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
  • GDS submitted
  • HDL project
  • Extra docs
  • Clock: 10000000 Hz
  • External hardware: A 0.1uF capacitor to ground is recommended on the 2 audio output pins

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.


# 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