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| author | John "Lameguy" Wilbert Villamor <lameguy64@gmail.com> | 2022-11-03 10:14:22 +0800 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2022-11-03 10:14:22 +0800 |
| commit | 4139331d233b7a962e747c5564fa68a285f81cc8 (patch) | |
| tree | d4d3374afd5e36e8580cc424ab2c63ee9e7d357c /doc/dev_notes.md | |
| parent | e08a3d9366f8ca14a76b3dd569dac1fb9f569748 (diff) | |
| parent | 37d963f724113e45d15aa9b8ee86baa9c4362b8f (diff) | |
| download | psn00bsdk-4139331d233b7a962e747c5564fa68a285f81cc8.tar.gz | |
Merge pull request #60 from spicyjpeg/bugfix
Bugfixes, new serial port API and sound examples
Diffstat (limited to 'doc/dev_notes.md')
| -rw-r--r-- | doc/dev_notes.md | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/doc/dev_notes.md b/doc/dev_notes.md index 3c3aa55..fa01756 100644 --- a/doc/dev_notes.md +++ b/doc/dev_notes.md @@ -135,13 +135,19 @@ _- spicyjpeg_ 4. If no valid response is received, assume no controller is connected and reset the port's digital-only flag. -- I haven't worked on `psxspu` but, for those willing to write some code, this - is the formula to calculate SPU pitch values for playing musical notes (`^` - is the power operator, not xor): +- The SPU *really* doesn't like 32-bit register writes. It is connected to the + CPU through a 16-bit bus; 32-bit writes are automatically split into two + transactions, however the SPU has a tendency to miss one of them (perhaps due + to the bus controller issuing them too quickly). This might be why nocash + docs claim that writing to the SPU is unstable when in actual fact 16-bit + writes seem to be perfectly stable. + +- This is the formula to calculate SPU pitch values for playing musical notes + (`^` is the power operator, not xor): ``` frequency = (ref / 32) * (2 ^ ((note - 9) / 12)) - spu_pitch = frequency / 44100 * 4096 + spu_pitch = (frequency * 4096) / 44100 ref = frequency the sample should be played at to play a middle A (MIDI note 69) note = MIDI note number (usually 0-127, 60 is middle C) @@ -280,4 +286,4 @@ _- spicyjpeg_ space. ----------------------------------------- -_Last updated on 2022-03-25 by lameguy64_ +_Last updated on 2022-10-30 by spicyjpeg_ |