2_How to read the UART notes of the protocol interface of the schematic diagram
The two parties of the communication first agree on the communication rate, such as the baud rate of 115200
When idle, the 2440 side maintains a high level
1> When starting to send, the high level is pulled down by 2440 and lasts for a time of T, T=1/baud rate;
2> At this time, the receiving PC can know that the 2440 is going to start sending data, and be ready
3~> 2440 starts to send character A (0x41, 01000001), and sends 8bit data respectively. After sending, the level is pulled high, that is, the stop bit.
Start bit: high level pull low
High level: maintain high level
When connecting the serial port on the computer, the following parameters need to be agreed (Speed=baud rate; Data=8 means the data is 8bit; Stopb