pwm.c

Explains how to read from ADC and control the PWM.

/*
 * This example shows how to read from ADC and control the PWM.
 */

#include <stm32f4xx.h>
#include <carme.h>
#include <carme_io2.h>

#define PWM_HZ      2000        /* PWM counter speed    */
#define PWM_PERIOD  100         /* PWM period length    */
#define ADC_MAX     1023        /* maximal ADC value    */

int main(void) {

    TIM_TimeBaseInitTypeDef TIM_TimeBaseStruct;
    uint16_t value;
    uint16_t prescaler;

    CARME_IO2_Init();

    prescaler = (uint16_t) ((SystemCoreClock / 2) / PWM_HZ) - 1;
    TIM_TimeBaseStruct.TIM_Prescaler = prescaler;
    TIM_TimeBaseStruct.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseStruct.TIM_Period = PWM_PERIOD - 1;
    TIM_TimeBaseStruct.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseStruct.TIM_RepetitionCounter = 0;
    CARME_IO2_PWM_Settings(&TIM_TimeBaseStruct);
    CARME_IO2_GPIO_Out_Settings(CARME_IO2_GPIO_OUT_PIN0, CARME_IO2_GPIO_OUT_MODE_PWM);

    for (;;) {
        CARME_IO2_ADC_Get(CARME_IO2_ADC_PORT0, &value);
        CARME_IO2_PWM_Set(CARME_IO2_PWM0, value * PWM_PERIOD / ADC_MAX);
    }
    return 0;
}