Cortex _M4按键控制pwm占空比输出
时间: 2024-01-29 18:04:18 浏览: 25
首先,你需要连接一个PWM输出引脚到电机或其他装置上,以控制它的转速或运动。然后,你需要连接一个按键到单片机的GPIO引脚上,以便输入按键状态。以下是一个简单的代码实现,可以让你通过按键来控制PWM占空比输出:
```c
#include "stm32f4xx.h"
int main(void) {
GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
// 开启外设时钟
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
// 配置GPIO引脚为输入模式
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
GPIO_Init(GPIOA, &GPIO_InitStructure);
// 配置PWM输出引脚
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_Init(GPIOA, &GPIO_InitStructure);
// 将引脚与定时器关联
GPIO_PinAFConfig(GPIOA, GPIO_PinSource5, GPIO_AF_TIM2);
// 初始化定时器
TIM_TimeBaseStructure.TIM_Period = 8399; // PWM频率为10kHz
TIM_TimeBaseStructure.TIM_Prescaler = 0;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);
// 配置PWM输出通道
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
TIM_OCInitStructure.TIM_Pulse = 0;
TIM_OC2Init(TIM2, &TIM_OCInitStructure);
TIM_OC2PreloadConfig(TIM2, TIM_OCPreload_Enable);
// 启动定时器
TIM_Cmd(TIM2, ENABLE);
while (1) {
// 检查按键状态
if (GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_0) == RESET) {
// 按键按下,增加PWM占空比
uint16_t pulse = TIM_GetCapture2(TIM2);
if (pulse < 8400) pulse++;
TIM_SetCompare2(TIM2, pulse);
// 等待按键释放
while (GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_0) == RESET);
}
}
}
```
在这个例子中,我们使用了TIM2的第二个通道来生成PWM输出,频率为10kHz,占空比默认为0。当按下按键时,我们将占空比逐步增加,直到达到最大值为100%。当占空比达到100%时,再次按下按键将会重新从0开始。