MAX3232 USB to RS232 Serial Modules
The MAX3232 is an IC which converts between RS232 voltage levels (±12v or more) to logic levels.
It can be powered by a 5v supply for 5v logic, or 3.3v for 3.3v logic.
1. Small Board
These boards are quite small at around 1cm by 2cm and are useful for when space is limited or a connector other than DB-9 is being used.
Things to watch out for are that some boards do not have the RS232 and TTL sides marked, so probing with a multimeter is required to work out which pins are connected to which side, see the image below for pinout details. Also, as you can see in the picture, the TX and RX lines are only connected on one side so you’ll either need more multimeter probing or to solder the connecting wire to the top and bottom pads.
2. Large Board with DB-9 Connector
These boards are well marked and easy to use although the location of the pin header does limit the ways in which they can be connected to a mother board.
For information of the DB-9 connector click see this link here.3. MAX3232 Pinout
Note that the chip contains two TX drivers and two RX drivers, the second pair is usually used for CTS/RTS but these modules leave it unused.
- MAX3232 datasheet in HTML format.