8mu CV

A playable, unpredictable instrument as much as a showcase for the Music Thing 8mu: every control it has - the eight faders, the four top buttons, and the accelerometer - drives the Workshop Computer's outputs. Set the LFOs running and latch in the accelerometer, and the controller steers voltages, rates and widths you didn't quite dial in - surprising, and often musical. It is also a way to test an 8mu channel by channel. The audio outputs are DC-coupled, so they carry steady voltages just as well as sound, giving four bipolar voltage sources rather than the usual two.<br><br>

Faders 1-4 set the levels of Audio Out 1, Audio Out 2, CV Out 1 and CV Out 2, each running from about -5V at the bottom through 0V in the middle to about +5V at the top. Faders 5 and 6 set the rates of Pulse Out 1 and Pulse Out 2: independent pulses from 0.1Hz to 20Hz, exponential across the fader so equal movements multiply the rate. Faders 7 and 8 set their widths: the middle is a 50% square, the way down narrows toward a sharp trigger, the way up widens toward a gate that stays open nearly all the time.<br><br>

The Computer's switch picks the mode. Middle is the basic card. Up is LFO mode: a tap on a top button arms that output, capturing the voltage it is already at as the centre for a triangle LFO, with the fader then setting the speed. The Main knob sets how far the triangle swings, always measured to the nearer supply rail, so it can never clip.<br><br>

Holding the switch Down for half a second latches the accelerometer on or off. When it is on, the four gesture axes take over the four voltage outputs and their LFO rates: Pitch and Roll (tilt), Yaw (spin), and Flip (which way up, unipolar so a flat 8mu reads 0). The X knob scales how far the gestures respond and the Y knob smooths them. The three panel knobs are otherwise not a fallback, since the point of the card is to drive the 8mu; unplug it and the outputs hold their last values.<br><br>

The card is a pure MIDI listener: it never writes to the 8mu's LEDs or settings, so the controller behaves exactly as it does anywhere else. It needs a Rev 1.1 or later Computer, and nothing else may be in the front USB socket, because the Computer has to act as a USB host.

Copy the UF2 onto the Computer's program card (RP2040 bootloader drive).