21 PWM audio
21 : PWM audio
- Author: Yeo Kheng Meng
- Description: Takes in 8-bit audio over a parallel (port) interface then generates an analog audio signal like a Covox Speech Thing.
- GitHub repository
- Open in 3D viewer
- Clock: 10000000 Hz
- Feedback: ✅ 1
How it works
This is meant as a parallel port sound card like a Covox Speech Thing. Instead of R-2R resistors, the chip will generate the analog audio output using PWM and First-order sigma-delta modulator.
How to test
No particular test required.
External hardware
A 0.1uF capacitor to ground is recommended on the 2 audio output pins
IO
| # | Input | Output | Bidirectional |
|---|---|---|---|
| 0 | Bit 0 of Parallel port (LSB) | Standard PWM audio output | Direct from input 0 |
| 1 | Bit 1 of Parallel port | Sigma-delta modulator output | Direct from input 1 |
| 2 | Bit 2 of Parallel port | From ena pin | Direct from input 2 |
| 3 | Bit 3 of Parallel port | From clk pin | Direct from input 3 |
| 4 | Bit 4 of Parallel port | From rst_n pin | Direct from input 4 |
| 5 | Bit 5 of Parallel port | Static 1 | Direct from input 5 |
| 6 | Bit 6 of Parallel port | Static 0 | Direct from input 6 |
| 7 | Bit 7 of Parallel port (MSB) | Static 1 | Direct from input 7 |
User feedback
- yeokm1👑: It is extremely satisfying to have my design baked into physical hardware and working as expected. No flashing of microcontroller firmware, computer software or FPGA bitstream. Just fixed electronic circuits doing your bidding. I have certainly gained a better appreciation of the chip design process. Link for more details