Thanks for this tutorial. I converted a Vox V845 wah to an expression pedal, for my HX Stomp XL. Took everything out of the enclosure and put in a latch switch, Switchcraft stereo jack input and a TAD wah wah pot. The expression pedal is now more or less off/on from 50% so I need to solder in a 100kOhm resistor for better performance, as the pot is 100kOhm.
I'm still messing around with the settings. When I'm pressing the switch, in global settings, I get the warning "EXP 1 ACTIVE" and pressing the switch again it shows "EXP 2 ACTIVE". However, when trying to set the parameters in the effect blocks, EXP1 doesn't do anything. It needs to be EXP2 for it to work. For example, I have a preset with both an volume and wah block. With the toe switch, I can bypass the volume block and activate the wah block at the same time or vice versa. "Position" parameters are controlled by EXP2 for both the volume and wah block. Works fine but I get the idea that it could work without controlling both blocks at the same time.
Shouldn't it be possible that the pedal's function EXP2 gets toggled with the toe switch to EXP1? I have the L6 Mission that I use on my Helix Rack to work like that.