mirror of
https://github.com/tildearrow/furnace.git
synced 2024-11-18 10:35:11 +00:00
28 lines
1.3 KiB
Markdown
28 lines
1.3 KiB
Markdown
# Atari Lynx instrument editor
|
|
|
|
Atari Lynx instrument editor consists of these macros:
|
|
|
|
- **Volume**: volume sequence
|
|
- **Arpeggio**: pitch in half-steps
|
|
- **Duty/Int**: bit pattern for LFSR taps and integration
|
|
- **Panning (left)**: output level for left channel
|
|
- **Panning (right)**: output level for right channel
|
|
- **Pitch**: fine pitch
|
|
- **Phase Reset**: trigger restart of waveform
|
|
|
|
## Audio generation description
|
|
|
|
Atari Lynx generates sound using a 12-bit linear feedback shift register with configurable tap. Nine separate bits can be enabled to be the source of feedback: 0, 1, 2, 3, 4, 5, 7, 10 and 11. To generate _any_ sound at least one bit _must_ be enabled.
|
|
|
|
### Square wave
|
|
|
|
The LFSR is shifted at the rate define by sound pitch and generates square wave by setting channel output value to +volume or -volume, depending on the bit shifted in.
|
|
|
|
### Triangle wave
|
|
|
|
Alternatively when "int" bit is set sound wave is generated by adding or subtracting volume from output effectively producing triangle wave.
|
|
|
|
#### How triangle wave works?
|
|
|
|
Hint: To obtain triangle set bits "int" and "11" in "Duty/Int" sequence and set volume to about 22.
|
|
By enabling 11th tap bit the value shifted in is negated after 11 bit is shifted in hence the volume is added for 11 cycles and then subtracted for 11 cycles.
|