0

Hack a MiniPOV3 for IR capture
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

Hack a MiniPOV3 for IR capture

by oPossum on Mon Jan 21, 2008 3:44 am

A MiniPOV3 can be modified for IR capture using ordinary banned 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:

Image


- 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

Image

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 :)
Last edited by oPossum on Mon Jan 21, 2008 7:25 pm, edited 1 time in total.
User avatar
oPossum
 
Posts: 636
Joined: Fri Oct 26, 2007 12:42 am
Location: Michigan, USA

by caitsith2 on Mon Jan 21, 2008 4:55 am

Is the minipov3 modded IR scope capture device, with an IR LED fast enough to capture the 455Khz B&O remote codes?
caitsith2
 
Posts: 217
Joined: Thu Jan 18, 2007 11:21 pm

by magician13134 on Mon Jan 21, 2008 11:40 am

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?
User avatar
magician13134
 
Posts: 1119
Joined: Wed Jun 13, 2007 9:17 am
Location: Ann Arbor

by adafruit on Mon Jan 21, 2008 1:34 pm

!!!!! this is AWESOME!

adafruit
 
Posts: 12149
Joined: Thu Apr 06, 2006 4:21 pm
Location: nyc

by Probedude on Mon Jan 21, 2008 2:07 pm

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
Probedude
 
Posts: 87
Joined: Sun Dec 23, 2007 3:16 am

by caitsith2 on Mon Jan 21, 2008 6:08 pm

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.))
caitsith2
 
Posts: 217
Joined: Thu Jan 18, 2007 11:21 pm

by oPossum on Mon Jan 21, 2008 7:18 pm

caitsith2 wrote: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.

Image
User avatar
oPossum
 
Posts: 636
Joined: Fri Oct 26, 2007 12:42 am
Location: Michigan, USA

by oPossum on Mon Jan 21, 2008 7:20 pm

magician13134 wrote: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.

Image
User avatar
oPossum
 
Posts: 636
Joined: Fri Oct 26, 2007 12:42 am
Location: Michigan, USA

by oPossum on Mon Jan 21, 2008 7:21 pm

ladyada wrote:!!!!! this is AWESOME!


!!!!! many THANKS!
User avatar
oPossum
 
Posts: 636
Joined: Fri Oct 26, 2007 12:42 am
Location: Michigan, USA

by adafruit on Mon Jan 21, 2008 7:23 pm

can you post what your firmware is doing? :)

adafruit
 
Posts: 12149
Joined: Thu Apr 06, 2006 4:21 pm
Location: nyc

by oPossum on Mon Jan 21, 2008 7:28 pm

Probedude wrote: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.
User avatar
oPossum
 
Posts: 636
Joined: Fri Oct 26, 2007 12:42 am
Location: Michigan, USA

by oPossum on Mon Jan 21, 2008 7:32 pm

ladyada wrote: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.
User avatar
oPossum
 
Posts: 636
Joined: Fri Oct 26, 2007 12:42 am
Location: Michigan, USA

by Probedude on Wed Jan 23, 2008 5:58 pm

caitsith2 wrote: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
Probedude
 
Posts: 87
Joined: Sun Dec 23, 2007 3:16 am

by oPossum on Wed Jan 23, 2008 6:22 pm

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.
User avatar
oPossum
 
Posts: 636
Joined: Fri Oct 26, 2007 12:42 am
Location: Michigan, USA

Like a remote, but diffrent...

by mightysinetheta on Fri Jan 25, 2008 11:58 pm

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?
--
m*lambda=d*sine(theta)
mightysinetheta
 
Posts: 1
Joined: Fri Jan 25, 2008 11:47 pm

Please be positive and constructive with your questions and comments.