Instructions for setting up the Arduino IDE to compile the firmware:

[TrystanLea]

A note for folk wondering what this new documentation site is, from the emonTx4 thread:

@TrystanLea

We are in the process of moving from the old guide documentation to a new site based on ‘Read the docs’. Please see: https://openenergymonitor.org/guide/emontx4/docs/overview.html
This will house both the existing documentation e.g emonPi and emonTx v3 in addition to the new hardware. This new implementation builds directly from the documentation placed in e.g the emonTx4 GitHub repository itself, so you can choose to either view the same documentation on github or with the nice ‘Read the docs’ theme.