1
00:00:00,000 --> 00:00:02,500
电脑先发一帧查询。

2
00:00:02,500 --> 00:00:05,000
串口中断把字节收进来。

3
00:00:05,000 --> 00:00:07,500
主循环取出字节，拼成帧。

4
00:00:07,500 --> 00:00:10,000
先检查长度和 CRC。

5
00:00:10,000 --> 00:00:12,500
再核对类型、地址和命令。

6
00:00:12,500 --> 00:00:15,000
PB5 拉高发送，发完拉低接收。

7
00:00:15,000 --> 00:00:18,000
校验错就丢弃；参数错回错误状态。