Tag Archives: DB9

RS232 Communication – The Level Conversion

Hello and welcome back. Continuing our discussion on RS232 serial communication in this part we will make a RS232 level converter. In the last tutorial we saw that how RS232 level signals differs from normal logic signals. So to interface RS232 level signals to our MCUs we need a "Level converter". And in this tutorial we will make one. What a level converter will do is to convert RS232 level signals (HIGH=-12V LOW=+12V) from PC to TTL level signal (HIGH=+5V LOW=0V) to be fed to MCU and also the opposite. Fig – Working of RS232 level converter       As RS232 is such a common protocol there is a dedicated IC designed for this purpose of "Level Conversion". This IC is MAX232 from Maxim. By using charge pumps it generates high voltages(12V) and negative voltages(-12V). Now lets make it! Things you need S.No Item Value Qty 1 MAX232 IC 1 2 Capacitors 1uF 4 3 10uF 1 4 DB9 Female Connector 1 5 General Purpose PCB 1 6 Some Wires – –   Fig – Stuffs required for RS232 level converter.     Now having all the stuffs in our working table lets begin. The Schematic Fig – Schematic for RS232 level converter.     Assembly Assemble the circuit according to the schematic on a small piece of general […]