STM32F103ZE怎么按下按键后，通过485串口发送数据？请写出最详细示例代码

好的，这里是一个简单的示例代码，可以通过按下按键后，通过485串口发送数据：

#include "stm32f10x.h"
#include "stm32f10x_gpio.h"
#include "stm32f10x_usart.h"

#define USART1_TX_PIN GPIO_Pin_9
#define USART1_RX_PIN GPIO_Pin_10
#define USART1_PORT GPIOA

#define USART2_TX_PIN GPIO_Pin_2
#define USART2_RX_PIN GPIO_Pin_3
#define USART2_PORT GPIOA

#define RS485_DIR_PIN GPIO_Pin_8
#define RS485_DIR_PORT GPIOB

void USART1_Init(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    USART_InitTypeDef USART_InitStructure;

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1 | RCC_APB2Periph_GPIOA, ENABLE);

    // Configure USART1 Tx (PA9) as alternate function push-pull
    GPIO_InitStructure.GPIO_Pin = USART1_TX_PIN;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(USART1_PORT, &GPIO_InitStructure);

    // Configure USART1 Rx (PA10) as input floating
    GPIO_InitStructure.GPIO_Pin = USART1_RX_PIN;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    GPIO_Init(USART1_PORT, &GPIO_InitStructure);

    USART_InitStructure.USART_BaudRate = 9600;
    USART_InitStructure.USART_WordLength = USART_WordLength_8b;
    USART_InitStructure.USART_StopBits = USART_StopBits_1;
    USART_InitStructure.USART_Parity = USART_Parity_No;
    USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
    USART_Init(USART1, &USART_InitStructure);

    USART_Cmd(USART1, ENABLE);
}

void USART2_Init(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    USART_InitTypeDef USART_InitStructure;

    RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);

    // Configure USART2 Tx (PA2) as alternate function push-pull
    GPIO_InitStructure.GPIO_Pin = USART2_TX_PIN;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(USART2_PORT, &GPIO_InitStructure);

    // Configure USART2 Rx (PA3) as input floating
    GPIO_InitStructure.GPIO_Pin = USART2_RX_PIN;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    GPIO_Init(USART2_PORT, &GPIO_InitStructure);

    USART_InitStructure.USART_BaudRate = 9600;
    USART_InitStructure.USART_WordLength = USART_WordLength_8b;
    USART_InitStructure.USART_StopBits = USART_StopBits_1;
    USART_InitStructure.USART_Parity = USART_Parity_No;
    USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
    USART_Init(USART2, &USART_InitStructure);

    USART_Cmd(USART2, ENABLE);
}

void RS485_Init(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);

    // Configure RS485 direction control pin (PB8) as output push-pull
    GPIO_InitStructure.GPIO_Pin = RS485_DIR_PIN;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(RS485_DIR_PORT, &GPIO_InitStructure);

    // Set RS485 direction to receive mode
    GPIO_SetBits(RS485_DIR_PORT, RS485_DIR_PIN);
}

void RS485_SendData(uint8_t *data, uint16_t len)
{
    // Set RS485 direction to transmit mode
    GPIO_ResetBits(RS485_DIR_PORT, RS485_DIR_PIN);

    // Send data
    for (uint16_t i = 0; i < len; i++)
    {
        while (USART_GetFlagStatus(USART2, USART_FLAG_TXE) == RESET);
        USART_SendData(USART2, data[i]);
    }

    // Wait for transmission to complete
    while (USART_GetFlagStatus(USART2, USART_FLAG_TC) == RESET);

    // Set RS485 direction to receive mode
    GPIO_SetBits(RS485_DIR_PORT, RS485_DIR_PIN);
}

int main(void)
{
    // Initialize USART1 for receiving data
    USART1_Init();

    // Initialize USART2 for transmitting data
    USART2_Init();

    // Initialize RS485 direction control pin
    RS485_Init();

    while (1)
    {
        if (GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_0) == RESET)
        {
            // Button is pressed, send data over RS485
            uint8_t data[] = {0x01, 0x02, 0x03};
            RS485_SendData(data, sizeof(data));
        }
    }
}

在这个示例代码中，我们首先初始化了USART1和USART2，用于接收数据和发送数据。然后，我们初始化了RS485方向控制引脚，用于控制数据的发送和接收方向。最后，在主循环中，我们检测按键是否按下，并在按下时发送一些数据。