Sitinut Waisara maxmacstn

Controlling the Brother P-Touch Cube label maker from a computer

The Brother PTP300BT label maker is intended to be controlled using the official Brother P-Touch Design & Print iOS/Android app. The app has arbitrary limits on what you can print (1 text object and up to 3 preset icons), so I thought it would be a fun challenge to reverse engineer the protocol to print whatever I wanted.

Python code at the bottom if you want to skip the fine details.

Process

Intitially I had a quick peek at the Android APK to see if there was any useful information inside. The code that handles the communication with the printer in Print&Design turned out to be a native library, but the app clearly prepares a bitmap image and passes it to this native library for printing. Bitmaps are definitely something we can work with.

Printing to a Brother P-Touch Cube PT-P300BT label printer from a computer

Superseded document

This Gist is superseded by https://github.com/Ircama/PT-P300BT

Introduction

The Brother P-touch Cube PT-P300BT labelling machine is intended to be controlled from the official Brother P-touch Design&Print 2 app for Android and iOS devices, instead of from a computer.

Create Root Certificate Authority and self-signed certificate for your Home Assistant. Compatible with Chrome browser > version 58, including the macOS Catalina 10.15 / iOS 13 (and above) new requirements.

Create Root Key

Attention: this is the key used to sign the certificate requests, anyone holding this can sign certificates on your behalf. So keep it in a safe place!

openssl genrsa -des3 -out rootCA.key 4096

Controlling the Brother P-Touch Cube label maker from a computer

The Brother PTP300BT label maker is intended to be controlled using the official Brother P-Touch Design & Print iOS/Android app. The app has arbitrary limits on what you can print (1 text object and up to 3 preset icons), so I thought it would be a fun challenge to reverse engineer the protocol to print whatever I wanted.

Python code at the bottom if you want to skip the fine details.

Process

Intitially I had a quick peek at the Android APK to see if there was any useful information inside. The code that handles the communication with the printer in Print&Design turned out to be a native library, but the app clearly prepares a bitmap image and passes it to this native library for printing. Bitmaps are definitely something we can work with.

	// First, go to https://shopee.co.th/user/purchase, and open DevTools.

	// Step 1 - Run this code to scroll all the way to the bottom.
	const timer = setInterval(() => scrollTo(0, 10000000), 800)

	setTimeout(() => {
	// Step 2 - Stop scrolling after 1 minute.
	clearInterval(timer)

	// Step 3 - Sum the total purchase price!