Custom LCD Controller for Printrbot Simple (Metal)

In order to print with the Printrbot Simple Metal you have to connect your computer with your printer via USB and make sure that the computer continuously sends data to the printer. If your computer crashes, your printer stops and your maybe long hour print is a piece of chunk. If your computer goes into stand by the result is the same. And there are various other reasons like energy consumption. The way to go is untethered printing.

The Printrbot Simple Metal is capable of that in two ways, both of them require a Mini-SD card inserted into the printer. The first way is to write the G-Codes generated by your Slicer, typically Repetier Host and Slicr to the SD-Card. Name it auto0.gcode, insert the card into the printer. Shut it down and on again. The printer should now start to print. But you will not know if it works for a couple of minutes as it’s first heating up. Nothing moves, etc. I tried that a couple of times and found the procedure to be very annoying.

The second method is using the Addon LCD Controller sold by Printrbot.

Getting your hands on a LCD Controller

Your Printrbot is already capable of displaying a nice LCD-Menu with all kinds of options and the option to browse the SD-card and run any print from it untethered from your PC. All that is needed is a Standard 20×4 LCD Display and a rotary encoder. A rotary encoder is a special kind of input sensor that sends signals when it is rotated.

Printrbot sells these LCDs for $65 in their store. But they still have that wood look. It does not match the Metals Design. And, as I am living in Germany you will have to wait a few days for it to arrive and you will likely have some issues regarding customs. I did not found a german distributor a few weeks ago so I wanted to built my own. A few days ago I have found 3ddinge.de selling the LCD Controller in Germany for €70. That’s a lot of money and by doing it yourself you will end up with 30-40 Euros for the LCD Controller.

Do it yourself

As said before the Printrbot has everything built in. There is an expansion slot (Exp2) with 14 pins that allows for connecting the PCB that hosts the LCD Display and the rotary encoder. I have found an excellent resource: Ricks Blog. Rick explains the pinout of the Expension slot and has created his own PCB. Instead of building my own PCB, I just used Ricks PCB Layout he provides and sent them to Smart Prototyping for manufacturing. I received the PCBs 3 weeks later. In the meantime I ordered the BOM. Rick provides everything in his blog but just a quick tip to resistor R1 which will depend on the LCD display you want to use: Adafruit has a very detailed explanation of how to calculate the correct value for the Resistor: Adafruits 20×4 LCD Character Tutorial.

Step by Step

1. Get Ricks PCB (or build your own based on his schematics). Rick has published the gerber files free of charge. I have a few PCBs left. If you are interested I will send you a PCB if you are willing to pay the shipping costs (about $4-$10 depends on where you live).
2. Find a nice LCD 20×4 HD44780 Display. There are a lot of different colors available. Adafruit sells them for example. I opted for a nice White on Blue Display.
3. Determine the correct Resistor value for R1. If you don’t know how to do it: Adafruits 20×4 LCD Character Tutorial will be very helpful.
4. Find a nice rotary encoder. I desoldered a rotary encoder from an old PCB and it worked flawlessly.
5. You will also need a 14 pin cable. You will get that very cheap at ebay or create one yourself.
6. If you don’t have the other materials at hand order them at Digikey, Mouser, Conrad, Reichelt…
7. Rick shows the assembled PCB on his website, and reading the schematics should give you enough hints to assemble your own PCB.
8. Make sure you connect the cable correctly. Pin 1 is GND, Pin 2 is +5V. I think Pin 1 is marked on the Printrboard with a small dot, but use your Multimeter if you are not sure. It also depends on the Printrboard (there are different Revisions) you have.
9. Turn on your Printrbot and have fun :-).

If you have any questions or want to “order” a PCB, just leave a message.

Enclosure

Rick also has created a Housing for this controller which looks awesome in my opinion. You can print it directly on your Printrbot.