Hi,
I have a question about the Audio Linein on GPIO1 (I use A20-OLinuXino-MICRO-4GB).
How should I connect this to a Line out? Is it necaserry to add protection (capacitor? or other circuit)
I couldn't find any info also not in the A20 datasheet/manual.
I did some test with the MAX9814 microphone amplifier (https://learn.adafruit.com/adafruit-agc-electret-microphone-amplifier-max9814/overview) It works fine but after a while it doesn't.
Regards, Joost
I'm also interested in using the Line-in, hopefully somebody will have information for us :)
It depens of voltage levels of the signal source, but probably all circuitry you will need is a voltage divider (see http://en.wikipedia.org/wiki/Voltage_divider (http://en.wikipedia.org/wiki/Voltage_divider)) made of two resistors or one trimmer (or potentiometer, preferably logarithmic) per channel to adjust voltage. Capacitors are already there.
The 2 Vpp (peak-to-peak) are probably too much, so you should use at least 1:2 division (eg. two identical resistors, in tens of kiloohms range).