# AMY synthesizer API

This page collects the current API for [AMY](https://github.com/shorepine/amy).

[**Please see our interactive AMY tutorial for more tips on using AMY**](https://shorepine.github.io/amy/tutorial.html)

## C / Arduino API

Parsing, creating and adding events to AMY:

```c
// returns default empty amy_event
amy_event amy_default_event();

// clears an existing AMY event
amy_clear_event(amy_event *e);

// given an event play / schedule the event directly
amy_add_event(amy_event *e);

// given a wire message string play / schedule the event directly
amy_add_message(char *message);
```

Get and set external audio buffers:
```c

// get AUDIO_IN0 and AUDIO_IN1
amy_get_input_buffer(output_sample_type * samples);

// set AUDIO_EXT0 and AUDIO_EXT1
amy_set_external_input_buffer(output_sample_type * samples);
```

If not running live, render a new block of AMY audio into a int16_t buffer:

```c
output_sample_type * amy_simple_fill_buffer();
```

Get the AMY time:
```c
// on all platforms, sysclock is based on total samples played, using audio out (i2s or etc) as system clock
uint32_t amy_sysclock();
```


Start and stop AMY:
```c
// Emscripten web start
amy_start_web();
amy_start_web_no_synths();

// Start AMY with a config.  If c.audio is set, will attempt to start live audio
amy_start(amy_config_t c);

// Stop AMY including any live audio output
amy_stop();

```

Default MIDI handlers:
```c
void amy_enable_juno_filter_midi_handler(); // assigns the Juno-6 MIDI CC handler
```

## JavaScript API

AMY provides a high-level JavaScript API (`amy_send`) that mirrors the Python `amy.send()` interface. It is auto-generated from the same source of truth (`amy/__init__.py` and `amy/constants.py`) so parameter names are always identical to Python. The connector and API are bundled into `amy.js`, so you only need two includes:

```html
<script src="enable-threads.js"></script>
<script src="amy.js"></script>
```

### `amy_send(params)`

Build and send an AMY wire message from a JS object. Parameter names and types are the same as Python `amy.send()`.

```js
// Play a sine wave at 440 Hz
amy_send({osc: 0, wave: AMY.SINE, freq: 440, vel: 1})

// Load a Juno-6 patch
amy_send({patch: 0, synth: 1, num_voices: 6})
amy_send({synth: 1, vel: 1, note: 60})

// FM synthesis with CtrlCoef dict
amy_send({osc: 0, amp: {const: 1, vel: 0, eg0: 2}, bp0: '0,0,5000,1,0,0'})
```

### `amy_message(params)`

Like `amy_send` but returns the wire string without sending it. Useful for debugging or building messages to send later.

```js
amy_message({osc: 0, wave: AMY.SINE, freq: 440})  // => "v0w0f440Z"
```

### `AMY` constants

All constants from `amy/constants.py` are available on the global `AMY` object:

```js
AMY.SINE         // 0
AMY.SAW_DOWN     // 2
AMY.PULSE        // 1
AMY.FILTER_LPF   // 1
AMY.ALGO         // 8
// ... all constants from amy/constants.py
```

### Regenerating

The JS API is generated during `make web` and bundled into `docs/amy.js` by `make deploy-web`. To regenerate after changing `amy/__init__.py` or `amy/constants.py`:

```bash
make deploy-web
```

### Try it live

[**AMY JavaScript REPL**](https://shorepine.github.io/amy/repl.html) — write and run `amy_send()` commands in your browser.

## `amy_config_t`

Use like:

```c
amy_config_t amy_config = amy_default_config()
amy_config.max_sequencer_tags = 128;
amy_start(amy_config);
```

