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Old 27 April 2014, 13:09   #347
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Join Date: Aug 2013
Location: Croatia
Age: 35
Posts: 332
Dang, I had some buzzers I got with PC cases, who knows where they ended . Luckily I found some one ebay, 10 pcs for $2. At first I looked for "piezo speaker" and found only 5 pcs for $4-5.

My remote mod is finally finished, it took a long time for attiny's to arrive . Here's how it looks, Arduino is used only as 5V power supply

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And how it works inside A500, sensor is sensitive enough to work without "direct aim"

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Here's the schematic

And this is how it works:

Button push on gotek connects STM MCU pins PC7 (right button, counter up) or PC8 (left button, counter down) to GND. That's how it registers a click.

ATtiny receives signal from IR sensor on PB0 and depending on code received toggles it's PB1 (counter up) or PB2 (counter down) from high to low for short amount of time. This triggers STM pins PC7 and/or PC8 who and registers as a click.

LED that's connected to ATtiny's PB4 is used to signal when the remote is tuned. I'm using small universal remote that supports a lot of devices, it cycles through them when you press mute and when it gets to one that ATtiny recognizes it will use this LED to send signal so we know when to release the mute button. This only needs to be done once, when prepping new remote.

THere's a jumper connected to PB3, it's purpose is to separate two code sets at hardware level. ATtiny recognizes 4 code sets. If your TV turnes out to react to the same codes as ATtiny you can simply switch to next one and solve this issue. It wouldn't be nice if with ADF change you change TV channel . But it could be an issue the other way arround. ATtiny listens to all 4 code sets all the time. You could switch this mini remote to other set and solve interference with TV, but that wouldn't solve the other way around, ATtiny would react to TV remote. This jumper tries to solve that, it separates those 4 code sets to 2 and 2 on hardware level. If ATtiny reacts to TV remote simply put the jumper to those pins or remove it, what ever was at first, and it won't react to those codes anymore.

How it looks inside

Schematic is OK, but I have to rework PCB, this one works, but it could be better (read easier) to assemble. Mostly with capacitor that's under ATtiny. It's reeeeealy tight fit and that needs to be changed.
It works with either 5V or 3.3V power supply, STM MCU works at 3.3V but input pins are 5V tolerant so it shouldn't matter. At first I used 5V, then I tried 3.3V and it also worked fine. ATtiny runs at 8 MHz (interal oscillator) and that works with 3.3V, only case where 5V would be required is if it's run at 16 MHz (Internal PLL), that requires minimum of 4.3V. But it works fine at 8 MHz so that shouldn't be an issue. If anyone's interested I can upload eagle files and ATtiny hex and source.
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