Hack a MiniPOV3 for IR capture

[oPossum]

A MiniPOV3 can be modified for IR capture using ordinary household items!

Here is a brief description of the mod...

- Connect pin 2 of the DE9 connector to pin 3 of the AVR. This will allow serial data to be sent to the PC

- Connect an 8 MHz resonator to pins 4, 10 and 5 of the AVR. The internal oscillator is not precise enough.

- Connect an ordinary IR LED to pins 7 (long lead) and 8 (short lead, flat side) of the AVR. An LED can emit *and* detect light.

Here is what it looks like:




- Enable external clock:
avrdude -p t2313 -c dasa -P COMx -U lfuse:w:0xCE:m

- Burn the firmware
avrdude -p t2313 -c dasa -P COMx -U flash:w:povcap.hex

- Run the software



Point the IR LED of the remote directly at the IR LED of the MiniPOV3 - they must be as close to each other as possible. Click the 'Capture' button and then press a key on the remote. The bottom red LED will flicker when IR is detected. If everything works right, a file named tvbg.c will be written with a C struct for use with the TV-B-Gone kit firmware.

No more begging for codes! Capture them yourself

[caitsith2]

Is the minipov3 modded IR scope capture device, with an IR LED fast enough to capture the 455Khz B&O remote codes?

[magician13134]

Absolutely fantastic work oPossum! Just when I needed this too!

I really like this! The only thing is, how did you connect the AVR to the serial port, I didn't see that in the picture... Just with a jumper wire?

[adafruit]

!!!!! this is AWESOME!

[Probedude]

Cool!
Can you share the C or assembly file? It would be great to modify the code to write the data to a serial eeprom to make it portable.

Dave

[caitsith2]

The eeprom only has 512 bytes, only enough to capture 51ms of data, not quite enough for every remote control protocol out there. For this application, you would have to add an external memory chip, ideally, at least 64KBs. (for 6550 ms of data capture. (10 bytes per ms.))

[oPossum]

Is the minipov3 modded IR scope capture device, with an IR LED fast enough to capture the 455Khz B&O remote codes?

Yes! It is on the edge, but it works great.

[oPossum]

The only thing is, how did you connect the AVR to the serial port, I didn't see that in the picture... Just with a jumper wire?

Here is a picture of the front side. A hole was drilled to pass the wire from one side to the other.

[oPossum]

!!!!! this is AWESOME!

!!!!! many THANKS!

[adafruit]

can you post what your firmware is doing?

[oPossum]

Cool!
Can you share the C or assembly file? It would be great to modify the code to write the data to a serial eeprom to make it portable.

Dave

The links in the first post have been updated to zip files with source.

I made a few improvements too, so discard anything downloaded prior to this post.

[oPossum]

can you post what your firmware is doing? :)

The theory is explained here. It is just an AVR port of the PIC based IR widget.

The primary design goal of the IR Widget was to make the circuit and firmware as simple as possible (PIC 10F series or 74HC series). There are better ways to do IR capture, but the circuit and firmware would be more complex.

[Probedude]

The eeprom only has 512 bytes, only enough to capture 51ms of data, not quite enough for every remote control protocol out there. For this application, you would have to add an external memory chip, ideally, at least 64KBs. (for 6550 ms of data capture. (10 bytes per ms.))

Thanks but I was intending on using an external serial EEprom. Even so since that takes milliseconds of time to write it isn't likely fast enough, internal or external, to keep up with the data stream.

[quote=oPossum]
The links in the first post have been updated to zip files with source.
[/quote]

Thanks!!
Dave

[oPossum]

FRAM is much faster than SEEPROM

The data rate could easily be reduced by using a 4 bit count rather than the full 8 bit count. Increasing the sample period to 150 uS would drop it even lower.

So 1 byte per 300 uS (each byte will have two 4 bit counts) = 3.333 KBps

A 300 mS sample would require 1K of storage. The maximum carrirer frequency would be 100 kHz ( = 15 / .000150 ).

I think this would be practical and simple to implement.

[mightysinetheta]

I'm working on extracting the IR signal from a system that I think (but have no way of verifying) is operating at a frequency of 11 MHz: thats what the clock is running at. Of course, it may be transmitting at a lower freq, but I cant tell. Would it even be feasible to try pulling the codes using the Minipov3 mod as it is, or should I up sampling frequency?