Thursday, July 21, 2011

I'm going to call this progress.

So, I managed to patch into the controller for the joystick and took a quick video to show progress.

The hardest part of this so far was using the wrong set of transistors (Which are being used to digitally simulate a button press on the controller). I was using medium power, when I needed to be using the BC108 low power transistors.

This is because the switches on the controller itself are going off 3.3v, and I was trying to switch them using a 5v signal from the arduino. I swapped to low power transistors, and threw in a resistor to reduce the voltage going into the transistor, and now it works a charm.

I also wasted a fair bit of time digging out the spec for the joystick from the archives of the internet, which basically tells me, I need to look for an easier way to control the motors than trying to replicate the joystick itself.

See the spec for the joystick here:
D50800-03 Specification

More progress soon I hope.


  1. Hello Justin,

    Firstly, I want to congratulate you on your success. I have been working on a similar hack myself, gaining control of the wheelchair base via the joystick. I came across your blog when I decided to go further than just controlling the motors and gain control of the power and speed as well. I am curious to see how you wired the buttons to the arduino. Would you show me your schematics?

    Also, would you mind sharing your arduino code as well.


    Jeff in Tokyo

    1. Concerning controlling the motors via the joystick: instead if using pwm pins from the Arduino I used two DACs to generate the 2.5V that the chairs safety logic is looking for at startup. These DAC voltages can then be manipulated from 1.8 (for backward ) to 3.8V (for forward) . The voltage swing similarly vary for left/right. The other pins on the controller get their static value from the joystick circuit.