以下是基于STM32写的呼吸灯代码:
```
#include "stm32f10x.h"
#define LED_PIN GPIO_Pin_13
#define LED_PORT GPIOC
void delay(uint32_t time) {
while (time--);
}
int main(void) {
GPIO_InitTypeDef GPIO_InitStructure;
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC, ENABLE);
GPIO_InitStructure.GPIO_Pin = LED_PIN;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(LED_PORT, &GPIO_InitStructure);
uint16_t brightness = 0;
uint8_t direction = 1;
while (1) {
GPIO_WriteBit(LED_PORT, LED_PIN, (brightness > 0));
if (direction == 1) {
brightness++;
if (brightness >= 1000) {
direction = 0;
}
} else {
brightness--;
if (brightness <= 0) {
direction = 1;
}
}
delay(5000);
}
}
```
该代码使用了STM32的定时器来控制LED的亮度,通过改变亮度值的大小和方向来实现呼吸灯效果。在每次循环中,先将LED的状态设置为当前亮度是否大于0,然后根据方向调整亮度值,并延迟一段时间后再进行下一次循环。