CH Pro Throttle to USB and Slew Mod

Lov · February 7, 2021

Hi,

I'm not active here, but I took a lot of info from your posts, in order to do this small project so I'd like to share the result.

Essentially what I started out to do is turn a CH Pro Throttle game port version into a USB throttle.

The Ch Pro Throttle comes with one low-ohm poti for the throttle axis. Four dedicated buttons and four digital four-way hats make for 20 buttons, which are wired into a button matrix.

In a first step I took an arduino sparkfun pro micro and the MMjoy firmware. I wired up the button matrix, liberally reusing the available cables and connectors. The poti also needed some rewiring, as the gameport joystick "protocol" is just wired to read resistance of an analogue axis poti, while the arduino already expects a voltage divider setup.

Now since I really enjoy the AV8B I decided to add more potis to the throttle grip.

And, to my demise, I found @rel4y's excellent Playstation thumbstick mod 3D printed parts, which replace the index finger 4-way hat with 2 analogue axes and a push button; which is really nice for the TDC slew and TDC down/action part of a HOTAS. You already see that I was quickly running out of arduino inputs. Therefore I decided to use an MCP-3208 ADC to digitize all 5 analogue axes. This required me to put a static resistor into the voltage divider of the slider axis, to reduce the charge going into the ADC at each sampling interval.

I know my mechanical skills are crude, please bear with me. After some hours of soldering and grinding I now have this nice USB throttle, and still 3 analogue axes and 3 buttons not used in hardware. Also when I'm grown up I maybe use some shift registers to put even more buttons.