stm32 adc+dma driver

adc.c

#include "adc.h"

#ifdef ADC_TABLE
#include "gpio.h"
#include "settings.h"

// configure all channels for 239.5 cycles per sample
#define SAMPLE_TIME		1
#define VREF			2500L

#define X(name, chan) chan,
static const uint8_t adc_chan[ADC_TOTAL_COUNT] = {
	ADC_TABLE
};
#undef X

// here raw values will be put by DMA
static volatile uint16_t adc_values[ADC_TOTAL_COUNT];

uint16_t adc_mv(adc_chan_t chan) {
	return ((((uint32_t)adc_values[chan]) << 16)/4096 * VREF) >> 16;
}

void adc_init(void) {
	uint8_t seq, chan;

	// configure clocks
	RCC->AHBENR |= RCC_AHBENR_DMA1EN;
	RCC->CFGR &= ~RCC_CFGR_ADCPRE;
	RCC->APB2ENR |= RCC_APB2ENR_ADC1EN;

	DMA1_Channel1->CPAR = (uint32_t)&(ADC1->DR);
	DMA1_Channel1->CMAR = (uint32_t)adc_values;
	DMA1_Channel1->CNDTR = ADC_TOTAL_COUNT;
	DMA1_Channel1->CCR = 
		DMA_CCR1_PL_1 |							// high priority
		DMA_CCR1_MSIZE_0 | DMA_CCR1_PSIZE_0 |	// 16-bit width
		DMA_CCR1_MINC |							// memory increment
		DMA_CCR1_CIRC;							// circular mode
	DMA1_Channel1->CCR |= DMA_CCR1_EN;

	// turn ADC on
	ADC1->CR2 |= ADC_CR2_ADON;
	
	ADC1->CR1 |= ADC_CR1_SCAN;
	ADC1->CR2 |= ADC_CR2_TSVREFE | ADC_CR2_DMA | ADC_CR2_CONT;

	// reset calibration
	ADC1->CR2 |= ADC_CR2_RSTCAL;
	while (ADC1->CR2 & ADC_CR2_RSTCAL) {}

	//start self-calibration
	ADC1->CR2 |= ADC_CR2_CAL;
	while(ADC1->CR2 & ADC_CR2_CAL) {}
	
	// set sequence length
	ADC1->SQR1 = ((ADC_TOTAL_COUNT-1) << 20) & ADC_SQR1_L;
	
	// configure each channel and fill sequence
	for (seq = 0; seq < ADC_TOTAL_COUNT; seq++) {
		chan = adc_chan[seq];

		// init corresponding pin as analog input
		if (chan <= 7)
			gpio_hw_config_pin(GPIOA, chan, GPIO_MODE_IN_ANALOG);
		else if (chan <= 9)
			gpio_hw_config_pin(GPIOB, chan-8, GPIO_MODE_IN_ANALOG);

		// add pin to sequence
		if (seq >= 12) {
			ADC1->SQR1 &= ~(0x1F << ((seq - 12) * 5));
			ADC1->SQR1 |= chan << ((seq - 12) * 5);
		}
		else if (seq >= 6) {
			ADC1->SQR2 &= ~(0x1F << ((seq - 6) * 5));
			ADC1->SQR2 |= chan << ((seq - 6) * 5);
		}
		else {
			ADC1->SQR3 &= ~(0x1F << (seq * 5));
			ADC1->SQR3 |= chan << (seq * 5);
		}

		// set sample rate
		if (chan >= 10) {
			ADC1->SMPR1 &= ~(0x07 << ((chan - 10) * 3));
			ADC1->SMPR1 |= SAMPLE_TIME << ((chan - 10) * 3);
		}
		else {
			ADC1->SMPR2 &= ~(0x07 << (chan * 3));
			ADC1->SMPR2 |= SAMPLE_TIME << (chan * 3);
		}
	}

	// start ADC
	ADC1->CR2 |= ADC_CR2_ADON;

#ifdef FEATURE_ADC_CURRENT_LIMITER
	gpio_set(BOARD_CL_EN, true);
#endif
}

#endif