Why doesn’t my expression pedal go to 100?

Different expression pedal resistances need to be configured with the Atmosphere.  Remove the power from your Atmosphere, plug in your expression pedal and set it to the maximum (toe down) position.  While holding down both stomp switches on your Atmosphere plug in the power.  Keep holding down the stomps until the pedal loads and your expression input will be set and will go 0 to 100.