Stage Two Complete!

"Future Heap Owner" (aperiodic) 05/04/2019 at 13:14 • Filed to: Project RAUX Box, Electronics, Audio

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After verifying my I2C communication primitives, programming the audio chip to convert an AUX signal into the stereo’s internal format was a matter of plug & chugging through the data sheet. That means I’ve finished stage two of !!!error: Indecipherable SUB-paragraph formatting!!! !

The image above is logic analyzer output I captured last night showing noisy I2S signals from the chip. I’m pretty sure the noise is because I had to leave them “floating”, meaning they’re unconnected and there’s nothing pulling them to ground or 3.3 volts; when they go into the I2S receiver in the stereo’s DAP I’m confident completing the circuit will remove the noise . From what I’ve read, you don’t put pull-up resistors or anything on an I2S connection like you do with the I2C bus. I tried anyways and it only swamped the signal: the lines were either always at ground or almost entirely at 3.3V.

Getting this done last night means I’m on schedule so far. Next I’m moving from the development phase to prepping for installation. Today I hope to turn this breadboard circuit into something slightly less janky on protoboards with real solder joins for the connections , and add two relays for the I2S switching. It’s probably around a couple hours of diagramming and soldering, which I should be able to finish today with any luck.

I think installation will be pretty straightforward, in part because I’ve popped the stereo out before. After it’s out I just need to take some of the shielding off, locate a huge ribbon cable, cut the leftmost three wires, make six or nine solder joins, then test & debug.

I might actually finish this in time for the cruise! Fingers crossed. I think it will mostly depend on how much debugging I need to do post-installation.

vondon302 > Future Heap Owner 05/04/2019 at 13:31

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This is so far over my head it might as well be written in another language that I only know a few words of.

All this for a aux port wow.

Future Heap Owner > vondon302 05/04/2019 at 13:36

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Yeah, for the same reason I have to do all this nonsense , an aftermarket AUX port is $300, and I’m a cheap bastard.

vondon302 > Future Heap Owner 05/04/2019 at 14:17

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Lol. If ya got the skills why not.

300 hundy is 300 hundy

DipodomysDeserti > Future Heap Owner 05/04/2019 at 14:55

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I have AUX inputs on two vehicles made this decade, and both pick ups have already eaten shit. You’d probably be better off with one of those old school $5 tapedeck AUX deals. They even make Bluetooth ones now.

Future Heap Owner > DipodomysDeserti 05/04/2019 at 15:23

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I wish my car had a tape deck! CD player & radio only. Before you suggest it,  I don’t want to deal with the fuzz & hassle of an FM transmitter.

DipodomysDeserti > Future Heap Owner 05/04/2019 at 16:45

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A CD player, but no AUX. Fucking Swedes.

Future Heap Owner > DipodomysDeserti 05/04/2019 at 17:04

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CDs are the future bro!