This fun project receives text messages (sms) and prints them via the thermal printer. Additionally, the number of received messages is displayed on the front. (I was a bit optimistic using an 8 digit display 😀 )

Materials Needed

  • an arduino nano board
  • an rs232 thermal printer
  • an sim800l gsm module
  • an 7 segment modul MAX7219
  • an MAX232 IC with passives
  • punch of transistors to build voltage dividers
  • different voltage regulators (9V, 5V, 3.8-4.2V) and 3D printer - of course :D


The case consists of a single block in which all the electronics can be placed it. The thermal printer nicely covers the housing and holds the 7-segment display module in place.

I’ve drawn a diagram for the wiring which can be found on GitHub:
Please consider the different voltage levels!! A 5 volts supply will blow up the sim800 module!

The software is in progress and can be found on GitHub.