基于stm32，航模遥控器SBUS协议，控制L29N电机驱动

基于STM32的航模遥控器可以通过SBUS协议来接收来自遥控器的信号，然后通过PWM信号控制L29N电机驱动模块。下面是一个简单的代码示例：

#include "stm32f1xx_hal.h"
#include "stdio.h"
#include "stdlib.h"

#define SBUS_BUFFER_SIZE 25
#define PWM_MIN 1000
#define PWM_MAX 2000
#define PWM_MID 1500

UART_HandleTypeDef huart1;

uint8_t sbus_buffer[SBUS_BUFFER_SIZE];
uint16_t sbus_channels[18];

void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart) {
  static uint8_t buffer_index = 0;
  if (huart->Instance == USART1) {
    if (buffer_index == 0 && sbus_buffer[0] != 0x0F) {
      return;
    }
    sbus_buffer[buffer_index++] = huart->Instance->DR;
    if (buffer_index == SBUS_BUFFER_SIZE) {
      buffer_index = 0;
      for (uint8_t i = 0; i < 16; i++) {
        uint16_t value = sbus_buffer[1 + 2 * i] + (sbus_buffer[2 + 2 * i] << 8);
        sbus_channels[i] = (value > PWM_MAX) ? PWM_MAX : (value < PWM_MIN) ? PWM_MIN : value;
      }
    }
  }
  HAL_UART_Receive_IT(&huart1, &sbus_buffer[buffer_index], 1);
}

int main(void) {
  HAL_Init();
  __HAL_RCC_GPIOC_CLK_ENABLE();
  __HAL_RCC_GPIOA_CLK_ENABLE();
  __HAL_RCC_USART1_CLK_ENABLE();

  GPIO_InitTypeDef GPIO_InitStruct = {0};
  GPIO_InitStruct.Pin = GPIO_PIN_13;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(GPIOC, &GPIO_InitStruct);

  GPIO_InitStruct.Pin = GPIO_PIN_8;
  GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
  GPIO_InitStruct.Pull = GPIO_PULLUP;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
  HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

  huart1.Instance = USART1;
  huart1.Init.BaudRate = 100000;
  huart1.Init.WordLength = UART_WORDLENGTH_8B;
  huart1.Init.StopBits = UART_STOPBITS_1;
  huart1.Init.Parity = UART_PARITY_NONE;
  huart1.Init.Mode = UART_MODE_RX;
  huart1.Init.HwFlowCtl = UART_HWCONTROL_NONE;
  huart1.Init.OverSampling = UART_OVERSAMPLING_16;
  HAL_UART_Init(&huart1);

  HAL_UART_Receive_IT(&huart1, sbus_buffer, 1);

  TIM_HandleTypeDef htim3;
  __HAL_RCC_TIM3_CLK_ENABLE();

  htim3.Instance = TIM3;
  htim3.Init.Prescaler = 71;
  htim3.Init.CounterMode = TIM_COUNTERMODE_UP;
  htim3.Init.Period = 19999;
  htim3.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
  HAL_TIM_PWM_Init(&htim3);

  TIM_OC_InitTypeDef sConfigOC = {0};
  sConfigOC.OCMode = TIM_OCMODE_PWM1;
  sConfigOC.Pulse = PWM_MID;
  sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
  sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;
  HAL_TIM_PWM_ConfigChannel(&htim3, &sConfigOC, TIM_CHANNEL_1);
  HAL_TIM_PWM_Start(&htim3, TIM_CHANNEL_1);

  while (1) {
    uint16_t throttle = sbus_channels[2];
    if (throttle > PWM_MAX) {
      throttle = PWM_MAX;
    } else if (throttle < PWM_MIN) {
      throttle = PWM_MIN;
    }
    __HAL_TIM_SET_COMPARE(&htim3, TIM_CHANNEL_1, throttle);
  }
}

这个代码示例中，我们使用了STM32的UART模块来接收来自遥控器的SBUS信号，并将其解析为PWM信号。然后，我们使用STM32的定时器模块来生成PWM信号，并通过L29N电机驱动模块将其输出到电机。在主循环中，我们不断地读取油门通道的PWM值，并将其输出到电机。注意，这个示例中只控制了一个电机，如果需要控制多个电机，需要使用更多的PWM输出通道。