Linux串口断帧处理

报文格式

1 Byte	4 Byte	N Byte	4 Byte	1 Byte
0x02	报文长度	报文	CRC16	0x03

1. 每条报文以 STX（0x02）起始符开始，以 ETX（0x03）终止符结束。

2. 报文正文长度采用 4 字节的 10 进制字符串标识，如报文正文长度为十

进制 298，则相应的字段为"0298"。

3. 报文正文采用 json 字符串形式进行描述。

4. 报文正文后跟报文正文的 CRC16 校验码，CRC16 校验码采用 4 字节的

16 进制字符串标识，如 CRC16 校验码为 0x89 0xA9，则相应的字段为为"89A9"。

5. 串口数据采用 CRC16（XMODEM）算法校验，举例：校验报文原文"abcdefg"，

CRC16 结果为 0x7658。

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdbool.h>
#include <unistd.h>
#include <fcntl.h>
#include <termios.h>#define START_BYTE 0x02
#define END_BYTE 0x03static int times = 0;
int my_read(uint8_t *data, uint32_t max_len)
{char *a="\x02\x30\x30\x37\x37\x7B\x22\x64\x61\x74\x61\x22\x3A\x7B\x22\x61";char *b="\x63\x74\x69\x6F\x6E\x22\x3A\x31\x7D\x2C\x22\x63\x6D\x64\x22\x3A\x22\x43\x32\x22\x2C\x22\x74\x69\x6D\x65\x22\x3A\x22\x31\x36\x39\x37\x31\x31\x30\x36\x39\x39\x30\x38\x33\x22\x2C\x22\x6D\x73\x67\x5F\x69\x64\x22\x3A\x22\x31\x36\x39\x37\x31\x31\x30\x36\x39\x39\x22";char *c="\x7D\x44\x42\x46\x32\x03";size_t bytesRead = 0;if(times==0){bytesRead = 16;memcpy(data, a, 16);times++;}else if(times==1){bytesRead = 65;memcpy(data, b, bytesRead);times++;}else{times = 0;bytesRead = 6;memcpy(data, c, bytesRead);}return bytesRead;}int my_recv(uint8_t *recv_data, uint32_t *recv_len)
{// 从串口接收数据uint8_t buffer[1024] = {0};*recv_len = 0;size_t bytesRead = 0;while (true) {bytesRead = my_read(buffer, sizeof(buffer));// 处理接收到的数据if (bytesRead <= 0) {break;}printf("bytesRead=%ld\n",bytesRead);if(buffer[0] == START_BYTE){*recv_len = bytesRead;memcpy(recv_data, buffer, bytesRead);}else{if((*recv_len+bytesRead)> sizeof(buffer)){*recv_len = 0;break;}memcpy(recv_data+*recv_len, buffer, bytesRead);*recv_len += bytesRead;}if(recv_data[0] != START_BYTE) {*recv_len = 0;break;}if(recv_data[*recv_len-1] == END_BYTE){return *recv_len;}} return -1;
}int main() {uint8_t frame[1024];int frame_len;memset(frame, 0, sizeof(frame));printf("len=%d\n", my_recv(frame, &frame_len));if(frame_len > 6){// 打印报文数据printf("Received frame: ");for (size_t i = 0; i < frame_len-10; i++) {printf("%02x ", frame[i+5]);}printf("\n");}return 0;
}