在stm32上搭建rs485modbus通信hal库源码

以下是在STM32上搭建RS485 Modbus通信HAL库源码的步骤：

配置GPIO口

首先，需要配置GPIO口，将其设置为Modbus的通信口。具体来说，需要将TXD（发送）与RXD（接收）引脚设置为开漏输出，同时使DE（驱动使能）引脚输出高电平，RE（接收使能）引脚输出低电平。以下是示例代码：

/* Enable GPIO clock */
__HAL_RCC_GPIOA_CLK_ENABLE();

/* Configure USART3 TX (PA.10) and RX (PA.11) as alternate function push-pull */
GPIO_InitStruct.Pin = GPIO_PIN_10 | GPIO_PIN_11;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
GPIO_InitStruct.Alternate = GPIO_AF7_USART3;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

/* Configure DE (PB.13) and RE (PB.14) as output push-pull */
GPIO_InitStruct.Pin = GPIO_PIN_13 | GPIO_PIN_14;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);

/* Set DE high and RE low */
HAL_GPIO_WritePin(GPIOB, GPIO_PIN_13, GPIO_PIN_SET);
HAL_GPIO_WritePin(GPIOB, GPIO_PIN_14, GPIO_PIN_RESET);

配置USART串口

接下来，需要配置USART串口，使其支持Modbus通信。具体来说，需要设置串口的波特率、数据位、停止位、奇偶校验位、流控制等参数。以下是示例代码：

/* Enable USART clock */
__HAL_RCC_USART3_CLK_ENABLE();

/* Configure USART3 */
huart.Instance = USART3;
huart.Init.BaudRate = 9600;
huart.Init.WordLength = UART_WORDLENGTH_8B;
huart.Init.StopBits = UART_STOPBITS_1;
huart.Init.Parity = UART_PARITY_NONE;
huart.Init.Mode = UART_MODE_TX_RX;
huart.Init.HwFlowCtl = UART_HWCONTROL_NONE;
huart.Init.OverSampling = UART_OVERSAMPLING_16;
HAL_UART_Init(&huart);

配置DMA传输

为了提高通信效率，可以使用DMA传输机制。具体来说，需要配置DMA传输的通道、传输方向、传输数据长度等参数。以下是示例代码：

/* Enable DMA clock */
__HAL_RCC_DMA1_CLK_ENABLE();

/* Configure DMA channel */
hdma_usart3_rx.Instance = DMA1_Stream1;
hdma_usart3_rx.Init.Channel = DMA_CHANNEL_4;
hdma_usart3_rx.Init.Direction = DMA_PERIPH_TO_MEMORY;
hdma_usart3_rx.Init.PeriphInc = DMA_PINC_DISABLE;
hdma_usart3_rx.Init.MemInc = DMA_MINC_ENABLE;
hdma_usart3_rx.Init.PeriphDataAlignment = DMA_PDATAALIGN_BYTE;
hdma_usart3_rx.Init.MemDataAlignment = DMA_MDATAALIGN_BYTE;
hdma_usart3_rx.Init.Mode = DMA_CIRCULAR;
hdma_usart3_rx.Init.Priority = DMA_PRIORITY_HIGH;
hdma_usart3_rx.Init.FIFOMode = DMA_FIFOMODE_DISABLE;
HAL_DMA_Init(&hdma_usart3_rx);

/* Associate the DMA handle with the USART RX DMA request */
__HAL_LINKDMA(&huart, hdmarx, hdma_usart3_rx);

/* Enable DMA transfer complete interrupt */
__HAL_DMA_ENABLE_IT(&hdma_usart3_rx, DMA_IT_TC);

编写Modbus通信函数

最后，需要编写Modbus通信函数，实现Modbus协议的各种操作，例如读取/写入寄存器、读取/写入线圈等。以下是示例代码：

/* Modbus function code definitions */
#define MB_FC_READ_COILS            0x01
#define MB_FC_READ_DISCRETE_INPUTS  0x02
#define MB_FC_READ_HOLDING_REGS     0x03
#define MB_FC_READ_INPUT_REGS       0x04
#define MB_FC_WRITE_SINGLE_COIL     0x05
#define MB_FC_WRITE_SINGLE_REG      0x06
#define MB_FC_WRITE_MULTIPLE_COILS  0x0F
#define MB_FC_WRITE_MULTIPLE_REGS   0x10

/* Modbus exception code definitions */
#define MB_EX_ILLEGAL_FUNCTION      0x01
#define MB_EX_ILLEGAL_DATA_ADDRESS  0x02
#define MB_EX_ILLEGAL_DATA_VALUE    0x03
#define MB_EX_SLAVE_DEVICE_FAILURE  0x04
#define MB_EX_ACKNOWLEDGE           0x05
#define MB_EX_SLAVE_DEVICE_BUSY     0x06
#define MB_EX_MEMORY_PARITY_ERROR   0x08
#define MB_EX_GATEWAY_PATH_FAILED   0x0A
#define MB_EX_GATEWAY_TARGET_FAILED 0x0B

/* Modbus error frame size */
#define MB_ERROR_FRAME_SIZE         5

/* Modbus read coils function */
uint8_t MB_Read_Coils(uint8_t slave_address, uint16_t start_address, uint16_t quantity, uint8_t *data)
{
    uint8_t buf[256];
    uint16_t len = 0;

    /* Build Modbus request frame */
    buf[len++] = slave_address;
    buf[len++] = MB_FC_READ_COILS;
    buf[len++] = start_address >> 8;
    buf[len++] = start_address & 0xFF;
    buf[len++] = quantity >> 8;
    buf[len++] = quantity & 0xFF;

    /* Send Modbus request frame */
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_13, GPIO_PIN_SET);
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_14, GPIO_PIN_RESET);
    HAL_UART_Transmit(&huart, buf, len, 100);
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_13, GPIO_PIN_RESET);
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_14, GPIO_PIN_SET);

    /* Receive Modbus response frame */
    HAL_UART_Receive_DMA(&huart, buf, 256);
    while (HAL_DMA_GetState(&hdma_usart3_rx) != HAL_DMA_STATE_READY);
    len = 256 - __HAL_DMA_GET_COUNTER(&hdma_usart3_rx);

    /* Check Modbus response frame */
    if (len == MB_ERROR_FRAME_SIZE)
    {
        /* Modbus exception occurred */
        return buf[2];
    }
    else if (len == 3 + (quantity + 7) / 8)
    {
        /* Modbus response received */
        memcpy(data, buf + 3, (quantity + 7) / 8);
        return 0;
    }
    else
    {
        /* Modbus response frame length error */
        return MB_EX_SLAVE_DEVICE_FAILURE;
    }
}

以上是在STM32上搭建RS485 Modbus通信HAL库源码的步骤和示例代码。需要注意的是，这只是一个简单的示例，实际应用中还需要根据具体情况进行修改和优化