MIDI

From v0.11 (v0.10 takes MIDI clock only). FRIZZ takes MIDI from the TRS MIDI input and over USB (CHOMPI is a USB device, so USB MIDI comes from a computer or a host), both alike. It sends nothing over TRS; over USB it only answers FRIZZ’s own queries (see Remote control).

MIDI clock

Quantized recording, and the effects’ tempo while there’s no loop, follow MIDI clock (24 PPQN). Whichever source ticks first is used, until it has been silent for 0.5 s. The clock is read on every channel.

The clock factor on the settings page makes FRIZZ follow the clock at half its tempo or at double: a DAW at 70 BPM with FRIZZ thinking in 140, or the other way round. It counts for everything that follows the clock: the bars of a quantized recording and the effects’ tempo. A loop, once there is one, keeps its own tempo. Changing it while a quantized recording ends that recording where it is, as a lost clock does.

Channel

Notes, controllers and program changes count on one channel: 16 at first, the one a setup sending notes to other instruments over the same cable uses least. FRIZZ keeps it on the card, in FRIZZ/frizz_master.txt (midi_channel 16; 0 listens on every channel). Change it on the settings page, in the file, or from a computer with firmware/remote.py channel N.

Notes: the keys

A note holds the key it lands on while it’s on, as your finger would: an FX key punches its effect in, a scene key recalls, and so on. The 25 keys are a keyboard from note 48 (C3, or C2 in Ableton Live): the white keys from 48 up, the dark keys on the sharps. Below them:

Note	Key
36, 37, 38, 39	Knob 1, 2, 3, 4 pressed
40	The transport knob pressed
41	VOLUME pressed
45	CHOMPI (SHIFT)
46	PLAY
47	LOOP

• A key held by your hand and by a note is pressed once, and let go when both have let go.
• The velocity doesn’t matter; a note on at velocity 0 is a note off.
• All Notes Off (CC 123) or All Sound Off (CC 120) lets go of every key MIDI holds, for a note off that went missing.

Controllers

CC	Function
14, 15, 16, 17	Knob 1, 2, 3, 4 turned, relative: 1-63 turns that many detents right, 127-65 that many left (two’s complement). SHIFT held turns coarsely, as by hand
18	The transport knob turned, relative
19	VOLUME turned, relative, on the page it’s on
20-31	An effect’s latch, by its key left to right (20 the freezer, 30 the delay, 31 the reverb): 64 and above latched, below off
52, 53, 54, 55	The master compressor’s amount, ratio, speed and mix
56	Output gain
57	Input gain
58	Input/loop mix
59	Headphone feed: 0 the master out, 127 the AUX input on its own
60	Mono input: 64 and above mono, below stereo
61	How many bars a morph over CC 62 takes, 1-8 (1 at first)
62	Morph to scene 0-4 (0 the blank one): as SHIFT + its key, landing on the bar line
63	64 and above: stops a morph where it is
70-117	An effect’s knob, set outright: 70 + 4 × the effect + the knob − 1, the effects counted from 0 by their keys: the freezer 70-73, shifter 74-77, folder 78-81, crusher 82-85, filter 86-89, flanger 90-93, resonator 94-97, slicer 98-101, wow & flutter 102-105, tape stop 106-109, delay 110-113, reverb 114-117

• Set outright (CC 20-117), a value does what the knob or key would: the LEDs follow, the scene key pulses as edited, a morph lands where the CC put the parameter, a send ringing out takes it when its key next comes on. The knobs stay on the effect you picked. 64 is a knob’s centre exactly (the filter’s flat cutoff, a delay’s random off), 127 its top. Stepped parameters take the nearest step.
• 14 bits: NRPN with the CC’s number as the parameter (NRPN MSB 0, LSB the CC) sets it in 16,384 steps (8192 the centre): CC 99 0, CC 98 the CC number, CC 6 the value’s top 7 bits, CC 38 its bottom 7.
• Mod wheel, pitch bend, aftertouch and other controllers are ignored.

Program changes

Program change 0-4 presses scene key 0-4 (0 the blank scene): a recall, or in a save, copy or delete mode the slot. 5 and above are ignored.

Start and Stop

With transport following on, MIDI Start and Continue play the loop and Stop pauses it, so a DAW’s play button starts and stops the loop with the song. It’s off at first; switch it on on the settings page (D# of the lower octave), with firmware/remote.py transport on, or midi_transport 1 in FRIZZ/frizz_master.txt. Start plays on from where the loop is, as Continue does: the loop doesn’t jump to its start.

Remote control

FRIZZ’s own SysEx (F0 7D 43 48 ..., documented in firmware/code/src/MidiControl.h) presses keys, turns knobs, sets the channel and holds the mode switch up or down (until power-off) on every channel; its keys and knobs act as your hands do, on the settings page too, and over USB answers what the play page shows, every LED, the processing load, and sends and receives scenes. firmware/remote.py uses it from a Linux computer: state, leds, load, switch up|down|hand, scene get 2 my.json, scene put 3 my.json, and play SCRIPT --cpu, which plays a scenario of the virtual CHOMPI on the device and reports the worst load.