twinlooper

Python code to interact with Rowin Twin Looper effects pedal

This project started as a discussion on the loopertrx project, which supports other pedals. https://github.com/reinerh/loopertrx

It quickly transpired that my TwinLooper pedal (and others) did not support the same (USB Mass Storage) protocols, instead using Midi SysEx to communicate. From a WireShark log I was able to identify some aspects of this and have started this project.

At this time it should be considered Experiemental, there is a high chance that it could do something bad to your pedal (though mine seems OK so far).

Message format

The messages to and from the pedal appear to have similar format. They are Midi SysEx format, starting F0 and ending F7. I used the Python module mido, which automatically strips these off

host    1.3.2   f0:00:32:0d:41:00:00:40:00:00:60:67:7b:20:00:00:00:04:01:f7

The other thing about midi is that it is (mostly) 7-bit information, so in-order to communicate 8-bit it needs to be packed into 7-bit format.

host    1.3.2   f0:00:32:0d:41:00:00:40:00:00:60:67:7b:20:00:00:00:04:01:f7
                ==                                                       == SysEx
                                           [<------ Packed Data ------>]
                                     ^^ ^^ command ??
                            ^^ ^^ ^^ count of bits in packed data (7-bit)
                   ^^ ^^ ^^ Midi device ID

Unpacked Data:
00000000: 00 F0 79 0F 02 00 00 84                           ..y.....
                               ^^ Checksum
                      ^^ ^^ ^^ Byte count requested
          ^^ ^^ ^^ ^^ Address

Much is to be discovered, and understood, but I have been able to pull an audio block from the pedal...

Audio can be created on PC with 'play' (from 'sox' package), and recorded on to pedal.

$ play -V -r 48000 -n synth sin 1000 vol -10dB
$ play -V -r 48000 -n synth sin 2000 vol -10dB