cancel
Showing results for 
Search instead for 
Did you mean: 

Possible bug in RTC code

Dominik Dráb
Associate II
Posted on March 03, 2018 at 19:21

Hi, I think there is a bug in code generated by CubeMX for RTC. Problem is that if you enable wake-up timer interrupt in Cube, it is only enabled after you first power up MCU.

MX_RTC_Init

checks value of backup register to prevent RTC registers being reinitialised, but also prevents

HAL_RTC_Init

from being called.

/* RTC init function */
void MX_RTC_Init(void)
{
...
 if (HAL_RTCEx_BKUPRead(&hrtc, RTC_BKP_DR0) != 0x32F2) {
...
 if (HAL_RTC_Init(&hrtc) != HAL_OK)
 {
 _Error_Handler(__FILE__, __LINE__);
 }
 ...
 HAL_RTCEx_BKUPWrite(&hrtc, RTC_BKP_DR0, 0x32F2);
 }
}�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?

HAL_RTC_Init

normally calls

HAL_RTC_MspInit

, which enables RTC clock and enables interrupts in NVIC.

void HAL_RTC_MspInit(RTC_HandleTypeDef* rtcHandle)
{
 if(rtcHandle->Instance==RTC)
 {
...
 /* RTC clock enable */
 __HAL_RCC_RTC_ENABLE();
 
 /* RTC interrupt Init */
 HAL_NVIC_SetPriority(RTC_WKUP_IRQn, 0, 0);
 HAL_NVIC_EnableIRQ(RTC_WKUP_IRQn);
...
 }
}�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?

So, if you now reset MCU, interrupt for wake-up timer will NOT be enabled (clock for RTC will stay enabled, because it issaved in BDCR register, which is preserved after reset). I think this would occur every time device is reset without power being disconnected from Vbat.

Easy fix would be to still call

HAL_RTC_MspInit,

even if RTC registers do not need to be initialised:

/* RTC init function */
void MX_RTC_Init(void)
{
...
 if (HAL_RTCEx_BKUPRead(&hrtc, RTC_BKP_DR0) != 0x32F2) {
...
 if (HAL_RTC_Init(&hrtc) != HAL_OK)
 {
 _Error_Handler(__FILE__, __LINE__);
 }
 ...
 HAL_RTCEx_BKUPWrite(&hrtc, RTC_BKP_DR0, 0x32F2);
 }
 else
 {
 HAL_RTC_MspInit(&hrtc);
 }�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?
}�?�?�?�?�?�?�?�?�?�?�?�?�?�?
�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?

Of course we can enable interrupts at different place, but it probably would be better solution if this worked correctly.

Thanks

#wake-up #rtc
4 REPLIES 4
Pavel A.
Evangelist II
Posted on March 04, 2018 at 19:38

>

MX_RTC_Init

checks value of backup register to prevent RTC registers being reinitialised

if (HAL_RTCEx_BKUPRead(&hrtc, RTC_BKP_DR0) != 0x32F2) 

In which CubeMX version and for which chip?

No such code in F4xx library or Cube-generated main.c.

-- pa

Posted on March 04, 2018 at 19:51

I'm using STM32F746ZG MCU and CubeMX version 4.24. Firmware package is 1.9.0.

Tomasz Majoch
Associate II
Posted on March 30, 2018 at 09:31

The same for stm32f1  in firmware package 1.6.1.

Nawres GHARBI
ST Employee
Posted on May 02, 2018 at 12:15

hello,

will be fixed next release