DTU 数据接收前导字校验代码解析

This code is used for receiving data from a DTU (Data Transfer Unit) through a UART communication interface. The code first reads the received data from the UCA1RXBUF register and stores it in the DTU_Rx_Data variable.

The code then checks if the DTU_Pre_Received flag is set to 0, which indicates that the pre-amble bytes (0x55FDAA) have not been received yet. If the flag is set to 0, the code checks if the received data matches the first pre-amble byte (0x55). If it does, the DTU_Pre_Num counter is incremented by 1.

If the received data does not match the first pre-amble byte, or if DTU_Pre_Num is not equal to 0, the code checks if DTU_Pre_Num is equal to 1 and the received data matches the second pre-amble byte (0xFD). If it does, DTU_Pre_Num is incremented by 1.

If DTU_Pre_Num is equal to 2 and the received data matches the third pre-amble byte (0xAA), the pre-amble bytes have been successfully received, and the DTU_Pre_Received flag is set to 1. The DTU_Rx_Data_Count variable is also reset to 0, indicating that the data reception process has started.

If the received data does not match any of the pre-amble bytes, the code resets the DTU_Pre_Num and DTU_Pre_Received variables to 0 and returns, indicating that the pre-amble bytes were not received successfully.