| Field   | Values | Default   |  Notes                                 |
| ------  | ------ | --------  |  --------                              |
| `features.chorus` | `0=off, 1=on` | On | If chorus is enabled (uses RAM) |
| `features.reverb` | `0=off, 1=on` | On | If reverb is enabled (uses RAM) |
| `features.echo` | `0=off, 1=on` | On | If echo is enabled (uses RAM) |
| `features.partials` | `0=off, 1=on` | On | If partials are enabled |
| `features.custom` | `0=off, 1=on` | On | If custom C oscillators are enabled |
| `features.audio_in` | `0=off, 1=on` | Off | If audio_in gets processed via the audio interface. Must be 1 for AUDIO_IS_MINIAUDIO |
| `features.default_synths` | `0=off, 1=on` | Off| If AMY boots with Juno-6 on `synth` 1 and GM drums on `synth` 10 |
| `features.startup_bleep` | `0=off, 1=on` | Off | If AMY plays a startup sound on boot |
| `platform.multicore` | `0=off, 1=on` | On | Attempts to use 2nd core if available |
| `platform.multithread` | `0=off, 1=on` | On | Attempts to multithreading if available (ESP/RTOS) |
| `midi` | `AMY_MIDI_IS_NONE`, `AMY_MIDI_IS_UART`, `AMY_MIDI_IS_USB_GADGET`, `AMY_MIDI_IS_WEBMIDI` | `AMY_MIDI_IS_NONE` | Which MIDI interface(s) are active |
| `audio` | `AMY_AUDIO_IS_NONE`, `AMY_AUDIO_IS_I2S`, `AMY_AUDIO_IS_USB_GADGET`, `AMY_AUDIO_IS_MINIAUDIO`| I2S or miniaudio | Which audio interface(s) are active |
| `write_samples_fn` | fn ptr | `NULL` | If provided, `amy_update` will call this with each new block of samples | 
| `max_oscs` | Int | 180 | How many oscillators to support |
| `max_sequencer_tags` | Int | 256 | How many sequencer items to handle |
| `max_voices` | Int | 64 | How many voices |
| `max_synths` | Int | 64 | How many synths |
| `max_memory_patches` | Int | 32 | How many in memory patches to supprot |
| `i2s_lrc`, `i2s_dout`, `i2s_din`, `i2s_bclk`, `i2s_mclk` | Int | -1 | Pin numbers for the I2S interface |
| `midi_out`, `midi_in` | Int | -1 | Pin number for the MIDI UART pins |
| `midi_uart` | 0,1,[2] | -1 | UART device index for MCU. Default 1 (`UART1`) on Pi Pico and ESP. Teensy is always `8` |
| `capture_device_id`, `playback_device_id` | Int | -1 | Which miniaudio device to use, -1 is auto |


## Hooks

Hooks are configured on `amy_config_t` before calling `amy_start`:

```c
amy_config_t amy_config = amy_default_config();
amy_config.amy_external_midi_input_hook = my_midi_hook;
amy_config.amy_external_render_hook = my_render_hook;
amy_start(amy_config);
```

Hook fields in `amy_config_t`:

| Hook | Signature | Used by | Description |
| ---- | --------- | ------- | ----------- |
| `amy_external_render_hook` | `uint8_t (uint16_t osc, SAMPLE *buf, uint16_t len)` | — | Custom oscillator renderer for redirecting the output waveforms on an osc-by-osc level. Return 1 if handled, in which case that osc does not contribute to the normal output. |
| `amy_external_coef_hook` | `float (uint16_t channel)` | — | Provide external coefficient values (e.g. CV input). |
| `amy_external_block_done_hook` | `void (void)` | — | Called after each audio block is rendered. |
| `amy_external_midi_input_hook` | `void (uint8_t *bytes, uint16_t len, uint8_t is_sysex)` | — | Called when MIDI bytes are received. |
| `amy_external_sequencer_hook` | `void (uint32_t tick_count)` | — | Called on each sequencer tick. |
| `amy_external_fopen_hook` | `uint32_t (char *filename, const char *mode)` | `zT`, `zD`, `zF` | Open a file on host disk. Returns opaque handle. |
| `amy_external_fwrite_hook` | `uint32_t (uint32_t fptr, uint8_t *bytes, uint32_t len)` | `zT` | Write bytes to a file opened via fopen hook. |
| `amy_external_fread_hook` | `uint32_t (uint32_t fptr, uint8_t *bytes, uint32_t len)` | `zD` | Read bytes from a file opened via fopen hook. |
| `amy_external_fseek_hook` | `void (uint32_t fptr, uint32_t pos)` | `zD` | Seek to position in a file opened via fopen hook. |
| `amy_external_fclose_hook` | `void (uint32_t fptr)` | `zT`, `zD`, `zF` | Close a file opened via fopen hook. |
| `amy_external_file_transfer_done_hook` | `void (const char *filename)` | `zT` | Called after a `zT` file transfer completes. On AMYboard, restarts sketch.py. |
| `amy_external_update_file_hook` | `void (const char *filename)` | `zA` | Called by `zA` to update a file with current AMY state. On AMYboard, splices live knob state into sketch.py. |
| `amy_external_exec_hook` | `void (const char *code)` | `zP` | Called by `zP` to execute a string on the host. On AMYboard, runs the string as Python via `exec()`. |
| `amy_external_reboot_hook` | `void (uint8_t mode)` | `zB` | Called by `zB` to reboot the host. `mode` selects which post-reboot state: `0` = bootloader (skip sketch on next boot), `1` = normal reboot (run sketch), `2` = ROM download / flash mode. Handled in pure C before `mp_sched_schedule`. On AMYboard, sets an RTC flag with the requested mode and calls `esp_restart()`. |

