View Full Version : Audio Adapter's Aux port as an Input

08-20-2016, 08:57 PM
Hey, I think the answer to this question will be really simple but I've been trying to figure it out for a while now. I'd like to plug an aux cable into the jack on the audio adapter and have that as a way to input audio for FFT. In the code, whenever I choose "line in" as the input, it is referring to the holes on the other side of the board. How in the world do I use this aux jack as an input? Thanks for the help!

PS. 1st post! Hopefully with many more to come. The project I've been working on (a good 'ol LED strip reacting to music) finally got too big for the Arduino so I've made the jump to Teensy. :cool:

08-20-2016, 10:11 PM
The TRS-Jack is really only a headphone output, it cannot be used as an input. The line-in ("aux input") is only available at the solder pads you mentioned.

08-21-2016, 12:10 AM
Ah, that explains it. You think it's possible / a good idea to solder wires from the contacts on the aux jack over top of the board to the line in solder pads? It's either I do that or I just bought some separate aux jacks that I can do that with.

08-21-2016, 12:24 AM
You could, in theory, do that. But you'd also have to cut three traces on the adaptor board to disconnect the jack from the headphone output pins on the SGTL5000 IC.

A better solution is to use the fact that the pin arrangement of the solder pads is intentionally the same as on any PC mainboard, so you can use these kind of adaptors: https://www.amazon.com/Computer-Front-Panel-Audio-Earphone/dp/B00B2ZAPHA/ref=sr_1_2?ie=UTF8&qid=1471735018&sr=8-2&keywords=front+audio+cable.
I only did a quick search to get you a link and didn't find any adaptors without the USB part, but I'm sure you can see what I'm referring to. If you want to use one of these adaptors you'd solder male header pins to the audio board.

This latter solution is the "official" way to connect a TRS-jack to the line in. It also leaves the headphone jack intact, which is nice to have if you ever want to re-purpose the board in another project.

Edit: Soldering any other aux jacks to the solder pads is of course also a viable solution!

08-21-2016, 12:51 AM
Thanks Ben! That helps a lot and I found a cable with audio only. Link for anyone interested (https://www.amazon.com/Dell-Vostro-460-470-Front/dp/B00LCA5PZC/ref=sr_1_7?ie=UTF8&qid=1471736703&sr=8-7)

I think for now I'll stick with the extra aux jack I have since I'm just building a prototype. That's all good to know though!