STM32 标准库函数解析 PPM 信号 - 代码示例

#include "stm32f4xx.h"

#define PPM_CHANNEL_COUNT 8 #define PPM_FRAME_LENGTH 30000

volatile uint16_t ppm[PPM_CHANNEL_COUNT];

void TIM2_IRQHandler(void) { static uint8_t current_channel = 0; static uint16_t last_time = 0; uint16_t current_time = TIM_GetCapture1(TIM2); uint16_t pulse_width = current_time - last_time;

if (pulse_width > 1000) {
    current_channel = 0; // Start of new frame
} else {
    ppm[current_channel] = pulse_width;
    current_channel++;
    if (current_channel >= PPM_CHANNEL_COUNT) {
        current_channel = 0; // End of frame
    }
}

last_time = current_time;

TIM_ClearITPendingBit(TIM2, TIM_IT_CC1);

}

int main(void) { // Initialize GPIO and timer GPIO_InitTypeDef GPIO_InitStructure; TIM_TimeBaseInitTypeDef TIM_TimeBase_InitStructure; TIM_ICInitTypeDef TIM_IC_InitStructure;

RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
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);

GPIO_PinAFConfig(GPIOA, GPIO_PinSource0, GPIO_AF_TIM2);

TIM_TimeBase_InitStructure.TIM_Prescaler = 83; // Assuming 84 MHz clock, 1 MHz timer clock
TIM_TimeBase_InitStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBase_InitStructure.TIM_Period = PPM_FRAME_LENGTH - 1;
TIM_TimeBase_InitStructure.TIM_ClockDivision = TIM_CKD_DIV1;
TIM_TimeBaseInit(TIM2, &TIM_TimeBase_InitStructure);

TIM_IC_InitStructure.TIM_Channel = TIM_Channel_1;
TIM_IC_InitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;
TIM_IC_InitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
TIM_IC_InitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
TIM_IC_InitStructure.TIM_ICFilter = 0x0;
TIM_ICInit(TIM2, &TIM_IC_InitStructure);

TIM_ITConfig(TIM2, TIM_IT_CC1, ENABLE);
NVIC_EnableIRQ(TIM2_IRQn);

TIM_Cmd(TIM2, ENABLE);

while (1) {
    // Process ppm array here
}

}