Android Question Data over headphone jack

[scarr]

Hi all,

Does anyone know if any code / library exists for this? so we can use it with B4A

http://www.lpcware.com/content/project/smartphone-quick-jack-solution

It's a neat little data over headphone jack device.

Steve.

 

[joedarock]

Has any work been done to send/receive low-rate data over the headphone jack?

Joe

 

[JordiCP]

I bought the NXP Quick-jack board some time ago and played with it (with the android demo). They also provide the Android source code (not very clean, but understandable) so that it can be tuned. It can be a good starting point to experiment. It's quite cheap
http://uk.farnell.com/nxp/om13069/demo-board-smartphone-quick-jack/dp/2427497

From my experience, it works "more or less" but depends on the device, as the audio circuit output impedance and current capability may vary between devices, specially if you want to feed your board from the same audio signal (really small power, as it's intended for other purposes) without any battery backup.

Important to take into consideration if you only want to communicate only from device to board, board to device, or both. Also, that the board must be really low-power and/or battery-powered.