STM32GENERIC/STM32/cores/arduino/stm32/stm32_ADC.c

/**
 * Implementation of Arduino methods:
 * analogRead(): https://www.arduino.cc/en/Reference/AnalogRead
 *
 * TODO actually create stm32_analog_in_XX.c files for the different variants. This is getting too compicated
 *
 * TODO improve performance by saving if the pin was configured for analog, and do not configure again.
 *   also deconfigure from pinMode in this case
 * TODO implement analogReadResolution
 * TODO F1 has no resolution, map to arduino default 10 bits
 * TODO check if ClockPrescaler can always be set to ADC_CLOCK_SYNC_PCLK_DIV2
 */

#include "stm32_gpio_af.h"

void stm32_adc_init(ADC_HandleTypeDef *handle);

#ifdef ADC_CLOCK_SYNC_PCLK_DIV2
#define ADC_CLOCK_DIV ADC_CLOCK_SYNC_PCLK_DIV2
#elif defined(ADC_CLOCK_ASYNC_DIV1)
#define ADC_CLOCK_DIV ADC_CLOCK_ASYNC_DIV1
#elif defined(ADC_CLOCKPRESCALER_PCLK_DIV2)
#define ADC_CLOCK_DIV ADC_CLOCKPRESCALER_PCLK_DIV2
#else
#error "Unknown clock"
#endif


int analogRead(uint8_t pin) {
    static ADC_HandleTypeDef handle = {};

    GPIO_InitTypeDef GPIO_InitStruct;
    GPIO_InitStruct.Pin = port_pin_list[pin].pin_mask;
    GPIO_InitStruct.Mode = GPIO_MODE_ANALOG;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    HAL_GPIO_Init(port_pin_list[pin].port, &GPIO_InitStruct);

    if (handle.Instance == NULL) {
        #ifdef __HAL_RCC_ADC1_CLK_ENABLE
        __HAL_RCC_ADC1_CLK_ENABLE();
        #endif
        #ifdef __HAL_RCC_ADC_CLK_ENABLE
        __HAL_RCC_ADC_CLK_ENABLE();
        #endif
        
        handle.Instance = ADC1;
        handle.Init.ScanConvMode = DISABLE;
        handle.Init.ContinuousConvMode = ENABLE;
        handle.Init.DiscontinuousConvMode = DISABLE;
        handle.Init.DataAlign = ADC_DATAALIGN_RIGHT;

        #ifdef STM32L0
            handle.Init.SamplingTime = ADC_SAMPLETIME_13CYCLES_5;
        #endif

        #if !defined(STM32L0) && !defined(STM32F0)
            handle.Init.NbrOfConversion = 1;
        #endif

        #ifdef ADC_EOC_SINGLE_CONV
            handle.Init.EOCSelection = ADC_EOC_SINGLE_CONV;
        #endif

        #ifdef STM32F1
            handle.Init.ExternalTrigConv = ADC_SOFTWARE_START;
        #else
            handle.Init.ClockPrescaler = ADC_CLOCK_DIV;
            handle.Init.Resolution = ADC_RESOLUTION_12B;
        #endif

        HAL_ADC_Init(&handle);

    }

    ADC_ChannelConfTypeDef sConfig;
    sConfig.Channel = stm32_adc1_get_channel(port_pin_list[pin].port, port_pin_list[pin].pin_mask);
    sConfig.Rank = 1;

    #if STM32L0
        //in handle
    #elif defined(ADC_SAMPLETIME_15CYCLES)
        sConfig.SamplingTime = ADC_SAMPLETIME_15CYCLES;
    #elif defined(ADC_SAMPLETIME_13CYCLES_5)
        sConfig.SamplingTime = ADC_SAMPLETIME_13CYCLES_5;
    #elif defined(ADC_SAMPLETIME_19CYCLES_5)
        sConfig.SamplingTime = ADC_SAMPLETIME_19CYCLES_5;
    #elif defined(ADC_SAMPLETIME_16CYCLES)
        sConfig.SamplingTime = ADC_SAMPLETIME_16CYCLES;
    #elif defined(ADC_SAMPLETIME_12CYCLES_5)
        sConfig.SamplingTime = ADC_SAMPLETIME_12CYCLES_5;
    #else
        #error "unknown sampleing time"
    #endif

    HAL_ADC_ConfigChannel(&handle, &sConfig);

    HAL_ADC_Start(&handle);

    if (HAL_ADC_PollForConversion(&handle, 1000) != HAL_OK) {
            return 0;
    }

    return HAL_ADC_GetValue(&handle) >> 2;
}