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Making Open-Source TV-B-Gone?
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Making Open-Source TV-B-Gone?

by magician13134 on Sun Dec 23, 2007 10:03 am

Hi, I recently started working on making a TV-B-Gone from scratch, starting very simple with the Open Source firmware from CornfieldElectronics.com, but I'm not using an external oscillator or a transistor at this point. Are either of those absolutely necessary? I'm just holding it a couple inches from the TV, so the LED shouldn't need a transistor, right? And I didn't think an external clock was necessary either. I simply have the code programmed onto an attiny2313, no modification with +3V to pin 20, ground to pin 10 and an IR LED from pin 14 to ground. A camera verifies that the IR LED is indeed blinking brightly. One thing I noticed is that there are pauses in the script (say 250ms) that are MUCH more than 250ms from the LED. Is that something to do with the internal oscillator? Thanks for the help

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EDIT: I had forgotten to do "make burn-fuse" which I did, and it worked, so I reburned the firmware, the timing now looks right, but it still won't turn on/off TVs. Any ideas?
Last edited by magician13134 on Tue Jan 08, 2008 5:33 pm, edited 1 time in total.
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by adafruit on Sun Dec 23, 2007 3:13 pm

you really need the oscillator. its only 50 cents or so.

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by magician13134 on Sun Dec 23, 2007 3:27 pm

I know, but I can't get it for a week or more due to the Holiday season, no where will ship, and the only electronic store I know of around here (Radioshack) doesn't sell them, so until then I'm stuck without one.
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by caladan on Sun Dec 23, 2007 3:45 pm

Internal RC oscillator is not stable. Well, in fact it is very unstable :> I tried running UART on internal one and there are many problems. So i guess you can set now for internal but make place for XTAL and solder it when you have one - and burn right fuse bits..
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by magician13134 on Sun Dec 23, 2007 4:40 pm

I'm using a solderless breadboard for now. I'm confused about how to put it though, it has three pins, two attach to the microcontroller, and one to ground? But won't the one that's attaching to ground get in the way? Did that make any sense?
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by Probedude on Sun Dec 23, 2007 5:25 pm

magician13134 wrote:I'm using a solderless breadboard for now. I'm confused about how to put it though, it has three pins, two attach to the microcontroller, and one to ground? But won't the one that's attaching to ground get in the way? Did that make any sense?


Then you need to put it somewhere else on your breadboard and wire over the 2 legs to the microcontroller. Put it nearby so the wires are short.
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by oPossum on Sun Dec 23, 2007 5:26 pm

Place the resonator in the breadboard so that the left most pin conects to pin 3 of the AVR and the center pin to pin 4 of the AVR (ground). Install a short jumper wire from the right most pin of the resonator to pin 2 of the AVR.
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by adafruit on Sun Dec 23, 2007 5:30 pm

magician13134 wrote:I know, but I can't get it for a week or more due to the Holiday season, no where will ship, and the only electronic store I know of around here (Radioshack) doesn't sell them, so until then I'm stuck without one.


sadly, not having the part doesn't make it unnecessary! :)

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by maltman23 on Sun Dec 23, 2007 6:07 pm

I've had some success using the AVR chip's internal oscillator to turn off TVs. The beginnings of this TV-B-Gone Kit came from a hack I did from the MiniPOV3 kit (I've hacked that kit into a bunch of cool things -- it's a really nice, minimal AVR development board!). At workshops that I give (using the MiniPOV3 as a starting point to teach how to build cool things out of microcontrollers), about 50 people built TV-B-Gones, hacked from the MinPOV kit, all without ceramic resonators, and all but one would turn off a Sony TV that I have for just testing TV-B-Gones (Sony TVs are the best -- they turn off so easily!). But, the internal oscillator is not so stable (it varies with temperature and voltage, and who knows what else, sunspots?), so you can't really rely on it for precision timing (and even though 49 out of 50 turned off my Sony test TV, they may not turn off the other makes and models that are less forgiving with their timing).

Mitch.

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by magician13134 on Sun Dec 23, 2007 6:54 pm

ladyada wrote:
magician13134 wrote:I know, but I can't get it for a week or more due to the Holiday season, no where will ship, and the only electronic store I know of around here (Radioshack) doesn't sell them, so until then I'm stuck without one.


sadly, not having the part doesn't make it unnecessary! :)


I know... isn't that a shame? It'd make this all so much easier...

maltman23 wrote:I've had some success using the AVR chip's internal oscillator to turn off TVs. The beginnings of this TV-B-Gone Kit came from a hack I did from the MiniPOV3 kit (I've hacked that kit into a bunch of cool things -- it's a really nice, minimal AVR development board!). At workshops that I give (using the MiniPOV3 as a starting point to teach how to build cool things out of microcontrollers), about 50 people built TV-B-Gones, hacked from the MinPOV kit, all without ceramic resonators, and all but one would turn off a Sony TV that I have for just testing TV-B-Gones (Sony TVs are the best -- they turn off so easily!). But, the internal oscillator is not so stable (it varies with temperature and voltage, and who knows what else, sunspots?), so you can't really rely on it for precision timing (and even though 49 out of 50 turned off my Sony test TV, they may not turn off the other makes and models that are less forgiving with their timing).

Mitch.


So would you recommend trrying another microcontroller? I have a dozen or so...
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by adafruit on Sun Dec 23, 2007 10:22 pm

magician13134 wrote:So would you recommend trrying another microcontroller? I have a dozen or so...


the microcontroller is irrelevant, ANY microcontroller will not have a good enough internal oscillator, they're just not stable enough!
there's 10 posts in this thread, and the answer to your question is still "NO"! so its kind of silly to keep asking :)
Last edited by adafruit2 on Sun Dec 23, 2007 10:26 pm, edited 3 times in total.

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by maltman23 on Sun Dec 23, 2007 10:23 pm

magician13134 wrote:So would you recommend trrying another microcontroller? I have a dozen or so...


Sure, while you're waiting for the ceramic resonator to ship to you, why not try a few micros and see if any work?

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by maltman23 on Sun Dec 23, 2007 10:25 pm

ladyada wrote:
magician13134 wrote:So would you recommend trrying another microcontroller? I have a dozen or so...


the microcontroller is irrelevant, ANY microcontroller will not have a good enough internal oscillator. there's 10 posts in this thread, and the answer to your question is still "NO"! so its kind of silly to keep asking :P


My post hit as Ladyada was writing this. :oops:

Just keep in mind that if you try a micro and it works with the internal oscillator, it doesn't mean that it will work the next day (at a different temperature, or a weaker battery, or a stronger battery, or a different TV, etc.)

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by adafruit on Sun Dec 23, 2007 10:53 pm

mitch is an optimist, and im a pessimist :)

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by magician13134 on Sun Dec 23, 2007 11:15 pm

Yeah, I was just going with Micth's 98% statistic, I like optimism!
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