Some simple tools for working with TRMNL

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README.md

This project is work in progress.

A mashup of re-purposed Kobo ereaders, a BlueTooth thermal receipt printer and a Raspberry Pi Zero W. Combine them into a system for displaying Markdown task lists, with items appearing on different devices/formats depending on their level of importance!

Aims

On my local network I have several devices which I want to display my current todo lists.

A Raspberry Pi Zero W

Although it's low power (sub 1W) it can run full ARMv6 Linux distros. I have a minimal Alpine Linux installation and just access the Pi over SSH.

It's pretty low spec but it can run what I want, including:

Compiling Go programs
Converting Markdown to images via various packages and scripts
Running Python

It's slow at some of those things but usable for my needs.

X6 Thermal Printer

A super-cheap generic thermal receipt printer from AliExpress. My model reports itself as X6H but online sources usually just refer to X6 printers.

It cost 6ドル.60 including a roll of paper. At that price I had to buy one just to experiment with. Refill rolls can be bought for 30p-70p depending on how many you buy at once.

The quality is better than I expected and it's pretty fast, small and quiet. Loads of fun.

A drawback is that it doesn't work with standard drivers but instead depends on an Android app called Tiny Print (or something similar for iDevices). Tiny Print is fine for intended uses of a cheap fun printer like this but it's annoying to only be able to print via a phone/tablet and the app has limited options. It doesn't feel like a high quality piece of software.

I started to look into sending prints directly over BlueTooth but when it got to reverse-engineering the protocol I realised I'd opened a big can of worms. I tried some more searching and eventually found TiMini-Print which is a really nice alternative to Tiny Print. It works with a lot of these kinds of printers, including mine.

Importantly for this project, TiMini-Print allows prints to be sent via the command line, meaning it can be controlled with shell scripts.

The printer can only be connected via BlueTooth. So the Pi sits in the middle. Other devices on the network talk to the Pi, the Pi sends the prints to the printer.

Some old Kobo E-Ink Readers

I have 2 Kobo Glos and a Kobo Mini. I do use them for reading, but most of the time they sit unused. I want to be able to use them as displays.

Simplified software for working with TRMNL. I didn't need all of the features of TRMNL Server myself so have just built a small version to suit my needs.