Re: Zoom G2Nu, G2.1Nu MIDI control

[Jacob Lister <jacob.h.lister@gmail.com>]

Here's my very rough guide to Zoom MIDI control, if anyone has any joy getting the Zoom to do MIDI tempo sync, I'd like to know - looking into wiring into the control input on the unit to do this, but I'd far rather do it over the USB midi interface

Zoom G2.1Nu MIDI Implementation notes:

In addition to the audio interface provided over USB on the G2.1Nu a MIDI interface is also provided for control purposes.  Unfortunately the MIDI interface is not mentioned in the Zoom product documentation :( . However, bundled with the product is control software called 'Edit and Share', which uses the MIDI interface to interact with the device.  Therefore it is reasonable to assume that any control avaliable with this software can be initated by sending MIDI messages to the device.

Setup
=====

The information in this document has been attained by analysing the messages sent to and from the G2.1Nu from the Edit & Share software.  This has in turn been attained by monitoring raw USB USB bus packets which are standard USB encapulated MIDI packets.  The hardware used for this was a G2.1Nu and a PC running Windows 7, the G2Nu has not been tested but will likely use the same format

Simple MIDI messages
====================

The G2.1Nu responds to several common MIDI messages out of the box with no special setup required.  
These are

Patch Change:
Sending a MIDI patch change message in the format 
 C0 {patch}

Will cause the Zoom to switch its current patch

MIDI CC message:
MIDI CC message are responsed, these can be used to turn on and off effects in the Zoom effects chain in stopbox functionality
 B0 {cc no} {value}
 
A value of 00 will turn the parameter off, 7F will turn the parameter on
 
The following CCs are responded to:
65 - Comp On/Off
66 - Efx On/Off
68 - Drive On/Off
69 - EQ On/Off
70 - ZNR On/Off
71 - Modulation On/Off
72 - Delay On/Off
73 - Reverb On/Off
74 - Mute On/Off
75 - Bypass On/Off

Extended Messages
=================

Further control of the Zoom it achieved with MIDI SysEx messages.  The Zoom needs to be sent some preamble with will place it in an operation mode where it will receive sysex messages to set control parameters, once in this mode it will also generate messages when parameters are modified on the Zoom.  The preamble is:

Tx: F0 7E 00 06 01 F7 - MIDI System common device identity request
Rx: F0 7E 00 06 02 52 4D 00 00 00 31 2E 30 33 F7 

Tx: F0 52 00 4D 50 F7
Tx: F0 52 00 4D 33 F7


The Zoom will now respond to further SysEx messages to set parameters, send SysEx parameters when they are modified on the Zoom, and send Patch Change message when the current patch is 
changed on the zoom via the stop box switches.

The SysEx parameter change message format is the same in both directions, the basic format is:

F0 52 00 4D 31 {param} {value} F7
param: parameter index, two bytes
value: parameter value, two bytes

For example setting master patch level to '50' is
F0 52 00 4D 31 0A 02 18 00 F7

Tempo Set
=========
The Zoom responds to a tempo change message as a SysEx parameters described above.  There does not however appear to be a way to send a tap tempo event along with the tempo change - the change is applied when the zoom has finished its current bar at the current tempo.  A workaround is possible however:

At the start of each beat, send:
F0 52 00 4D 31 0A 07 7A 01 F7 - Set Tempo to top of scale (250 bmp)
F0 52 00 4D 31 0A 07 78 00 F7 - Set Desired tempo (120 bmp in this example)

This will trick the zoom into locking onto the tempo set messages as a clock reference, it dosn't work perfectly however, and confuses some effects (delays tend to lost their last delay buffer on the change)

Expressions Pedal
=================
There does not appear to be any way to generate control message when the expression pedal is adjusted :( However, a SysEx message is generated when the expression pedal is pressed above top of scale (this usually switches the effect the pedal was controlling on/off)