Problem with HAL RTC libraries

[JFels]

In the function:

HAL_RTCEx_DisableBypassShadow()

There is a cast to uint8_t in the line that resets the bit

hrtc->Instance->CR &= ((uint8_t)~RTC_CR_BYPSHAD);

This causes the upper 24 bits of this configuration register to be cleared to 0s when called. Everywhere else I looked in the HAL RTC code when resetting bits in this register it is using a (uint32_t) cast.

This was found in the library:

STM32Cube_FW_L4_V1.7.0

as well as

STM32Cube_FW_F4_V1.21.0

[Tesla DeLorean]

Good catch! @STOne-32​ @Amel NASRI​ 

[Imen.D · Accepted solution]

Hello @JFels​ ,

Thank you for highlighting this. This issue is raised internally.

With Regards,

Imen

[ravo]

Dears,

I found some "strange" issues when calling these functions - after calling these functions corrupted alarms, CALIB_OUT signal. Was these issues really solved? I don't think.

Same as older report from 2015 https://community.st.com/t5/stm32-mcus-products/rtc-out-lost-when-calling-hal-rtcex-enablebypassshadow-for-hal/td-p/433472

I have looked in STM32Cube_FW_F4_V1.28.0 and still there exists this bug with conversion (uint8_t) before writing to 32 bit register:

HAL_RTCEx_DisableBypassShadow in stm32f4xx_hal_rtc_ex.c
/* Reset the BYPSHAD bit */
hrtc->Instance->CR &= (uint8_t)~RTC_CR_BYPSHAD;

Calculation example:

0xFFFFFFFF &= ~ 0x20 will produce 0x000000DF - "upper 24 bits are zeroed". But maybe I have the wrong compiler :(

I hope that it will be corrected a bit sooner.

Best Regards

Radim