DIY- XESC Adapter for Surface Radios




About: Mechatronics Engineer . Hopeless Realist
First of all, this is not an ESC. Its an adapter that lets your use non-reversible ESCs like the ones used in model aeroplanes with a surface radio or pistol grip radios. It goes in between the Rx and ESC. This DIY is based on Arduino. Although, there's already an adapter called Pistix available in the market for the same purpose, I couldn't find any schematics or instructions about how to build one myself (I didn't want to pay $5+shipping). So I designed my own for a little over Rs.100 ($1.52).

An aeroplane ESC needs 0% throttle indication at startup, but since a surface radio throttle is set at about 25% by default, it makes the ESC beep as a warning to set the throttle to 0%. For the aeroplane ESC to work, you can either mechanically modify the Tx by setting the default position of the throttle to 0% or if that is not possible, you can do it the software way; the adapter takes the 25% signal coming from the Rx and remaps it to 0%, as an indication of 'no throttle' to the ESC.
I used an ATmega8 for this project just because I had a bunch of those laying around, it's definitely an overkill.
The microcontroller of your choice for this project must have flash memory in upwards of 4 KB and have 16-bit timers. If it's a 3.3v chip, then you'll have to do some level shifting. An ATtiny44 or ATtiny88 would be apt.
Materials required:
1) ATmega8 or equivalent microcontroller- 1 nos
2) 16MHz crystal (one that matches your chip) - 1 nos
3) 22pF ceramic capacitors- 2 nos
4) Servo extender- 1 nos
5) Strip board
Additionally, you'll need an USBasp programmer to burn the code on to the ATmega8.
However, I used an Arduino UNO board for the same.
I did this in an hour with ugly hardwires on a piece of strip board. I urge you to do it on a nice PCB, if you need help designing the PCB for your microcontroller, ask. I'll be glad to help.
Good luck, DIYers!



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    6 Discussions


    Reply 4 years ago

    The adapter works perfectly and doesn't need and further tweaking, please check your connections and verify the signal parameters of your ESC. I've used this for over a year with different ESCs without any problems.

    Also, I've made a ver.2 using a ATtiny45, its far smaller than this, please check my Instructables.


    4 years ago on Introduction

    I am a bit confused here.

    Where do the servo extender connect?

    I get PD6 & PB1. I guess VDC?

    But what about the other side? (You show two)

    1 reply

    Reply 4 years ago

    The ESC signal lines connect to a couple of digital pins on the Mega8 and the positive/red and ground/black wires are paralleled.


    5 years ago on Introduction

    I think AtMega8 is too big for aeroplane. Better is ATTiny84 or 85, but the second one doesn't have 16-bit timer. But both are much smaller, and ATTiny84V allows you to work with lower voltages like 1,8V, when 4MHz is enough for you.

    1 reply

    Reply 5 years ago on Introduction

    This adapter doesn't go on an aeroplane, its for RC cars and boats that use pistol-grip style surface radios. I use mine on a RC air boat, it's not too heavy but making it smaller is always an added advantage.
    An ATtiny44 is apt since it has 16-bit timer, 4KB flash which is plenty and they come in a small package. If you can set the fusebits of the TIny44 to run at 8MHz internally, you can eliminate external oscillator and a couple of crystals, you can directly use the microcontroller chip without and need of supporting components!