stm32/powerctrl: Disable RTC write protection before changing flags.
@@ -689,6 +689,10 @@ void powerctrl_enter_standby_mode(void) {
// save RTC interrupts
uint32_t save_irq_bits = RTC->CR & CR_BITS;
+ // disable register write protection
+ RTC->WPR = 0xca;
+ RTC->WPR = 0x53;
+
// disable RTC interrupts
RTC->CR &= ~CR_BITS;
@@ -714,6 +718,9 @@ void powerctrl_enter_standby_mode(void) {
// enable previously-enabled RTC interrupts
RTC->CR |= save_irq_bits;
+ // enable register write protection
+ RTC->WPR = 0xff;
+
#if defined(STM32F7)
// Enable the internal (eg RTC) wakeup sources
// See Errata 2.2.2 "Wakeup from Standby mode when the back-up SRAM regulator is enabled"
