256 Wavetable Sound Generator
256 : Wavetable Sound Generator
- Author: Ryota Suzuki
- Description: Small wavetable/PSG type sound generator with I2S output
- GitHub repository
- Clock: 50000000 Hz
How it works
This project is Small wave table/PSG type sound generator with I2S output. Major features are:
- 4 channel sound generator
- 4-bit x 32depth wave table (can be uses as 2 of 16depth wave table)
- 8 selectable waveform (3x pulse,1x noise, 4x wave table)
- 8-bit volume(only for PSG mode, wave table mode is 4-step volume)
- 16-bit frequency
- Sampling Frequency is 48828.125Hz (at 50MHz clock)
- I2S output (16-bit mono)
- SPI control interface
You can control this sound generator by SPI interface. SPI mode is mode 0 (CPOL=0, CPHA=0), and transaction length is 24-bit. first 8-bit is register address, and next 16-bit is data. Data is MSB first.
| Addr | Description | Width |
|---|---|---|
| 0x00-0x03 | Frequency[0]-[3] | 16bit |
| 0x04-0x07 | Volume[0]-[3] | 8bit (lower 8bits are valid) |
| 0x08-0x0b | Waveform Select[0]-[3] | 3bit (lower 3bits are valid) |
| 0x20-0x3f | WaveTable[0]-[31] | 4bit (lower 4bits are valid) |
How to test
Connect I2S output to I2S DAC, and control this sound generator by SPI interface. SPI input is connected to RP2040's SPI1 on TT05 breakout board.
External hardware
I2S DAC is required (I tested this design with FPGA and PCM5102A DAC)
IO
| # | Input | Output | Bidirectional |
|---|---|---|---|
| 0 | SPI CS Input | I2S Bit Clock | |
| 1 | SPI CLK Input | I2S Word Select | |
| 2 | SPI MOSI Input | I2S Data | |
| 3 | |||
| 4 | |||
| 5 | |||
| 6 | |||
| 7 |