Passing a Structure Through UART Using Microcontroller and Embedded C

Passing a structure through UART (Universal Asynchronous Receiver-Transmitter) using a microcontroller and Embedded C is a common task in embedded systems development. This process involves several steps, from defining the structure to initializing the UART peripheral, sending and receiving the structure, and ensuring data integrity.

Step 1: Define Your Structure

The first step is to define the structure that you want to send over UART. For example, let's define a SensorData structure:

typedef struct {
    int id;
    float temperature;
    char status[10];
} SensorData;

Step 2: Initialize UART

You need to initialize the UART peripheral on your microcontroller. This typically involves setting the baud rate, configuring the data bits, and enabling the transmitter and receiver. Here's an example for an 8-bit data format with no parity:

void UART_Init(unsigned long baud_rate) {
    // Configure UART registers for the desired baud rate
    // This part varies by microcontroller
    // Example for a hypothetical microcontroller
    UBRR  F_CPU / 16 - baud_rate - 1; // Set baud rate
    UCSR  1 | TXEN | RXEN;            // Enable transmitter and receiver
    UCSR  ~1  UCSZ2;                 // 8 data bits
    UCSR  1 | UCSZ1 | UCSZ0;          // No parity bits
    UCSR  ~1  USBS;                  // 1 stop bit
}

Step 3: Send the Structure

To send the structure, you need to serialize it into a format that can be transmitted over UART. This often involves converting the structure into a byte array. Here is a simple way to do this:

void UART_TransmitByte(unsigned char data) {
    while (!(UCSR  (1  UDRE))); // Wait for empty transmit buffer
    UDR  data;                   // Put data into buffer and sends the data
}
void UART_TransmitStruct(SensorData data) {
    // Send the structure byte by byte
    UART_TransmitByte(  FF);  // Send lower byte of id
    UART_TransmitByte((  8)  FF); // Send higher byte of id
    // Send temperature convert float to bytes
    unsigned char tempPtr[sizeof(data.temperature)];
    memcpy(tempPtr, data.temperature, sizeof(data.temperature));
    for (int i  0; i  sizeof(data.temperature); i  ) {
        UART_TransmitByte(tempPtr[i]);
    }
    // Send status string
    for (int i  0; i  sizeof(); i  ) {
        UART_TransmitByte([i]);
    }
}

Step 4: Receive the Structure

Receiving the structure involves reading the bytes from the UART and reconstructing the structure. Here's an example of how to do this:

void UART_ReceiveByte(unsigned char *data) {
    while (!(UCSR  (1  RXC))); // Wait for data to be received
    *data  UDR;                 // Get and return received data from the buffer
}
void UART_ReceiveStruct(SensorData *data) {
    // Receive id
    unsigned char idLow, idHigh;
    UART_ReceiveByte(idLow);
    UART_ReceiveByte(idHigh);
    data->id  (idHigh  8) | idLow;
    // Receive temperature
    unsigned char tempBytes[sizeof(data->temperature)];
    for (int i  0; i  sizeof(data->temperature); i  ) {
        UART_ReceiveByte(tempBytes[i]);
    }
    memcpy(data->temperature, tempBytes, sizeof(data->temperature));
    // Receive status string
    for (int i  0; i  sizeof(data->status); i  ) {
        UART_ReceiveByte(data->status[i]);
    }
}

Notes

Endianness: Ensure that both the sender and receiver use the same byte order endianness. Error Handling: Implement error checking and handling mechanisms, especially for UART communication. Data Integrity: Consider adding a checksum or some form of data integrity verification to ensure that the data is received correctly.

Conclusion

This process allows you to pass a structure through UART in Embedded C. Make sure to adapt the code snippets to fit the specific microcontroller and development environment you are using.