CODEWITHSUNDEEP
android-things
Paweł Byszewski
Paweł Byszewski

Reputation: 420

IR receiver powered by AndroidThings

Is it possible to implement IR receiver on android-things?

1st idea:
Use GPIO as input and try to buffer changes and then parse the buffer to decode a message.
findings:
GPIO listener mechanism is too slow to observe IR signal.
Another way is to read GPIO infinite loop. But all IR protocols strongly depend on time and java(dalvik) in this case is to less accurate.

2nd idea
Use UART findings:
It seems to be possible to adjust baud rate to observe all bits of a message but UART API require to setup quantity of start bits etc. and this is a problem because IR protocols do not fit that schema.

IMHO at the moment, UART is the only path but it would be a huge workaround.

Upvotes: 1

Views: 1338

Answers (2)

Fabio
Fabio

Reputation: 2824

I believe you can't process the IR signal in Java because the reading pulses would be quicker than the reading resolution-at least in a raspberry pi. To get faster gpio readings I'm confident you can do in c++ with ndk with the raspberry. Though it's not officially supported there's some tricks to enable it. See How to do GPIO on Android Things bypassing Java on how to write to gpio in c. From there it should be trivial to read in a tight loop. Though I would still try to hook the trigger from Java since so far I have no clear easy idea on how to write/install interrupts in c.

Upvotes: 0

devunwired
devunwired

Reputation: 63293

The overarching problem (as you've discovered) is that any non-realtime system will have difficulty parsing this input directly because of the timing constraints. This is a job best suited to a microcontroller where you can access a timer interrupt. Grab an inexpensive tinyAVR or PIC to manage the sensor for you.

You will also want to use a dedicated receiver sensor (you might already be doing this) to simplify parsing the signal. These sensors include a demodulator, which means you don't have to deal with 38kHz pulse signal and the input is converted into a more standard PWM wave.

Upvotes: 3

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