使用STM32的PID控制舵机的程序的实例

以下是使用STM32控制舵机的PID程序示例：

#include "stm32f10x.h"
#include "stm32f10x_tim.h"
#include "stdio.h"

#define TIM_PERIOD 65535

volatile uint16_t timerCount = 0;
volatile uint16_t dutyCycle = 0;
uint16_t desiredPosition = 500;
uint16_t currentPosition = 500;
float kp = 0.5;
float ki = 0.1;
float kd = 0.1;
float error = 0;
float lastError = 0;
float integral = 0;
float derivative = 0;
uint8_t pidFlag = 0;

void TIM3_IRQHandler(void)
{
    if (TIM_GetITStatus(TIM3, TIM_IT_Update) == SET)
    {
        TIM_ClearITPendingBit(TIM3, TIM_IT_Update);
        timerCount++;
        if (timerCount >= TIM_PERIOD)
        {
            timerCount = 0;
            pidFlag = 1;
        }
        if (timerCount >= dutyCycle) GPIO_ResetBits(GPIOB, GPIO_Pin_0);
        else GPIO_SetBits(GPIOB, GPIO_Pin_0);
    }
}

void Delay(__IO uint32_t nCount)
{
    for (; nCount != 0; nCount--);
}

void PIDControl()
{
    error = desiredPosition - currentPosition;
    integral += error;
    derivative = error - lastError;
    lastError = error;
    dutyCycle = kp*error + ki*integral + kd*derivative;
    if (dutyCycle >= TIM_PERIOD) dutyCycle = TIM_PERIOD;
    if (dutyCycle < 0) dutyCycle = 0;
}

int main(void)
{
    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    NVIC_InitTypeDef NVIC_InitStructure;
    GPIO_InitTypeDef GPIO_InitStructure;

    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOB, &GPIO_InitStructure);

    TIM_TimeBaseStructure.TIM_Period = TIM_PERIOD - 1;
    TIM_TimeBaseStructure.TIM_Prescaler = 72 - 1;
    TIM_TimeBaseStructure.TIM_ClockDivision = 0;
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

    NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);

    TIM_ITConfig(TIM3, TIM_IT_Update, ENABLE);
    TIM_Cmd(TIM3, ENABLE);

    while (1)
    {
        if (pidFlag)
        {
            pidFlag = 0;
            currentPosition = TIM_GetCounter(TIM3);
            PIDControl();
        }
        Delay(5000);
    }
}

在此示例中，使用STM32的Timer3来控制舵机，GPIOB0用作输出。程序中使用TIM_PERIOD定义了Timer3的最大计数值，该值为65535。在TIM3_IRQHandler中读取计数器值和dutyCycle的值，并切换GPIOB0的状态以产生PWM信号。PIDControl函数计算出新的dutyCycle的值，并以kp，ki和kd的权重求和。程序的主循环通过pidFlag标志间隔5000个系统时钟周期来调用PIDControl函数。 在此程序中，kp，ki和kd的值是手动设置的，用户可以根据需要进行调整，以获得最佳控制效果。