mirror of
https://github.com/exoticorn/microw8.git
synced 2026-01-20 19:26:43 +01:00
add first version of sound doku
This commit is contained in:
@@ -234,7 +234,8 @@ Avoid the reserved control chars, they are currently NOPs but their behavior can
|
||||
| 2-3 | - | Reserved |
|
||||
| 4 | - | Switch to normal mode |
|
||||
| 5 | - | Switch to graphics mode |
|
||||
| 6-7 | - | Reserved |
|
||||
| 6 | - | Reserved |
|
||||
| 7 | - | Bell / trigger sound channel 0 |
|
||||
| 8 | - | Move cursor left |
|
||||
| 9 | - | Move cursor right |
|
||||
| 10 | - | Move cursor down |
|
||||
@@ -276,34 +277,120 @@ Sets the cursor position. In normal mode `x` and `y` are multiplied by 8 to get
|
||||
|
||||
## Sound
|
||||
|
||||
### Low level operation
|
||||
|
||||
MicroW8 actually runs two instances of your module. On the first instance, it calls `upd` and displays the framebuffer found in its memory. On the
|
||||
second instance, it calls `snd` instead with an incrementing sample index and expects that function to return sound samples for the left and right
|
||||
channel at 44100 Hz. If your module does not export a `snd` function, it calls the api function `sndGes` instead.
|
||||
|
||||
As the only means of communication, 32 bytes starting at address 0x00050 are copied from main to sound memory after `upd` returns. At the same time,
|
||||
32 bytes starting at 0x12c80 are copied from sound to main memory.
|
||||
|
||||
By default, the `sndGes` function generates sound based on the 32 bytes at 0x00050. This means that in the default configuration those 32 bytes act
|
||||
as sound registers. See the `sndGes` function for the meaning of those registers.
|
||||
|
||||
### fn playNote(channel: i32, note: i32)
|
||||
|
||||
Triggers a note (1-127) on the given channel (0-3). Notes are semitones with 69 being A4 (same as MIDI). A note value of 0 stops the
|
||||
sound playing on that channel. A note value 128-255 will trigger note-128 and immediately stop it (playing attack+release parts of envelope).
|
||||
|
||||
This function assumes the default setup, with the `sndGes` registers located at 0x00050.
|
||||
|
||||
### fn sndGes(sampleIndex: i32) -> f32
|
||||
|
||||
This implements a sound chip, generating sound based on 32 bytes of sound registers.
|
||||
|
||||
The spec of this sound chip are:
|
||||
|
||||
- 4 channels
|
||||
- rect, saw, tri, noise wave forms selectable per channel
|
||||
- each wave form supports some kind of pulse width modulation
|
||||
- each channel has an optional automatic low pass filter, or can be sent to one of two manually controllable filters
|
||||
- each channel can select between a narrow and a wide stereo positioning. The two stereo positions of each channel are fixed.
|
||||
|
||||
This function requires 1024 bytes of working memory, the first 32 bytes of which are interpreted as the sound registers.
|
||||
The base address of its working memory can be configured by writing the address to 0x12c78. It defaults to 0x00050.
|
||||
|
||||
Here is a short description of the 32 sound registers.
|
||||
|
||||
```
|
||||
Per channel:
|
||||
00 - CTRL0
|
||||
06 - CTRL1
|
||||
0c - CTRL2
|
||||
12 - CTRL3
|
||||
| 7 6 | 5 | 4 | 3 2 | 1 | 0 |
|
||||
| wave | ring | wide | filter | trigger | note on |
|
||||
|
||||
00 : CTRL - wave form, ring, sync, filter send, trigger
|
||||
bit 0: note on flag
|
||||
bit 1: note trigger
|
||||
bit 2,3: filter 0,1 send
|
||||
bit 6,7: wave form (rect, saw, tri, noise)
|
||||
01 : PULS - pulse width
|
||||
02 : FINE - fine tuning
|
||||
03 : NOTE - note
|
||||
04 : ENVA - attack, decay
|
||||
05 : ENVR - sustain, release
|
||||
note on: stay in decay/sustain part of envelope
|
||||
trigger: the attack part of the envlope is triggered when either this changes
|
||||
or note on is changed from 0 to 1.
|
||||
filter : 0 - no filter
|
||||
1 - fixed 6db 1-pole filter with cutoff two octaves above note
|
||||
2 - programmable filter 0
|
||||
3 - programmable filter 1
|
||||
wide : use wide stereo panning
|
||||
ring : ring modulate with triangle wave at frequency of previous channel
|
||||
wave : 0 - rectangle
|
||||
1 - saw
|
||||
2 - triangle
|
||||
3 - noise
|
||||
|
||||
50-56: channel 0
|
||||
56-5b: channel 1
|
||||
5c-61: channel 2
|
||||
62-67: channel 3
|
||||
01 - PULS0
|
||||
07 - PULS1
|
||||
0d - PULS2
|
||||
13 - PULS3
|
||||
Pulse width 0-255, with 0 being the plain version of each wave form.
|
||||
rectangle - 50%-100% pulse width
|
||||
saw - inverts 0%-100% of the saw wave form around the center
|
||||
triangle - morphs into an octave up triangle wave
|
||||
noise - blends into a decimated saw wave (just try it out)
|
||||
|
||||
68: VO01 - volumes channel 0&1
|
||||
69: VO23 - volumes channel 2&3
|
||||
02 - FINE0
|
||||
08 - FINE1
|
||||
0e - FINE2
|
||||
14 - FINE3
|
||||
Fractional note
|
||||
|
||||
6a : FCTR 0 - type, resonance
|
||||
6b : FCTR 1 - type, resonance
|
||||
6c : FFIN 0 - cutoff fine tuning
|
||||
6d : FNOT 0 - cutoff note
|
||||
6e : FFIN 1 - cutoff fine tuning
|
||||
6f : FNOT 1 - cutoff note
|
||||
03 - NOTE0
|
||||
09 - NOTE1
|
||||
0f - NOTE2
|
||||
15 - NOTE3
|
||||
Note, 69 = A4
|
||||
|
||||
04 - ENVA0
|
||||
0a - ENVA1
|
||||
10 - ENVA2
|
||||
16 - ENVA3
|
||||
| 7 6 5 4 | 3 2 1 0 |
|
||||
| decay | attack |
|
||||
|
||||
05 - ENVB0
|
||||
0b - ENVB1
|
||||
11 - ENVB2
|
||||
17 - ENVB3
|
||||
| 7 6 5 4 | 3 2 1 0 |
|
||||
| release | sustain |
|
||||
|
||||
18 - VO01
|
||||
| 7 6 5 4 | 3 2 1 0 |
|
||||
| volume 1 | volume 0 |
|
||||
|
||||
19 - VO23
|
||||
| 7 6 5 4 | 3 2 1 0 |
|
||||
| volume 3 | volume 2 |
|
||||
|
||||
1a - FCTR0
|
||||
1b - FCTR1
|
||||
| 7 6 5 4 | 3 | 2 | 1 | 0 |
|
||||
| resonance | 0 | band | high | low |
|
||||
|
||||
1c - FFIN0
|
||||
1e - FFIN1
|
||||
cutoff frequency - fractional note
|
||||
|
||||
1d - FNOT0
|
||||
1f - FNOT1
|
||||
cutoff frequency - note
|
||||
```
|
||||
|
||||
# The `uw8` tool
|
||||
|
||||
Reference in New Issue
Block a user