I like using PinePhone as a general purpose computer for various tasks and purposes, such as a dedicated alarm clock, trying out networking software (I have several of them), etc. This time I tried attaching a POS Printer, creating a print server.
Linux is great when it comes to printers support, thanks to CUPS. It usually just works. For the POS Printer I needed to install additional drivers, but luckily there are some generic ones available, covering most of the 58mm / 80mm thermal printers (they share the same ESC/POS protocol, making them widely compatible).
Initially I wanted to use the official vendor-supplied printer drivers for Linux ARM, but there are several ARM architectures and this wasn’t the right one. Therefore I used these CUPS drivers instead: github.com/klirichek/zj-58. And since this is open source, I was able to compile them for the PinePhone’s ARM architecture and get it working.
Adding a printer can be done through the CUPS web interface running on localhost:631, where you can add the printer connected over USB. You can also connect a printer over serial or Bluetooth, all you need is a special connection URL: serial:/dev/ttyXXX or bluetooth://123456789a/ where you specify the serial file or the device address.
Once the printer is added, you can use all the lp* commands to manage your print jobs, such as lpoptions to configure the printer defaults, or lp tux.png to print out an image on a thermal printer!