Serialized Data Buffer

Code

#include <stdio.h>
#include <stdint.h>

void build_packet(uint8_t command, uint16_t value, uint8_t status, uint32_t checksum) {
    
    uint8_t buffer[10];

    // Your logic to fill buffer
    
    // Start byte = 0xA5 always:
    buffer[0] = 0xA5;

    // Command byte:
    buffer[1] = command;

    // Lower byte of value:
    buffer[2] = (value & 0xFF);

    // Upper byte of value:
    buffer[3] = (value & 0xFF00) >> 8;

    // Status byte:
    buffer[4] = status;

    // Lowest byte of checksum:
    buffer[5] = (checksum & 0xFF);

    // 2nd to lowest byte of checksum:
    buffer[6] = (checksum & 0xFF00) >> 8;

    // 2nd to highest byte of checksum:
    buffer[7] = (checksum & 0xFF0000) >> 16;

    // Highest byte of checksum:
    buffer[8] = (checksum & 0xFF000000) >> 24;

    // End byte = 0x5A always:
    buffer[9] = 0x5A;

    // Then print buffer
    for(int i = 0; i < 10; i++){
        printf("%d ", buffer[i]);
    }
}

int main() {
    uint8_t cmd, status;
    uint16_t val;
    uint32_t crc;

    scanf("%hhu %hu %hhu %u", &cmd, &val, &status, &crc);
    build_packet(cmd, val, status, crc);
    return 0;
}

Solving Approach