All hook fields default to `NULL` in `amy_default_config()`.


## `amy_event`, `amy.send`, and `amy_send` API:

AMY parameters can be set via three interfaces:
- **C**: Set fields on `amy_event` structs
- **Python**: `amy.send(param=value, ...)`
- **JavaScript**: `amy_send({param: value, ...})`

Python and JavaScript use identical parameter names (shown in the **Python / JS** column below). A few parameters are not yet available via C `amy_event` (marked **TODO**).

Please see [AMY synthesizer details](synth.md) for more explanation on the synthesizer parameters.

[**Please see our interactive AMY tutorial for more tips on using AMY**](https://shorepine.github.io/amy/tutorial.html)

A note on list parameters:  When an argument is a list of parameters, you can in general set any subset of those parameters by omitting the values you don't want to change - either by leaving them in their initial `AMY_UNSET` value in C, or by having missing values in Python lists.  For instance, you can set up an envelope that moves immediately to 1, then decase to a sutain level of 0.5 over 200ms, then has a 300ms decay to zero on note-off, with `bp0='0,1,200,0.5,300,0'.  Subsequently, you could change just the sustain level (the 4th value in the list) to 0.2 with `bp0=,,,0.2`.  However, there's at present no way to say ".. and the list should now only be 4 items long.  This only affects breakpoint sets which are variable length, but the net result is that once you have a certain number of breakpoints in a list, you cannot shorten it except by resetting the whole osc and building it all up again.


