RS232 serial communication protocol tips

I used 232 of the communication protocols. I forgot to use Google every time I used them. Write an articleArticle, Record key issues of the 232 serial port protocol for later viewing.

 

Test TTL level:

1. The default high level;

2. the start position is low;

3. 8-Bit Data bit,Low front, high behind;

4. The stop bit is high.

 

 

Test RS232 level:

1.-5v---15v is 1, negative logic;

2. Convert the TTL to the 232 chip and convert the high level to the low level. Therefore, the 232 level displayed on the oscilloscope is the low level by default.

 

 

References:

1. Serial Interface: 232 485 and SPI: http://blog.ednchina.com/mancave/1986205/message.aspx