pullup and power @startup
   // Change for maximum powersave
   pinMode(PIN_ENABLE_SENSORS_3V3, OUTPUT);