### `synth`s and `voice`s:

| Wire code   | C `amy_event` | Python / JS   | Type-range  | Notes                                 |
| ------ | -------- | ---------- | ----------  | ------------------------------------- |
| `i`    | `synth` | `synth`  | 0-31  | Define a set of voices for voice management. |
| `ic`   | **TODO** | `midi_cc`  | C,L,N,X,O,CMD | MIDI Control Code command for this synth (1-16).  `C`=MIDI CC (0-127), `L`=log mapping (0/1), `N`=min val, `X`=max val, `O`=offset, `CMD`=wire command to execute, where `%i` is replaced by the channel number and `%v` is replaced by the value after min/max/offset/log mapping.  Providing `C` with no further args deletes that CC.  `C=255` deletes all CC mappings for the specified synth. See [#524](https://github.com/shorepine/amy/issues/524) |
| `id`   | `synth_delay_ms` | `synth_delay` | uint | Delay (in ms) applied to synth note-ons.  Gives time for decay of 'stolen' notes. |
| `if`   | `synth_flags` | `synth_flags` | uint | Flags for synth creation: 1 = Use MIDI drum note->preset translation; 2 = Drop note-off events. |
| `ig`   | `cv_trigger` | `cv_trigger` | uint,uint | Configure external CV event triggering: Gate CV, trigger threshold, reset threshold, pitch CV, pitch scale, pitch offset, wire command template, %v gets pitch value. |
| `im`   | `grab_midi_notes` | `grab_midi_notes` | 0/1 | Use `amy.send(synth=CHANNEL, grab_midi_notes=0)` to prevent the default direct forwarding of MIDI note-on/offs to synth CHANNEL. |
| `iM`   | `note_source_channel` | `note_source_channel` | 1-16 | Used internally to mark events that result from MIDI inputs, meaning they won't get forwarded to MIDI out. |
| `in`   | `oscs_per_voice`  | `oscs_per_voice`  | >0  | Reserve this many oscs for each voice.  Needed when initializing a synth (or voice) withouth an initial patch. Setting `oscs_per_voice` on an existing synth resets all oscs to their default state. |
| `io`   | **TODO** | `midi_note_cmd`  | M,L,N,X,O,CMD | MIDI Note on/off command for this synth.  M=MIDI note number, or -1 for all notes.  Other args map the velocity, as for `ic`. `%n` is substituted with the note number. |
| `ip`   | `pedal` | `pedal` | int | Non-zero means pedal is down (i.e., sustain).  Must be used with `synth`. |
| `it`   | `to_synth` |  `to_synth` | 0-31 | New synth number, when changing the number (MIDI channel for n=1..16) of an entire synth. |
| `iv`   | `num_voices` | `num_voices` | int | The number of voices to allocate when defining a synth, alternative to directly specifying voice numbers with `voices=`.  Only valid with `synth=X, patch[_number]=Y`. |
| `iy`   | `bus`   | `bus`   | int | Bus onto which the synth outputs are added (synonym for `y`). |
| `K`    | `patch_number` | `patch` | uint 0-X | Apply a saved or user patch to a specified synth or voice. Built-ins: 0-127 Juno, 128-255 DX7, 256 piano, 258 legacy GM drums, 384-390 Gamma9001 GM drum kits (see Drum kits below), 1024+ user patches. |
| `r`    | `voices[]` | `voices` | int[,int] | Comma separated list of voices to send message to, or load patch into. |
| `u`    | **TODO**| `patch_string` | string | Provide AMY message to define up to 32 patches in RAM with ID numbers (1024-1055) provided via `patch_number`, or directly configure a `synth`. |


