Midi/Expression Add on Board

[Peetem]

Three quick noob midi questions -

I am using the USB port to receive midi signals from my Arduino.  I also have added the midi/expression pedal add on board.   Both work great.

1) Does the midi-out on the add on board work when using the usb port to receive midi-in signals? 
2) Does the expression pedal also connect to other devices when using the same out port?
3) Can the output port send a signal via USB or do I need to use the 1/8" jack to 5-pin midi adapter and then another adapter to USB.

I am looking to change one of my amps to one that also has midi control.  I want to change channels on the amp and use the expression pedal as a volume control for the same amp.

Thanks!

[Randall (Admin)]

It sounds like your main goal is to use MIDI out from the pi-Stomp (USB or TRS) to control your amp, right?

I have to admit that the main focus for the MIDI offerings on pi-Stomp have been as a receiver of MIDI messages, not sender.  That said, Alsa is quite powerful and configurable, so you should be able to achieve that.

1) Does the midi-out on the add on board work when using the usb port to receive midi-in signals?

The two should be independent.

2) Does the expression pedal also connect to other devices when using the same out port?

The expression pedal input is used as a MIDI CC control configured via default_config.yml (MIDI chan, CC message, etc.)  Alsa will recognize it as a MIDI device which you should be able to use to control other applications running on the pi.  It should be routable to other MIDI devices via ALSA.  If you're asking can it be routed out of the pi-Stomp to control another physical device, I've not tried that, but it seems like it should be possible.

3) Can the output port send a signal via USB or do I need to use the 1/8" jack to 5-pin midi adapter and then another adapter to USB.

USB MIDI is a separate device (with input and output) than the serial MIDI device that the MIDI+Exp board offers.  You should be able to route between the two via Alsa, but again, I've not tried.

[Peetem]

Perfect, thank you.

My first midi controller works very well, but now I'm building one which has even more flexibility.  I will be using the Pi Stomp as my primary effects and I also bought a new amp.  Since both the amp and Stomp accept midi to control parameters, I wanted to make sure that my controller didn't send midi signals to both the amp and Stomp confuse my amp (if this makes sense). 

Fortunately I added more buttons to my controller, but configured those to send program control messages (PC) and not CC.  I also configured the controller to send midi serial via the USB and midi PC through a 5-pin din.  So I basically have two outputs from my controller that are independent.

The new controller will take this same approach but have more CC buttons, PC buttons, and Bank buttons.  I've programmed it to store up to 16 banks of any CC/PC combination as well as save and delete banks via a micro SD module (I upgraded my Arduino to a Mega from the Teensy).  The buttons also light showing what's active.

I got tired of hauling around two 120W amps and wanted to run direct (too old for loud stage volume and our PA is massive) - but I needed to be able to change channels on the amp (I have 12 on it, but would never use more than 4) and not have the built in effects triggers from incoming CC messages (which it also accepts for the multiple parameters and effects). 

The Pi Stomp has allowed me to have more flexibility than ever before.  Amazing device.

[Randall (Admin)]

I'm glad you're enjoying your pi-Stomp and doing cool things with it.

"I wanted to make sure that my controller didn't send midi signals to both the amp and Stomp confuse my amp"

That's a main reason MIDI has multiple channels.  You could have your pi-Stomp mappings on Chan1 and your amp on Chan2.  CC's or PC's sent on one channel will be ignored by the device listening on the other.  That does assume that your controller supports programming the channel with each CC/PC.  Some controllers might only send on one channel or all (omni).