Saturday, 5 April 2014

HobbyKing HK310 AUX channel hacking

It turned out that modifying the HobbyKing HK310 transmitter in order to change the behavior of the AUX (CH3) channel is quite easy:

WARNING: This and other DIY projects are purely "at your own risk". If you are at all uncomfortable or inexperienced working with electronics, please reconsider doing the job yourself.

All documentation details and sample source code for Arduino and PIC microcontrollers can be found at

With the information found in this project you can modify a HobbyKing HK310 or a Turnigy X-3S transmitter to send arbitrary information on the three channels to the receiver. This allows for example to:

  • Change the AUX channel from a two position switch to a three position switch
  • Change the AUX channel to an analog channel
  • Perform custom mixing on any of the channels
  • Transmit arbitrary data over the AUX channel to a custom decoder as to expand the system to a large number of on/off channels, e.g. to control lights and accessories on a scale RC truck
  • Build your own custom transmitter by just reusing the wireless module

Happy RC-ing!


  1. a Question.. The HK-300 has another protocol, would it be possible to copy the firmware from a HK310-> HK300 transmitter card ? I ask, because i purchased a couple of 310's and one of them was DOA. i found out it was the transmitter card, and if i can just copy the firmware from one transmitter card to the other, then i could use the one from my old HK300. Br Browsem

    1. Hi! The nRF24LE1 chips that I have seen in both the HK-310 and HK-300 are OTP versions, which means they are one-time programmable in the factory and unfortunately cannot be re-programmed.

  2. This comment has been removed by the author.