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stm32/{adc,machine_adc}: Change ADC clock and sampling time for F0 MCUs. 

STM32F0 has PCLK=48MHz and maximum ADC clock is 14MHz so use PCLK/4=12MHz
to stay within spec of the ADC peripheral.  In pyb.ADC set common sampling
time to approx 4uS for internal and external sources.  In machine.ADC
reduce sample time to approx 1uS for external source, leave internal at
maximum sampling time.
This commit is contained in:
Chris Mason 2019-09-27 14:27:51 +10:00 committed by Damien George
parent a09fd04758
commit 0096041c99
2 changed files with 10 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
ports/stm32/adc.c
View File

@ -241,7 +241,13 @@ STATIC void adcx_init_periph(ADC_HandleTypeDef *adch, uint32_t resolution) {
adch->Init.EOCSelection = ADC_EOC_SINGLE_CONV;
adch->Init.ExternalTrigConv = ADC_SOFTWARE_START;
adch->Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_NONE;
#if defined(STM32F0) || defined(STM32F4) || defined(STM32F7)
#if defined(STM32F0)
adch->Init.ClockPrescaler = ADC_CLOCK_SYNC_PCLK_DIV4; // 12MHz
adch->Init.ScanConvMode = DISABLE;
adch->Init.DataAlign = ADC_DATAALIGN_RIGHT;
adch->Init.DMAContinuousRequests = DISABLE;
adch->Init.SamplingTimeCommon = ADC_SAMPLETIME_55CYCLES_5; // ~4uS
#elif defined(STM32F4) || defined(STM32F7)
adch->Init.ClockPrescaler = ADC_CLOCK_SYNC_PCLK_DIV2;
adch->Init.ScanConvMode = DISABLE;
adch->Init.DataAlign = ADC_DATAALIGN_RIGHT;
@ -266,10 +272,6 @@ STATIC void adcx_init_periph(ADC_HandleTypeDef *adch, uint32_t resolution) {
#error Unsupported processor
#endif
#if defined(STM32F0)
adch->Init.SamplingTimeCommon = ADC_SAMPLETIME_71CYCLES_5;
#endif
HAL_ADC_Init(adch);
#if defined(STM32H7)
@ -309,7 +311,7 @@ STATIC void adc_config_channel(ADC_HandleTypeDef *adc_handle, uint32_t channel)
sConfig.Channel = channel;
sConfig.Rank = 1;
#if defined(STM32F0)
sConfig.SamplingTime = ADC_SAMPLETIME_71CYCLES_5;
sConfig.SamplingTime = ADC_SAMPLETIME_55CYCLES_5;
#elif defined(STM32F4) || defined(STM32F7)
sConfig.SamplingTime = ADC_SAMPLETIME_15CYCLES;
#elif defined(STM32H7)

4
ports/stm32/machine_adc.c
View File

@ -49,7 +49,7 @@
#endif
#if defined(STM32F0)
#define ADC_SAMPLETIME_DEFAULT ADC_SAMPLETIME_71CYCLES_5
#define ADC_SAMPLETIME_DEFAULT ADC_SAMPLETIME_13CYCLES_5
#define ADC_SAMPLETIME_DEFAULT_INT ADC_SAMPLETIME_239CYCLES_5
#elif defined(STM32F4) || defined(STM32F7)
#define ADC_SAMPLETIME_DEFAULT ADC_SAMPLETIME_15CYCLES
@ -126,7 +126,7 @@ STATIC void adc_config(ADC_TypeDef *adc, uint32_t bits) {
// Configure clock mode
#if defined(STM32F0)
adc->CFGR2 = 1 << ADC_CFGR2_CKMODE_Pos; // PCLK/2 (synchronous clock mode)
adc->CFGR2 = 2 << ADC_CFGR2_CKMODE_Pos; // PCLK/4 (synchronous clock mode)
#elif defined(STM32F4) || defined(STM32F7) || defined(STM32L4)
ADCx_COMMON->CCR = 0; // ADCPR=PCLK/2
#elif defined(STM32H7)