STM32l431RC使用串口实现第一个按钮发生hello，第二个按键Led翻转

好的，你可以按照以下步骤实现：

1. 首先需要配置串口和GPIO外设。具体可以参考ST官方提供的例程，或者使用CubeMX进行配置。

2. 在main函数中初始化串口和GPIO，并开启中断。

3. 在main函数中使用while循环监听按键状态，并根据按键状态执行相应的操作。可以使用HAL库提供的函数来读取GPIO状态。

4. 当第一个按键被按下时，向串口发送"hello"字符串。可以使用HAL库提供的函数来发送数据。

5. 当第二个按键被按下时，翻转LED状态。可以使用HAL库提供的函数来设置GPIO输出状态。

下面是一个参考代码，供你参考：

#include "main.h"
#include "stdio.h"
#include "string.h"

UART_HandleTypeDef huart1;
GPIO_TypeDef* LED_GPIO_Port = GPIOA;
uint16_t LED_Pin = GPIO_PIN_5;
GPIO_TypeDef* BUTTON_GPIO_Port = GPIOC;
uint16_t BUTTON1_Pin = GPIO_PIN_13;
uint16_t BUTTON2_Pin = GPIO_PIN_14;

void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_USART1_UART_Init(void);

int main(void)
{
  HAL_Init();
  SystemClock_Config();
  MX_GPIO_Init();
  MX_USART1_UART_Init();

  uint8_t button1_state = 0;
  uint8_t button2_state = 0;
  uint8_t last_button1_state = 0;
  uint8_t last_button2_state = 0;

  while (1)
  {
    button1_state = HAL_GPIO_ReadPin(BUTTON_GPIO_Port, BUTTON1_Pin);
    button2_state = HAL_GPIO_ReadPin(BUTTON_GPIO_Port, BUTTON2_Pin);

    if (button1_state == GPIO_PIN_RESET && last_button1_state == GPIO_PIN_SET)
    {
      char* str = "hello\r\n";
      HAL_UART_Transmit(&huart1, (uint8_t*)str, strlen(str), 100);
    }

    if (button2_state == GPIO_PIN_RESET && last_button2_state == GPIO_PIN_SET)
    {
      HAL_GPIO_TogglePin(LED_GPIO_Port, LED_Pin);
    }

    last_button1_state = button1_state;
    last_button2_state = button2_state;
  }
}

void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }

  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
  {
    Error_Handler();
  }
}

static void MX_USART1_UART_Init(void)
{
  huart1.Instance = USART1;
  huart1.Init.BaudRate = 115200;
  huart1.Init.WordLength = UART_WORDLENGTH_8B;
  huart1.Init.StopBits = UART_STOPBITS_1;
  huart1.Init.Parity = UART_PARITY_NONE;
  huart1.Init.Mode = UART_MODE_TX_RX;
  huart1.Init.HwFlowCtl = UART_HWCONTROL_NONE;
  huart1.Init.OverSampling = UART_OVERSAMPLING_16;
  huart1.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
  huart1.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
  if (HAL_UART_Init(&huart1) != HAL_OK)
  {
    Error_Handler();
  }
}

static void MX_GPIO_Init(void)
{
  GPIO_InitTypeDef GPIO_InitStruct = {0};

  __HAL_RCC_GPIOA_CLK_ENABLE();
  __HAL_RCC_GPIOC_CLK_ENABLE();

  HAL_GPIO_WritePin(LED_GPIO_Port, LED_Pin, GPIO_PIN_RESET);

  GPIO_InitStruct.Pin = LED_Pin;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(LED_GPIO_Port, &GPIO_InitStruct);

  GPIO_InitStruct.Pin = BUTTON1_Pin|BUTTON2_Pin;
  GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
  GPIO_InitStruct.Pull = GPIO_PULLUP;
  HAL_GPIO_Init(BUTTON_GPIO_Port, &GPIO_InitStruct);
}

注意：此代码只是一个简单的参考，实际应用中需要根据具体需求进行修改和优化。同时，需要注意硬件电路的连接是否正确。