STM32G0B1RC LSCO output on PA2 even the LSCOEN=0

[GEORGE SANDLER]

Started using PA2 pin as a ADC input and found that the input voltage get corrupted with LSCO output. Happens not always, but very often. Powering board down and up sometimes fixes the problem, sometimes not.

The LSCO output enable control bit LSCOEN is 0. Calling HAL_RCCEx_DisableLSCO() doesn't help.

Thanks,

George

[waclawek.jan · Accepted solution]

Cube/HAL is open source, so you can always observe what do its function do - or what they don't.

For example, HAL_RTCEx_DeactivateCalibrationOutPut() uses __HAL_RTC_WRITEPROTECTION_DISABLE macro, but it does not perform the general backup domain enable through setting PWR_CR1.DBP, so its functionality depends on whether some surrounding/preceding code unlocks the backup domain and leaves it unlocked.

Nonetheless, you may want to follow the errata recommendation and upon suspected brownout perform a backup-domain reset before starting to configure RTC.

JW