Serial debugger circuit implemented with several discrete components

The typical RS-232 serial port signal swings between positive and negative levels. When sending data, the sending end driver outputs positive levels between +5V and +15V, and negative levels between -5V and -15V. However, the microcontroller serial port Generally it is TTL level (0V~5V). Two serial ports cannot simply be connected directly with wires.

It uses VD2 and C1 to obtain the negative power required for communication from the RS-232 interface, and can well achieve level conversion and data communication between the two interfaces. The author's years of use have proven that the communication effect is very good, and, in When the operating voltage is 3.3V, it is still very stable.

If the circuit in the picture is made into a small circuit board, it can be installed into an RS-232 socket, and VCC, TXD, RXD, and GND can be connected with four-core cables to create a universal serial data communication line.