### Oscillator control

| Wire code   | C `amy_event` | Python / JS   | Type-range  | Notes                                 |
| ------ | -------- | ---------- | ----------  | ------------------------------------- |
| `v`    | `osc` | `osc` | uint 0 to OSCS-1 | Which oscillator to control |
| `w`    | `wave` | `wave` | uint 0-21 | Waveform: [0=SINE, PULSE, SAW_DOWN, SAW_UP, TRIANGLE, NOISE, KS, PCM, ALGO, PARTIAL, BYO_PARTIALS, INTERP_PARTIALS, AUDIO_IN0, AUDIO_IN1, AUDIO_EXT0, AUDIO_EXT1, AMY_MIDI, PCM_LEFT, PCM_RIGHT, WAVETABLE, CUSTOM, OFF]. default: 0/SINE |
| `S`    | `reset_osc`| `reset`  | uint | Resets given oscillator. set to RESET_ALL_OSCS to reset all oscillators, gain and EQ. RESET_TIMEBASE resets the clock (immediately, ignoring `time`). RESET_AMY restarts AMY. RESET_SEQUENCER clears the sequencer.|
| `A`    | `eg0_times[]`, `eg0_values[]` | `bp0`    | string (wire) / arrays (`amy_event`)      | Envelope Generator 0 breakpoints as time(ms),value pairs. Wire/Python format remains comma-separated, e.g. `100,0.5,50,0.25,200,0`. In C `amy_event`, use typed arrays (`eg0_times[i]`, `eg0_values[i]`). The last pair is release (triggers on note off). |
| `B`    | `eg1_times[]`, `eg1_values[]` | `bp1`    | string (wire) / arrays (`amy_event`)      | Envelope Generator 1 breakpoints. Wire/Python format remains comma-separated; in C `amy_event`, use typed arrays (`eg1_times[i]`, `eg1_values[i]`). |
| `b`    | `feedback` | `feedback` | float 0-1 | Use for the ALGO synthesis type in FM or for karplus-strong, or to indicate PCM looping (0 off, >0, on) |
| `c`    | `chained_osc` | `chained_osc` |  uint 0 to OSCS-1 | Chained oscillator.  Note/velocity events to this oscillator will propagate to chained oscillators.  VCF is run only for first osc in chain, but applies to all oscs in chain. |
| `G`    | `filter_type` | `filter_type` | 0-4 | Filter type: 0 = none (default.) 1 = lowpass, 2 = bandpass, 3 = highpass, 4 = double-order lowpass. |
| `I`    | `ratio` | `ratio`  | float | For ALGO types, ratio of modulator frequency to  base note frequency  |
| `L`    | `mod_source` | `mod_source` | 0 to OSCS-1 | Which oscillator is used as an modulation/LFO source for this oscillator. Source oscillator will be silent. |
| `m`    | `portamento`| `portamento` | uint | Time constant (in ms) for pitch changes when note is changed without intervening note-off.  default 0 (immediate), 100 is good. |
| `n`    | `midi_note` | `note` | float, but typ. uint 0-127 | Midi note, sets frequency.  Fractional Midi notes are allowed. |
| `o`    | `algorithm` | `algorithm` | uint 1-32 | DX7 FM algorithm to use for ALGO type |
| `O`    | `algo_source[]`| `algo_source` | string | Which oscillators to use for the FM algorithm. list of six (starting with op 6), use empty for not used, e.g 0,1,2 or 0,1,2,,, |
| `p`    | `preset` | `preset` | int | Which predefined PCM or wavetable preset patch to use, or number of partials if < 0. For `wave=WAVETABLE`, use the wavetable presets appended to PCM. (Juno/DX7 patches are different - see `patch_number`). |
| `p`    | `preset` | `num_partials` | int | Alias for `preset`. Must be used with `wave=BYO_PARTIALS`. Cannot be combined with `preset` in the same message. |
| `P`    | `phase` | `phase` | float 0-1 | Where in the oscillator's cycle to begin the waveform (also works on the PCM buffer). default 0 |
| `R`    | `resonance` | `resonance` | float | Q factor of variable filter, 0.5-16.0. default 0.7 |
| `T`    | `eg_type[0]` | `eg0_type` | uint 0-3 | Type for Envelope Generator 0 - 0: Normal (RC-like) / 1: Linear / 2: DX7-style / 3: True exponential. |
| `X`    | `eg_type[1]` | `eg1_type` | uint 0-3 | Type for Envelope Generator 1 - 0: Normal (RC-like) / 1: Linear / 2: DX7-style / 3: True exponential. |
| `y`    | `bus`      | `bus` | int   | Bus that this osc gets added onto (default 0) |
| `l`    | `velocity` | `vel` | float | Note on velocity. Use to start an envelope or set amplitude |

### CtrlCoefs

These per-oscillator parameters use [CtrlCoefs](synth.md) notation

| Wire code   | C `amy_event` | Python / JS   | Type-range  | Notes                                 |
| ------ | -------- | ---------- | ----------  | ------------------------------------- |
| `Q`    | `pan_coefs[]` | `pan`   | float[,float...] | Panning index ControlCoefficients (for stereo output), 0.0=left, 1.0=right. default 0.5. |
| `a`    | `amp_coefs[]` | `amp`    | float[,float...]  | Control the amplitude of a note; a set of ControlCoefficients. Default is 1,0,1,1  (i.e. an overall gain of 1, scaled by the note velocity and Envelope Generator 0.) The first (`const`) coefficient is an overall gain: setting it to 0 mutes the oscillator entirely. Coefficients are combined in the log (dB) domain — see [synth.md](synth.md#control-coefficients). |
| `d`    | `duty_coefs[]` | `duty`   |  float[,float...] | Duty cycle for pulse wave, ControlCoefficients, defaults to 0.5 |
| `f`    | `freq_coefs[]` | `freq`   |  float[,float...]      | Frequency of oscillator, set of ControlCoefficients.  Default is 0,1,0,0,0,0,1 (from `note` pitch plus `pitch_bend`) |
| `F`    | `filter_freq_coefs[]` | `filter_freq` | float[,float...]  | Center/break frequency for variable filter, set of ControlCoefficients |

