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DIY Transmitter


Custom Hardware

Possibly one of the biggest benefits of using ExpressLRS is custom hardware!

Custom ESP 2.4 GHz TX (for JR module bay)

All of the info on this topic can be found here

custom tx

Custom Super Slim ESP 2.4 GHz TX (for lite module bay)

The super slim is an evolution of the slim. It uses the same base hardware as the JR size one. It's the same size as an R9M Lite, and fits in all handsets with a lite module bay such as the X-Lite, X9 Lite, and Tango 2 (with the proper adapter). The rest of the info can be found here

custom tx slim

Custom 900 MHz TX (not built anymore)

In the beginning, 900 MHz transmitters were sometimes built DIY. Today they're not. If you have one, the max output power defaults to 100mW, but with UNLOCK_HIGHER_POWER, that can be increased to 250mW.

Custom Hardware's Firmware Guide

PlatformIO is a prerequisite for developing custom hardware.

The hardware pinouts for ExpressLRS are kept at ExpressLRS/targets. Clone this repo within src/ of your ExpressLRS/ExpressLRS repo - or, if you run a build, it'll happen automatically.

In the RX and TX directories, you can find the pinouts and configuration for different layouts stored as JSON files.

Within targets.json, there are listed all the possible build targets for ExpressLRS.

To access your target's configuration, you must add a new entry to the targets.json file - mimic the closest existing one and change the values to match your hardware. It's critical the firmware field match your processor.

Select the matching build target from PlatformIO:

After you run a build, you should be met with a hardware configuration selector and your new configuration!