rpi4-osdev/part9-sound/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](https://github.com/PeterLemon/RaspberryPi/tree/master/Sound/PWM/8BIT/44100Hz/Stereo/CPU), 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)
First commit of part9-sound code 2021-02-17 10:32:35 +00:00			`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](https://github.com/PeterLemon/RaspberryPi/tree/master/Sound/PWM/8BIT/44100Hz/Stereo/CPU), 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.
PWM audio now works using either CPU or DMA in part9-sound demo 2021-02-17 23:40:03 +00:00			* Write-up the DMA version `playaudio_dma()` version, which doesn't tie up the CPU but still plays sound!
First commit of part9-sound code 2021-02-17 10:32:35 +00:00			`* Add a Makefile.gcc (I'm using LLVM Clang these days, so not a priority)`