Smartieparts Card With Voice Modification

Everything about the smartie programmer and backlight kit!
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Flaps 30
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Smartieparts Card With Voice Modification

Post by Flaps 30 » Sat Dec 29, 2012 5:43 pm

Having modified one of my transmitters for voice, it is now time to consider doing the same to my first one. I do see a problem, as the voice modification uses PB7 (pin 17 of the Atmega chip) as part of its system. Doing a quick check it looks like that pin is connected to the Pogo pin marked VDD on the Smartieparts card. My Smartieparts card is REV 2.1 which is the EL backlight version. So for that to work, it would need a the backlight feed from the voice card to go somewhere. The signal may have to be inverted (+V=On) from the voice card to make the backlight work. The logical thought would be that the VDD on the Smartieparts card would need to be isolated from PB7 (assuming that PB7 is only for the backlight) and the backlight from the voice card to go to the solder blob (VDD) instead.

So for the moment I am stuck as to what to do, or if I have it correct. Has anyone worked around this?


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Flaps 30
Posts: 1490
Joined: Tue Dec 27, 2011 6:04 pm
Country: -
Location: Wokingham Berkshire

Re: Smartieparts Card With Voice Modification

Post by Flaps 30 » Mon Dec 31, 2012 6:16 pm

Whilst doing another modification a quick check revealed that the VDD pin goes to just under five volts when the backlight is activated. Interfacing it with the voice modification seems pretty simple, all it needs as far as I can see is a direct feed to VDD (after isolating or removing the pogo pin) from pin 13 of the 74HC574. The only possible problem might be from the fact that the 74HC runs from 3.3 Volts, and that may not be enough for the smartiepart card.

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