Building on top of Rouslan Dimitrov's Microcontroller Class D Amplifier, I developed the idea to feed the power amplifier with PCM data directly. Rouslan does some dithering and noise shaping, but I'm convinced that proper interpolation would sound better. The ATtiny is too slow to do even cubic interpolation so I'll move that into the host.

The result should be an ALSA driver, that does upsampling of 44.1 or 48 kHz to about 240 kHz (the Class-D PWM frequency) and sends it over preferably, but not limited to, SPI towards the AVR, which will drive the power FETs with its PWM outputs. This can give any (embedded) linux system the right audio "punch" with a fairly short BOM.

Looking for hackers with the skills:

alsa arm arduino kernel mips hardware

This project is part of:

Hack Week 10

Activity

  • over 11 years ago: duwe added keyword "hardware" to this project.
  • over 11 years ago: duwe added keyword "mips" to this project.
  • over 11 years ago: duwe added keyword "kernel" to this project.
  • over 11 years ago: cyberiad liked this project.
  • over 11 years ago: duwe liked this project.
  • over 11 years ago: duwe added keyword "alsa" to this project.
  • over 11 years ago: duwe added keyword "arm" to this project.
  • over 11 years ago: duwe added keyword "arduino" to this project.
  • over 11 years ago: duwe started this project.
  • over 11 years ago: duwe originated this project.

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    Project Description

    When we experience a early boot crash, we are not able to analyze the kernel dump, as user-space wasn't able to load the crash system. The idea is to make the crash system compiled into the host kernel (think of initramfs) so that we can create a kernel dump really early in the boot process.

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    1. Investigate if this is possible and the implications it would have (done in HW21)
    2. Hack up a PoC (done in HW22 and HW23)
    3. Prepare RFC series (giving it's only one week, we are entering wishful thinking territory here).

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      • fix problem of memdup not being able to alloc so much memory... use 64K page sizes for now
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      • hacking arch/arm64/kernel/crash_dump.c:copy_old_mempage() to see if crash system really starts. It does.
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