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Project RAUX Box: Stage One Complete!

The first stage of Project RAUX Box was simply to get my development toolchain set up, because I haven’t done any serious embedded programming for five or so years. As you can see from the GIF, I’ve done it! You can tell because the blink pattern is not the typical one second on, one second off.

Yes, blinking an LED counts as victory in computerland. Don’t do computers, kids!

I use the Arduino/AVR toolchain, but I prefer to do it outside of the official Arduino IDE because I need mah vim. As I expected, there have been changes to the official IDE’s internals that necessitated finding a new Makefile to do the compiling & uploading, but those changes happened a while ago so that wasn’t hard. The only tricky bit was figuring out exactly which board & bootloader settings I needed to choose for my cheap knockoff board. But all in all it was well under half an hour to get that sweet, sweet LED blinkage.

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Now I can move on to a more interesting part: encoding the analog signal to digital using this here audio processing breakout board:

That’ll look roughly like this:

  • Solder some header pins to the Arduino clone and breakout board
  • Connect the two pins for the I2C control channel between the two boards, either on a breadboard or using jumper wires (and put in VCC/GND for the audio board)
  • Spend some quality time with the audio processing chip’s datasheet.
  • Write some code to configure the audio processing chip to do nothing but encode the analog in to digital, in right-justified 16-bit I2S format (bypassing the signal processing functionality of the chip).
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The problem with this plan is that I don’t have a good way to test it out at the end. I do have a Salae logic analyzer, but I’m not sure whether it supports I2S. If it doesn’t, then I gotta go find someone who’ll let me use their oscilloscope (I don’t do this sort of thing enough to justify buying an oscilloscope).

I hope to make progress on Stage Two this weekend. Stay tuned.

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