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Help with Electrical Schematic

Posted: Thu Jan 17, 2008 3:06 am
by Alathald
Wasn't sure where to put this but modding seemed appropriate...I've just got a couple questions on a schematic I found online and was hoping you guys could help out.
I'm fairly confidant of the variable resistor and the GND (oddly draw GND tho) but just wanted some help on the other two components. I think the one piece is a oscillator but I can't for the life of me figure out where the PC6 wire goes. The other PC wires go to the variable resistors but not PC6 and I can't find it anywhere else.
schematic.png
schematic.png (64.45 KiB) Viewed 2310 times
Thanks for the help! and in case you're wondering, I'm researching how to build a gamepad and these schematics look quite promising. I found them here: http://www.flightsim.com/cgi/kds?$=main/howto/mind.htm

Re: Help with Electrical Schematic

Posted: Thu Jan 17, 2008 7:00 am
by bubba
hit up some reference guides I had saved. It looks like what your calling the oscillator is a Piezoelectric Crystal (don't ask me, I'm going by the symbol), and what you are seeing as a ground could be, its missing some lines but the guy/gal who drew could have left them off (slacker). I can't find in any of my reference stuff a symbol that looks like it other than the ground. Looking at the schematic again port 8 is marked as ground and he is using the single line to represent it. The ground symbol should look like an upside down triangle made of 3 horizontal lines...

Links

http://www.symbols.net/electrical/
http://library.thinkquest.org/10784/cir ... mbols.html

Looked at the link you posted. In the paragraph above the schematic..
The main brain is ATMega8 microcontroller in DIP package with 12 MHz quartz resonator

Thats most likely the crystal for symbol you are calling the oscillator.

Re: Help with Electrical Schematic

Posted: Thu Jan 17, 2008 7:17 am
by Zertz
Yes it's a crystal

Whatever software was used to draw this, it kind of blows :|

Re: Help with Electrical Schematic

Posted: Thu Jan 17, 2008 11:07 am
by Alathald
bubba wrote:Looked at the link you posted. In the paragraph above the schematic..
The main brain is ATMega8 microcontroller in DIP package with 12 MHz quartz resonator
Thats most likely the crystal for symbol you are calling the oscillator.
>_< D'OH! That's what I get for researching this stuff with no sleep :oops:
But, yeah, that's what I was thinking of, a crystal oscillator, a quartz resonator, a piezoelectric crystal...all the same. I couldn't find anything about what it was last night and I've always drawn them as a circle enclosed in brackets (don't know why but I have a feeling I've been drawn the wrong component, ah it's just a hobby). Thanks for solving that one for me!

Any clue where the PC6 pin goes? Is it used for programing the chip? I've never done this before so I'm trying to figure this stuff out. I basically know nothing about programming a chip or USB protocols and figured this would be a good learning experience...Plus I'll (hopefully) have a nice, custom, (and hopefully well documented) gamepad.

As for the quality of the schematic, I think the guy used MSPaint so, yeah...that would explain the poor quality.

EDIT: I found what appears to be a decent data sheet on the ATMega8 chip at http://www.futurlec.com/Atmel/ATMEGA8.shtml time to bust out my computer architecture and design book and give this chip a good once over (probably more like 10-20 times over...) I might have some more questions for you guys later but I've got a decent resource for now, thanks again for the help! Hopefully I can still find this chip for sale...haven't looked yet >_<