00 Simple MIDI
Simple MIDI turns the Computer into a two-channel USB MIDI interface over the front USB-C connection. Incoming MIDI notes, pitch bend and CC 42 become calibrated pitch CV, gates and CV; the knobs, switch and inputs are sent back as MIDI CCs. It works as a MIDI device (connected to a computer) or as a MIDI host (connected to a MIDI controller). It is also used, with a web page, to calibrate the Computer's precision CV outputs and its audio and CV inputs. The calibration is saved on the Computer and used by other cards.
Panel
CC 34CC 35CC 36CC 38CC 39CC 40CC 41CH 1 CC 42CH 2 CC 42CH 1 PitchCH 2 PitchCH 1 GateCH 2 GateControls
CC 34
Sent to the host as MIDI CC 34 on channel 1
CC 35
Sent to the host as MIDI CC 35 on channel 1
CC 36
Sent to the host as MIDI CC 36 on channel 1
CC 37: Sends MIDI CC 37 value 127
CC 37: Sends MIDI CC 37 value 64
CC 37 / Calibrate: Sends MIDI CC 37 value 0. Hold down while pressing Reset/Load to start calibration mode, which is controlled from the calibration web page.
Inputs & Outputs
Inputs
Outputs
Inputs
CC 38
Sent to the host as MIDI CC 38 on channel 1
CC 39
Sent to the host as MIDI CC 39 on channel 1
CC 40
Sent to the host as MIDI CC 40 on channel 1
CC 41
Sent to the host as MIDI CC 41 on channel 1
Outputs
CH 1 CC 42
MIDI channel 1 CC 42 output as CV, approximately -5V to +5V
CH 2 CC 42
MIDI channel 2 CC 42 output as CV, approximately -5V to +5V
CH 1 Pitch
Calibrated 1V/octave pitch CV for the last held note on MIDI channel 1, with +/-2 semitone pitch bend
CH 2 Pitch
Calibrated 1V/octave pitch CV for the last held note on MIDI channel 2, with +/-2 semitone pitch bend
CH 1 Gate
High while any note is held on MIDI channel 1
CH 2 Gate
High while any note is held on MIDI channel 2
LEDs
CH 1 CC 42
Brightness shows the channel 1 CC 42 value
CH 2 CC 42
Brightness shows the channel 2 CC 42 value
CH 1 Pitch
Brightness shows the channel 1 note number
CH 2 Pitch
Brightness shows the channel 2 note number
CH 1 Gate
On while a note is held on channel 1
CH 2 Gate
On while a note is held on channel 2
README
Simple MIDI (v0.7)
Simple MIDI turns the Music Thing Modular Workshop Computer into a USB MIDI interface. It sends controls and CV from the Workshop System to a computer, and turns incoming MIDI notes, gates, pitch-bend and continuous-controller messages into CV and gate signals.
It is also the card used to calibrate the Workshop Computer's two precision CV outputs and audio inputs. Other cards, including Turing Machine and Reverb+, can use the saved calibration data so that their pitch outputs play in tune.
Simple MIDI was written by Tom Whitwell in Herne Hill, London, between October 2024 and October 2025 (versions up to 0.6.6), and revised by Chris Johnson in Derbyshire between March and August 2026 (version 0.7.0-)
What it does
Simple MIDI receives two channels of MIDI from a connected MIDI device:
- Note pitch
- Note on/off gates
- Continuous Controller 42
- Pitch bend
It sends eight controls from the Workshop System back to the MIDI device:
- Main, X, and Y knobs
- The Z switch
- Both Audio/CV inputs
- Both precision CV inputs
Simple MIDI can act as a MIDI device (for connection to a computer) or as a MIDI host (for connection to MIDI controllers). The Workshop System appears on the connected computer as MTMComputer MIDI or Music Thing MTMComputer MIDI.
Watch the 90-second Simple MIDI introduction on Instagram.
Connecting to a computer
- Connect the Workshop Computer's front-panel USB-C port to a computer running a MIDI sequencer or DAW.
- Cycle the Workshop System's power. Power cycling, rather than only pressing Reset, ensures that the Workshop Computer detects the USB host.
- Insert the Simple MIDI card with its gold connector facing down.
- Press the small Reset/Load button beside the Program Card slot.
- The LEDs should blink briefly and then stop.
- Select MTMComputer MIDI or Music Thing MTMComputer MIDI in your DAW or MIDI software.
If the LEDs continue blinking, the USB connection has not been established:
- Turn the Workshop System off and on again.
- Check that the USB cable supports data. Some USB-C cables provide power only.
- Try another USB port or cable.
The Workshop Computer does not need to connect to a USB-C socket on the host; a USB-A-to-USB-C data cable is also suitable.
MIDI controls
Workshop System to computer
| Workshop Computer control | MIDI message |
|---|---|
| Main knob | CC 34 |
| X knob | CC 35 |
| Y knob | CC 36 |
| Z switch | CC 37 |
| Audio/CV In 1 | CC 38 |
| Audio/CV In 2 | CC 39 |
| CV In 1 | CC 40 |
| CV In 2 | CC 41 |
Computer to Workshop System
| Workshop Computer output | MIDI input |
|---|---|
| Audio/CV Out 1 | Channel 1, CC 42 |
| Audio/CV Out 2 | Channel 2, CC 42 |
| CV Out 1 | Channel 1 note pitch |
| CV Out 2 | Channel 2 note pitch |
| Pulse Out 1 | Channel 1 note on/off |
| Pulse Out 2 | Channel 2 note on/off |
Calibrating the Workshop Computer
For full details on how to calibrate the Workshop Computer and Workshop System oscillators, see the complete Workshop System calibration guide.
Using the calibration data
For more details check the Technical notes