I would like to investigate the possibility of using an Arduino device to develop a cable which uses the headphone jack of an android device as an input, converts to digital and outputs to the device again via usb link.
Is Arduino the right way to go about this? If so any pointers to similar projects would be of great help.
I am currently developing android apps and have previously worked as a embedded engineer, however I feel I am a bit out of the loop on android accessory dev.
thanks for any help, it will be greatly appreciated.
ADC? What quality are you looking for, the standard Arduino only does 10 bit and is fast enough for voice but can be pushed a bit faster.
Also for USB interfacing you'd need a separate module or the newer Due (which I think as 12bit ADC).
The triggertrap shutter release (http://www.triggertrap.com) uses the phone jack for their Android and IOS products. They discovered that they had to re-engineer the dongle that sits in the 3.5mm jack and connects to the camera specific 2.5mm cable because phones sold in the European union had limits on the amount of current that can go out of the headphone jack. They also discovered that there is a delay between the app sending out the sound and it coming out of the headphone jack that was affecting using it for high speed photography (like lightning). I don't recall the details, but if you go back in their blog, it should give more details (or ask the developers).
Other possibilities are:
ADC to cover sound about right, so that combined with something that can talk as a host usb device for android would work.
Essentially I want to split the output from the audio jack to a hands free kit and back in through the usb to be collected by an app.
This seems to be a big problem for android as it looks like there is close to nothing out there with regards to collecting audio through the usb