I'd like to know if it is theoretically and/or practically possible to enable a smartphone (iOS or Android) to communicate with another device via IrDA (IrCOMM) using a simple infrared transceiver that's plugged into the 1/8" audio jack.
The IR transceiver would be as minimal as possible: just an IR LED and IR receiver soldered to a typical 4-conductor 1/8" audio plug.
The basic idea is that the app would read/write to the audio port to control the IR transceiver to talk to another IrDA device. We're assuming the IrDA protocol stack is implemented in the app.
Are there any physical limitations of an audio port, such as the frequency range, timing precision, power output, mic sensitivity, etc., that would prohibit controlling an IR transceiver to the extent necessary to communicate via the IrDA protocol?
We've seen the simple DIY television remote controls for iPhones, but they are only transmitters at specific frequencies (and even in those simple cases there were complexities involved in producing the 38kHz carrier frequency). In our case we're interested in two-way complete support for IrDA.
Any insight would be most appreciated!
Just to clarify, in my understanding there are two ways to approach this: (1) IrDA stack in hardware, or (2) IrDA stack in software.
In case (1) you would use an IrDA transceiver (e.g. IRMS6118) with an IrDA encoder/decoder (e.g. MCP2150) connected to a microcontroller with a modem plugged into the audio port and the smartphone app would use FSK modulation via the audio API's to talk to the modem. So:
App > FSK > Audio Port > Modem > Controller > IrDA Coder > IrDA Transceiver
In case (2) you would skip the digital conversion altogether and the app would use the audio API's to directly control an LED and IR receiver (in which case the app would be responsible for implementing the lower levels of the IrDA stack for handshaking, etc.). In this case the IR LED and receiver would simply be soldered directly onto a 4-connector 1/8" audio plug (no circuit boards or IC's or power source or anything).
App > Audio Port > IR LED/Receiver
I've done quite a bit of searching online but haven't found any mention of either of these as working prototypes.
For case 1, some folks have the audio-to-modem part working (e.g. softmodem) and others have the IrDA-to-controller working (e.g. sor) so putting them together seems reasonable.
But I have not found any mention of case 2, and I'm wondering if it is because (a) it's just not possible for the audio API's of a smartphone to control an IR LED/receiver via an audio port well enough to implement the IrDA protocol, or (b) there are no software implementations of the IrDA stack available, or (c) it would be too much work to port the software stack over to the mobile platforms, or (d) some other reason.