Guitar Input Too Loud?

Hi
I have recently assembled a pedalSHIELD guitar pedal and it is pretty interesting. I have found one issue however.

When I first started to play with it everything was distorted so I used the adjust_trimmer program to set my guitar volume. Strangely, I have to turn my guitar volume all the way down to 2 (out of 10) for it to be within the volume parameters. This makes it extremely difficult for me to use it as I have to adjust the volume of my guitar when I use the pedal.

The purpose of a pedal is to change the effect in the middle of the song instantly and I can't do that currently with this pedal. Is there a way I can fix this by programming the pedal so that it reduces the input volume first before applying the effects?

I'm using a Squier Bullet Stratocaster with a Powered by Lace Humbucker.

P.S. Is it possible that I need to adjust the trimmer resistor RV1?

The input range of the Arduino ADCs is from 0 to 3.3V.
When the guitar is connected to pedalSHIELD, the input stage can adjust (with VR1) the voltage coming from the guitar to the optimum range for the Arduino DUE ADC.

• With VR1 to the minimum: Voltage gain is 1 time. (no gain)
• With VR1 maxed out: Voltage gain is 26 times.

The situation you are mentioning is odd because with minimum gain (gain=1), you should have a guitar pickups with an output voltage of 3.3V to saturate the ADC (which is not very probable).

The most probable situation is that one of the resistors of the input stage are swapped, giving too much gain.

Could you double check this resistors or update a picture of your PCB for us to check it?

Thanks JR for your help.

It is a little embarrassing but it turns out that I got RV1 all the way down so it is clipping every sound I play through my guitar . It is working perfect now after I adjusted it.