Troubleshooting

Nothing seems to be working!

First open the front flap and check for any LED power indicator on the Arduino board. If there's no light, the power supply might not be plugged in, or there may be an electrical short in your wiring. Reverse the assembly steps to open the box and check all your wiring.

The green status light comes on but Tweets are never printed

Connect a USB cable and use the Serial Monitor in the Arduino IDE (set the line speed to 57600 baud). The sketch will show its current status at each stage of its operation. Most likely, the network settings will need to be edited.

It might also be a simple paper issue. Open the printer top latch and confirm that thermal paper is loaded and properly fed out the top.

If you turn on green button while holding down the little black button next to the printer's green LED it will do a small print test, that can help determine if you're having printing issues as well.

Help! My printer just prints gibberish!

Hold down the small black button on top of the printer while turning it on. A test page should print showing the font table and some diagnostic information. Look for the line that reads 'BAUDRATE':

Most printers arrive from the factory set for 19200 baud, but a few may be set to 9600. This will not negatively impact the performance of your unit! The speed of the paper through the printer is already much less than this and you will not see any difference…it's strictly a data protocol issue of getting the microcontroller and printer communicating. So, if you do have a 9600 baud printer, you'll need to edit the library fileAdafruit_Thermal.cpp, changing this line:
Download: file
_printer->begin(19200);
to this:
Download: file
_printer->begin(9600);
Recompile and upload the sketch to the Arduino board, and the output should now be legible.
This guide was first published on Jul 29, 2012. It was last updated on Jul 29, 2012. This page (Troubleshooting) was last updated on May 04, 2015.