JP1 Remotes

[irhacker]

Hi,

I want to design and build a very, very simple remote control for my camera.

* 3 codes
* Low cost
* Compact design

I know I can use my universal remote for this, and the codes are available, but I'd like to make something more compact and convenient. I also want to add a shutter release cable etc, so these are all improvements I can make after I have a prototype.

I've built various electronics projects before, have experience of soldering, pcb work, programming etc, so I'm not afraid to try this out. I don't however have a great understanding of the operation of remote controls, in terms of protocols etc.

I was thinking that this would probably be a 'parrot' device, i.e. no great understanding of remote protocols, not highly configurable - more something that can just send the appropriate pulses.

My main questions are:

1. Are there any highly integrated packages that could make the schematics for a project like this as simple as possible?

2. Any hints for taking the protocol, codes etc and actually programming this thing? I suppose this will be highly dependant upon the design - e.g. carrier fequency, but I don't have a great understanding of how remotes work - any links that would help?

3. I have access to PIC programming equipment etc. at work. Is this route worth investigating, or are there specialised packages that would be simpler to use as a basis.

4. It's almost guaranteed that someone has done this before. Has anybody got links to a similar project?

I'd really appreciate if someone could tell me if this project is worth pursuing, or whether it will probably be more hassle than it's worth. I like a challenge though!

Many thanks!

[Herbie]

Microchip makes a line of 8-pin self-contained processors. They include an internal RC oscillator, so all you need is to connect them to power and ground, and you have 6 I/O pins.

I think a "parrot" device would actually be more complicated than just figuring out the protocol timing, because once you know the protocol you can just write simple routines in the PIC to bit-bang out the codes via one of the GPIO lines. That pin would drive a transistor that drives an IR LED, and you're there.

I suppose you could try to come up with a scheme to "learn" signals into a format where you just get a big collection of on/off pulses (or hex values in series) and then you can copy those into an array in the software and just step through it, but the code will be more compact if you can just figure out how to GENERATE the protocol.

The hard part of making any device "compact" is usually the power supply. In this case, you'd need at least 3 volts (2 AAA), just to have enough voltage to forward bias the IR LED. I don't remember the minimum operating voltage of the smaller PICs, you might need to add one more battery (4.5v) unless you can get a low-voltage part.

As for "worth it"? Only you can answer that. I like to take on projects and create solutions, but OTOH my idea of a good time is usually not to reinvent the wheel.

For any IR project, I suggest you look at this thread from Tommy Tyler, its a trick little IR detecting scheme.
_________________
TiVo FREAK!
Brutalizing my 15-1994 since 2000, thanks to JP1
Now abusing a 6131m, 2116, and 2104 too!

[The Robman]

I don't know just how much re-inventing you really want to do here, so this idea may not appeal to you as it's a shortcut to the whole process, but you could take one of the UEI remotes that has a DIP style processor onboard (along with an EEPROM chip) then you could transfer these 2 items over to your homemade remote. That way, if you take care of the actual construction, you can use JP1 to program the remote to send the right signals to your camera.
_________________
Rob
www.hifi-remote.com
Please don't PM me with remote questions, post them in the forums so all the experts can help!

[irhacker]

I think avoiding reinventing the wheel, as you point out, is the way to go. No point in spending the time coding, when I could be working on the usability of the overall device.

I think I'll try and pick up a low cost UEI, and look into reclaiming the bits I need. This along with JP1 to get the proven codes programmed will almost guarantee I'll end up with something that works, and with a lot less bugfixing.

I'll let you know how I get on.

Thanks again folks.

[The Robman]

It's not so important that you find a low cost UEI remote as it is that you find one with a DIP style MCU chip and an EEPROM.

Most modern UEI remotes have surface mount MCU chips that are hidden under a glob of epoxy, which makes them virtually impossible to transfer from the remote to your PCB.

While there are some modern remotes that have DIP style chips on board, you're much more likely to find these in the older 6805 remotes. Also, it's not important that the remote have a 6-pin connector, but it is important that it have an EEPROM onboard (or at least provision for one). Without an EEPROM you will have no way of re-programming it.

Ideal candidates for this include:

Radio Shack 15-1918
Radio Shack 15-1919
Radio Shack 15-1925
One For All URC-7070

There are many other UEI remotes with DIP style chips but I don't remember them all as it's not usually a criteria that we care about. Hopefully others will add model numbers to the list.
_________________
Rob
www.hifi-remote.com
Please don't PM me with remote questions, post them in the forums so all the experts can help!

[irhacker]

> Hopefully others will add model numbers to the list.

That would be handy. Also, I'm in the UK and the model numbers seem to be different over here, so UK numbers would be a bonus. I can probably search about and find info on the difference in naming myself though.

Cheers!

[The Robman]

The Sky+ remote would work.
_________________
Rob
www.hifi-remote.com
Please don't PM me with remote questions, post them in the forums so all the experts can help!

[classicsat]

What I would do is hit the surplus stores looking for any old small remote, and code a receiver decoder to respond to the codes it emits.

Failing that, I'd salvage the chip from an OEM remote, and write receiver code for it. The last thing I'd do is to use a universal.