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History

Adam Greenwood-Byrne 4386a4ca32 PWM audio now works using either CPU or DMA in part9-sound demo		2021-02-17 23:40:03 +00:00
..
audio.bin	First commit of part9-sound code	2021-02-17 10:32:35 +00:00
audio.wav	First commit of part9-sound code	2021-02-17 10:32:35 +00:00
boot.S	First commit of part9-sound code	2021-02-17 10:32:35 +00:00
fb.c	First commit of part9-sound code	2021-02-17 10:32:35 +00:00
fb.h	First commit of part9-sound code	2021-02-17 10:32:35 +00:00
io.c	First commit of part9-sound code	2021-02-17 10:32:35 +00:00
io.h	PWM audio now works using either CPU or DMA in part9-sound demo	2021-02-17 23:40:03 +00:00
kernel.c	PWM audio now works using either CPU or DMA in part9-sound demo	2021-02-17 23:40:03 +00:00
link.ld	First commit of part9-sound code	2021-02-17 10:32:35 +00:00
Makefile	First commit of part9-sound code	2021-02-17 10:32:35 +00:00
mb.c	First commit of part9-sound code	2021-02-17 10:32:35 +00:00
mb.h	First commit of part9-sound code	2021-02-17 10:32:35 +00:00
README.md	PWM audio now works using either CPU or DMA in part9-sound demo	2021-02-17 23:40:03 +00:00
terminal.h	First commit of part9-sound code	2021-02-17 10:32:35 +00:00

README.md

Writing a "bare metal" operating system for Raspberry Pi 4 (Part 9)

Playing sound from the audio jack

One thing our game is missing is the excitement of sound! Some beeps and squeaks would be a wonderful addition to make the gameplay more compelling. Let's work to do just that!

This code was derived from Peter Lemon's work, for which I am very grateful. It's been ported to C with some modifications to work on the Raspberry Pi 4 hardware.

Todo

Write-up the CPU-driven playaudio_cpu() code, explaining clocks/PWM etc.
Write-up the DMA version playaudio_dma() version, which doesn't tie up the CPU but still plays sound!
Add a Makefile.gcc (I'm using LLVM Clang these days, so not a priority)