### PCM sampling

| Wire code   | C `amy_event` | Python / JS   | Type-range  | Notes                                 |
| ------ | -------- | ---------- | ----------  | ------------------------------------- |
| `z`    | **TODO**| `load_sample` | uint x 6 | Signal to start loading sample. preset number, length(frames), samplerate, channels, midinote, loopstart, loopend. All subsequent messages are base64 encoded WAVE-style frames of audio until `length` is reached. Set `preset` and `length=0` to unload a sample from RAM. |
| `zF`   | **TODO**| `disk_sample` | uint,string,uint | Set a PCM preset to play live from a WAV filename on AMY host disk. Params: preset number, filename, midinote. See `hooks` for reading files on host disk. **Only one file sample can be played at once per preset number. Use multiple presets if you want polyphony from a single sample.** |
| `zS`   | **TODO**| `start_sample` | uint x 6 | Start sampling to a stereo PCM preset from source. Params: preset number, source, max length in frames, midinote, loopstart, loopend. source = 1 is AMY mixed output. source = 2 is AUDIO_IN0 + 1.  Will sample until max length is reached, `stop_sample` is issued, or a new `start_sample` is issued. | 
| `zO`   | **TODO**| `stop_sample` | uint | Stop sampling. Does nothing if no sampling active. param ignored. | 

### WAVETABLE wave type

`wave=WAVETABLE` is available when AMY is built with `-DAMY_WAVETABLE`.

- Wavetable samples are baked into `pcm_tiny` and exposed as contiguous PCM presets.
- The preset range is dynamic at runtime:
  - start: `pcm_wavetable_base`
  - count: `pcm_wavetable_samples`
  - valid presets: `pcm_wavetable_base ... pcm_wavetable_base + pcm_wavetable_samples - 1`
- Each wavetable preset is expected to be one 64-cycle table (normally `16384` samples total, `256` samples per cycle).
- `duty` crossfades across the 64 cycles inside the selected wavetable preset.

### Drum kits (GAMMA9001 builds)

Devices built with `-DGAMMA9001` (Tulip, AMYboard, AMY on the web) carry the Gamma9001 drum sample banks: the full TR-808 bank is baked in as PCM presets 0-18, and 136 more samples (TR-909, Linn 9000, Univox MR-12, Tokyo Synthetics, 80s Power Kit, Percussion) live at presets 256-391, served from a platform-provided blob (linked into the wasm on web; an mmapped `drums` flash partition on ESP32-S3). All of them play directly with `wave=PCM, preset=P`.

Patches **384-390** are ready-made General MIDI drum kits over these banks -- load one on a synth with `synth_flags=3` and GM note numbers trigger the mapped samples:

| patch | MIDI PC (bank MSB 3) | kit |
|-------|----------------------|-----|
| 384 | 0 | TR-808 (baked; works without the sample banks mounted) |
| 385 | 1 | TR-909 |
| 386 | 2 | Linn 9000 |
| 387 | 3 | Univox Micro Rythmer 12 |
| 388 | 4 | Tokyo Synthetics |
| 389 | 5 | 80s Power Kit |
| 390 | 6 | Percussion |

Switch kits with `amy.send(synth=10, patch=38x)`, or over MIDI with bank select MSB 3 (CC0=3) + program change 0-6 on the drum channel; a synth already on a kit patch stays in the kit bank, so a bare program change also switches kits. Channel 10 defaults to the TR-808 kit when default synths are enabled. Non-GAMMA9001 builds keep the legacy 11-sample kit at patch 258. Patches 259-383 are reserved.

### Per-bus Effects

Each of the `y` buses has separate effects units.  You set their parameters with commands such as `amy.send(bus=0, reverb=1)` (or `y0h1`).

The final mixdown of the buses onto the AMY output is controlled by one value per bus passed to the `volume` (`V`) command.

Default AMY has 4 buses, 0..3.  If the bus (`y`) is not specified for one of these commands, it defaults to 0.

| Wire code   | C `amy_event` | Python / JS   | Type-range  | Notes                                 |
| ------ | -------- | ---------- | ----------  | ------------------------------------- |
| `h`    | `reverb_level, reverb_liveness, reverb_damping, reverb_xover_hz` | `reverb` | float[,float,float,float] | Reverb parameters -- level, liveness, damping, xover: Level is for output mix;
| `k`    | `chorus_level, chorus_max_delay, chorus_lfo_freq, chorus_depth` | `chorus` | float[,float,float,float] | Chorus parameters -- level, delay, freq, depth: Level is for output mix (0 to turn off); delay is max in samples (320); freq is LFO rate in Hz (0.5); depth is proportion of max delay (0.5). |
| `M`    | `echo_level, echo_delay_ms, echo_max_delay_ms, echo_feedback, echo_filter_coef` | `echo` | float[,int,int,float,float] | Echo parameters --  level, delay_ms, max_delay_ms, feedback, filter_coef (-1 is HPF, 0 is flat, +1 is LPF). |
| `x`    | `eq_l, eq_m, eq_h` |`eq` | float,float,float | Equalization in dB low (~800Hz) / med (~2500Hz) / high (~7500Hz) -15 to 15. 0 is off. default 0. |

