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# Confusing symbol on diagram

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#### kenny782

##### New Member
I'm trying to build this led "scanner" as part of a larger project.
On this diagram I see one symbol that I can't figure out.
I brought up several symbol lists I found on google and couldn't find it.

I circled the instances of the symbol in red.

Thanks,

Kenny

heeeeeeeeee, it's ground my dear boy!

That's what I was sure it was, I couldn't figure what else it could have been.
But I've never seen that symbol used for ground, and didn't want to blow anything up lol

Do you know anything about that ATtiny15L?
I have the code to program it with for 12 LED's.
But it's in hex, I'm just trying to figure out if I can expand it for a few more LED's

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Connect all that funny symbols together and you get common GND. Usually it goes to -Ve power supply terminal.

Do not forget to add my reputation....

my I assume you actually wanted to ask that terrible question..hm..and made this extremely simple quest. as a mask...what is that AT t in y 15L..dunno..at t in y 15Leds maximum..mightbe at t in z you get double - 30Leds..not sure..you know program those complicated thingies..but dunno GND..its commonsense..hm?

Thank you boy. now I have +1point and a promotion from bad to newbie. Thank you very much(tears..)

lol, anytime

my I assume you actually wanted to ask that terrible question..hm..and made this extremely simple quest. as a mask...what is that AT t in y 15L..dunno..at t in y 15Leds maximum..mightbe at t in z you get double - 30Leds..not sure..you know program those complicated thingies..but dunno GND..its commonsense..hm?
"AT t in y 15L" does NOT mean "15Leds maximum". "at t in z you get double" sorry again; there is no ATtinz. "AT" is Atmel; "Tiny" is a family of (small) microcontrollers; "15"is a member of the Tiny series, and "L" is low voltage (2.7V and up) version.

The circuit shown already uses 4 pins in the most efficient manner; called "charlieplexing". To drive more LEDs you need another pin.

I notice that they haven't used PB4 (yet). You could expand to 20 LEDs. You don't want to edit the hex code. Best try to find the author and see if you can get the source code. The development tools are free.

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Cool, nice catch
I'll try and get the source code.

Now wiring it, that's something else, I have a headache already. I think the breadboards gonna be busy LOL

Might take a while but I'm sure I can make enough sense of the code to add the extra led's

Kenny

Good luck finding an author. It seems to be presented as original work by several websites. I think ATTiny.com might be your best bet.

The photo shows a potentiometer, and the paragraph says speed control. It's probably (?) not implemented in the hex file that's posted since it's not on the schematic either.

There are examples of Charlieplexing on AVR Freaks and a recent article on a Cylon Eye without Charlieplexing on **broken link removed**, Smileys Workshop #2.

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