Serial Port Mini RS232 to TTL Converter Adaptor Module Board MAX3232 with Arduino

So I buy 5 of these little things when I find out I am dealing with RS232 device instead of a TTL device.  They arrive quick and I am delighted only to find I dont quite know how to wire them up.  The project is to use an Arduino – which I love dearly – to drive an LED rolling display. I am not an electronics expert – so I struggled a little and popped 2 of them good and proper..

Never mind.  I’ll buy this instead

I am as always standing on the shoulders of giants –


So my experience is:

From the RS232 Port – RX, TX and GND.  Thats the -> -<and the – signs.  Easy enough


-> RX

<- TX

On the TTL (Arduino)  side – DO NOT USE 5V use 3.3V as this toasts the device and heats up and like tops itself.  It certainly got very toasty when I put 5V across it.  This could be because I messed up somewhere in the wiring but it certainly works well for me.  I can also use the SoftwareSerial library as well so I don’t need to use TX/RX on the TTL Serial pins 0 and 1

So TTL is


-> – PIN X

<- PIN Y

For my device I used PIN 0 and PIN 1 – TX/RX – but I guess you can use other pins.

TTL RS232 Pinouts

TTL RS232 Pinouts



Hope this helps – it does work!