### Other

| Wire code   | C `amy_event` | Python / JS   | Type-range  | Notes                                 |
| ------ | -------- | ---------- | ----------  | ------------------------------------- |
| `H`    | `sequence[3]` | `sequence` | int,int,int | Tick offset, period, tag for sequencing | 
| `j`    | `tempo` | `tempo`  | float | The tempo (BPM, quarter notes) of the sequencer. Defaults to 108.0. |
| `N`    | `latency_ms`| `latency_ms` | uint | Sets latency in ms. default 0 (see LATENCY) |
| `s`    | `pitch_bend` | `pitch_bend` | float | Sets the global pitch bend, by default modifying all note frequencies by (fractional) octaves up or down |
| `t`    | `time` | `time` | uint | Request playback time relative to some fixed start point on your host, in ms. Allows precise future scheduling. |
| `V`    | `volume`| `volume` | float, float, ...  | Volume knob for each bus in the final mixdown, default 1.0 |
| `g`    | `client` | `client` | uint | Client number for Alles distributed synthesis. |
| `W`    | `external_channel` | `external_channel` | uint | External channel routing (used by Tulip for CV output). |
| `D`    | **TODO** | `debug`  |  uint, 2-4  | 2 shows queue sample, 3 shows oscillator data, 4 shows modified oscillator. Will interrupt audio! |
| `zT`   | **TODO**| `transfer_file` | string,uint | Transfer a file to the host. Params: destination filename, file size. See `hooks` for writing files on host disk. |
| `zA`   | **TODO**| `update_file` | string (optional) | Update a file on disk with current AMY state via `update_file_hook`. Default path: `/user/current/sketch.py`. On AMYboard, splices `_auto_generated_knobs` section with live state. The filename is "rest of message": a trailing `Z` end-of-message marker is stripped, so interior capital-`Z` characters (e.g. `/user/ZFILE.py`) are preserved. Filenames whose last character is `Z` are not addressable. |
| `zD`   | **TODO**| `dump_sysex` | string (optional) | Dump data over MIDI sysex (base64-encoded, wrapped with SPSS manufacturer ID `00 03 45`). With no params (`zDZ`): dumps all active instrument state. With a filename (`zD/user/current/sketch.pyZ`): reads file and sends it. The filename is "rest of message": a trailing `Z` end-of-message marker is stripped, so interior capital-`Z` characters (e.g. `/user/ZFILE.py`) are preserved. Filenames whose last character is `Z` are not addressable. |
| `zP`   | **TODO**| `exec` | string | Execute code on the host via `amy_external_exec_hook`. On AMYboard, runs the string as Python (e.g. `zPimport amyboard; amyboard.restart_sketch()`). Max 255 chars. The code string is "rest of message": a trailing `Z` end-of-message marker is stripped, so interior capital-`Z` characters in the code are preserved. Code whose last character is `Z` is not expressible. |
| `zI`   | **TODO**| `ping` | (none) | Ping the host. Replies with a short sysex frame `F0 00 03 45 'O' 'K' F7` so the caller can confirm the board is alive and sysex is flowing. Handled entirely in pure C (no scheduler needed). |
| `zB`   | **TODO**| `reboot` | uint (optional) | Reboot the host via `amy_external_reboot_hook`. Optional `mode` argument selects the post-reboot state: `zBZ` / `zB0Z` = bootloader mode (skip sketch on next boot), `zB1Z` = normal reboot (run sketch), `zB2Z` = ROM download / flash mode. Handled in pure C (no scheduler needed). On AMYboard, sets an RTC flag with the mode and calls `esp_restart()`. |
