libwally for Arduino and Mbed

About this library

libwally is an bitcoin library developed and maintained by Blockstream. It is used in many projects like Green Wallet, C-Lightning and others, so it's really well maintained and tested in real projects.

This repository introduces a few hacks for Arduino and Mbed build systems that allows you to use the library out of the box.

As you see libwally-core is included as a submodule, and the src folder only contains aliases to the original files of the library. These files are generated by build.py script. It results in a huge mess in src/ folder, but it works!

Tested on ESP32 (M5Stack, TTGO) and STM32F469I-Discovery (Mbed OS - bare metal, no RTOS).

Installation

For Arduino:

Clone this repo with --recursive flag to the Arduino/libraries/ folder (or download zip file and select Sketch->Include Library->Add .ZIP Library. Check out the example to see it in action.

Make sure you have secp256k1 library installed. In your sketch add #include <secp256k1> even if you are not using - this will force Arduino IDE to copy secp256k1 library to the build folder as well.

For Mbed:

[DOESNT WORK YET]

Clone this repo with --recursive flag to the project folder, or whatever folder you store libraries in. In the online IDE do Import Library and put there a link to this repository.

Check out the example. You can also import this project and start from there.

Important! Library mostly uses stack, and mbed has pretty small default limitat for the stack size. You can increase the stack size in mbed_app.json file:

{
    "target_overrides": {
        "*": {
            "rtos.main-thread-stack-size": "8192"
        }
    }
}

Or you can use bare-metal mbed version:

{
	"requires": ["bare-metal"]
}

Usage

A very basic example: