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stm32/adc: Fix ADC clock prescaler for G4 MCUs.

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For STM32G4, ADC clock frequency should be equal or less than 60MHz.
To satisfy this specification, ADC clock prescaler should be equal or
greater than 4 (For example, NUCLEO_G474RE runs 170MHz).

In addition, to obtain accurate internal channel value,
the ADC clock prescaler is set to 16 because vbat needs at least 12us
(16/170*247.5=23.3us).

Signed-off-by: Yuuki NAGAO <wf.yn386@gmail.com>
This commit is contained in:
Yuuki NAGAO 2023-07-08 10:46:01 +09:00 committed by Damien George
parent ec9ea97413
commit de8035b510
1 changed files with 4 additions and 0 deletions
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4
ports/stm32/adc.c
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@ -344,7 +344,11 @@ STATIC void adcx_init_periph(ADC_HandleTypeDef *adch, uint32_t resolution) {
adch->Init.DataAlign = ADC_DATAALIGN_RIGHT; adch->Init.DataAlign = ADC_DATAALIGN_RIGHT;
adch->Init.DMAContinuousRequests = DISABLE; adch->Init.DMAContinuousRequests = DISABLE;
#elif defined(STM32G0) || defined(STM32G4) || defined(STM32H5) || defined(STM32L4) || defined(STM32WB) #elif defined(STM32G0) || defined(STM32G4) || defined(STM32H5) || defined(STM32L4) || defined(STM32WB)
#if defined(STM32G4)
adch->Init.ClockPrescaler = ADC_CLOCK_ASYNC_DIV16;
#else
adch->Init.ClockPrescaler = ADC_CLOCK_ASYNC_DIV1; adch->Init.ClockPrescaler = ADC_CLOCK_ASYNC_DIV1;
#endif
adch->Init.ScanConvMode = ADC_SCAN_DISABLE; adch->Init.ScanConvMode = ADC_SCAN_DISABLE;
adch->Init.LowPowerAutoWait = DISABLE; adch->Init.LowPowerAutoWait = DISABLE;
adch->Init.Overrun = ADC_OVR_DATA_PRESERVED; adch->Init.Overrun = ADC_OVR_DATA_PRESERVED;