Wednesday, March 3, 2010

RedEye mini coming to iPhone; DIY coming soon

UPDATE 11 Nov 2010: it turns out I was wrong about it being the simple option, and right about the "at most" part. Thinkflood mentions the simple option themselves in a semi-technical writeup of the technology, but goes on to mention the shortcomings of this approach. Instead, they use a microcontroller to blink the LED, and the audio frequency signals are only for communicating with and powering up the microcontroller. This of course means that while the communication protocol between the software/phone and the Mini hardware can be reverse engineered, the microcontroller will still have propriatary code to drive the LEDs; it looks like reverse engineering this isn't going to be fun, easy, or cheap any more, so I guess this project is out. Old post follows.

Old Post

I'm excited about this product that claims to turn your iPhone/iPod Touch into a universal remote control.

This takes me back to the old days of my Palm m505 that had built-in IR, and plenty of programs that did the universal remote functionality. Since the iPhone doesn't have built-in IR functionality, ThinkFlood decided to make a "hardware" component that costs $50 and plugs into your headphone jack. There is some free-of-cost software to drive it that has the universal remote functionality. I use quotes around hardware because my sense is that this is probably nothing more than an IR LED or two connected to a 3.5mm connector. All the smart stuff is clearly done in the software, which generates audio signals to drive the LED.

At MOST, the device has a watch battery, a few transistors, a microcontroller and an LED. Lets hope not.

I'm going to try and reverse engineer this thing and make a cheap device that works with the official RedEye app. The audio output should be able to be recorded and analyzed as a starter. Gutting a RedEye mini would be the other part. Stay tuned.

PS: Here are some relevent links that will help in the hacking.


1Kid said...

Any news on the reverse engineering?
when i discovered that thing i was thinking the exact same
i just don't have access to a oscilloscope in the moment.

although i doubt that the headphone plug will output the carrier frequency
(or maybe the left and right audio channel are phase shifted to double the frequency, or there are diodes to rectify a sine to a half-sine pulse ??)

keep me informed pls! thanks

Raj said...

1kid: I don't think that it's out yet. As soon as it is I am going to buy one and try it out.

Vitim said...

Im downloading the app on the appstore, and i will try analize the audio in my sound card input. if i can see a 38khz square wave is sure it isonly a led, but i cant know if the iphone can operate in this frequency.

Probably the software export pulses in some audible frequence, and the hardware only modulate pulses in 38khz.

some news please email me.

Raj said...

Vitim: i don't imagine the iPhone A/D converter works up to this frequency; audio hardware rarely goes above 20kHz.

That said, a 19kHz signal driving TWO LEDs in parallel, facing opposite directions would effectively pulse at 38kHz (one would be on during the positive half cycle, the other during the negative). This frequency is surely achievable with any audio hardware, so here is hoping that this is what they do since it requires next to no hardware in the transmitter.

Vitim said...

really the half-sine is posible to generate a 38khz infrared signal, is totally hardware free, but the output power have the suficient voltage to light up the infrared led? i donwloaded the redeye in appstore, but i cant do anything, the redeye mini need other app? is already avaliable on appstore?

i will try make a test with an generated audio signal in pc, and try on the ipod aplication. i need buy IR LEDs.

thanks for the feedback

1Kid said...

Raj said...

1Kid, thanks for the update. I had not seen this update from RedEye yet. As soon as they release this though, I'm going to take a look at figuring out how it works.

Raj said...

I take that back, new updated software is out! Let the reverse engineering begin.

1Kid said...

it seems to have a serial number validation, which is not half stupid seen from their point

Raj said...

Ah yes, pretty clever. Well, someone will probably come up with a serial number generator :-)

Hell, I was probably already going to buy this thing anyway.

Mike said...

Any update? Cracked one open yet?

Raj said...


No, not yet. It turns out that the option they chose is close to the most complicated option I outlined. Its almost as if they read the blogs, and did a short semi-technical write up of the technology, as I've put in the updated link above.

That said I'm still getting one of these soon.

Victor B. said...

let me understand, that thing is microprocessed? that is not possible..

Raj said...

Yeah victor, read the page I linked. Microprocessors can power up and work on tens of milliwatts, and the output of an audio chipset can easliy deliver a few hundred milliwatts. This research group has sensor nodes that can power up from incoming RF power and perform real data communications. Full disclosure, I'm affiliated with this lab.

bazazz said...


Did anyone manage to get anywhere with this?

I have one and their software is pretty bad...

Raj said...

I gave up on this when I realized that they were using the audio link for communication to the dongle, and the dongle was doing lots of other smart things.

Anyone else play around with this? I'd be glad to post / host information about reversing the protocol.