digitalForest
Posts: 7
Joined: Sat Jun 01, 2013 10:19 am

Controlling a TV B-Gone with a Raspberry Pi

Tue Feb 25, 2014 8:31 pm

Adafruit's TV B-Gone kit (http://www.adafruit.com/products/73) is such a simple device, yet so effective and provides plenty of silly joy.

Here is what I would like to achieve: Connect a Pi to the network and run webiopi on it. One button let's you take a picture to see if the TV is on, the other button then let's you turn off the TV.

I am struggling with the way I can activate the kit. From the description (http://learn.adafruit.com/tv-b-gone-kit/design-notes), it says, that
"There is one button. Pressing & releasing will start the kit to emit IR codes. The button is actually hooked up to the microcontroller's reset pin and tells the chip to reset. When the chip resets it automatically emits all the codes in its library. When it's done it goes into a very-low-power sleep mode and awaits another button press. "

The schematic further below on the same page shows how the button S1 connects RST to GND in order to activate the TV B-Gone. I might have missed something, but it seems, that the Pi can only send 3.3V or nothing under webiopi (or in general) and not connect something to GND. So I am thinking of putting in a 3V relay to connect RST to GND.

Is my thinking correct or did I miss something obvious?

Thanks for your help

dF

dan3008
Posts: 1172
Joined: Wed Aug 15, 2012 1:05 pm

Re: Controlling a TV B-Gone with a Raspberry Pi

Wed Feb 26, 2014 7:52 am

Not made a TV-B-Gone myself, so I cant be certain (on my todo list when my order of attiny85's arrives) but sounds like it should work. The other option would be to replace the battery itself with the pi. simply connecting positive to an addressable gpio pin, and negative to ground, you should be able to turn it on and off by sending the positive pin high and low. (hope that makes sence)

Of course, if you've not already got a TV-B-Gone, then you might want to look into just attaching the infared led's to the pi, and controlling them from that
dan3008 wrote:Pays your money, takes your choice

digitalForest
Posts: 7
Joined: Sat Jun 01, 2013 10:19 am

Re: Controlling a TV B-Gone with a Raspberry Pi

Wed Feb 26, 2014 8:28 am

Thanks for the reply Dan,
dan3008 wrote:The other option would be to replace the battery itself with the pi. simply connecting positive to an addressable gpio pin, and negative to ground, you should be able to turn it on and off by sending the positive pin high and low. (hope that makes sence)
I thought about that as well, but the power draw from the LEDs can reach 400-1000mA easily. I think the GPIO pins are rated for max 50mA in total or even less. The TV B-Gone works with a supply voltage of 2.5 - 5.5V with higher voltage giving longer range.

Seems to me, that unless there is a way of connecting RST to GND via the Pi, I will have to use a relay. With a relay, it wouldn't make much of a difference to either short circuit the reset pin or supply power to the kit for about 2.5 mins (duration of a cycle).

dF

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