Author Topic: Idea for a Charlieplex Kit 2.0 (6 I/O, 30 LEDs)  (Read 5685 times)

chip273

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Idea for a Charlieplex Kit 2.0 (6 I/O, 30 LEDs)
« on: March 02, 2013, 06:48:05 am »
I did not really get why the charlieplex kit only uses 5 of the 6 I/O pins of the digispark. This gives us only 20 LEDs to write text, instead of the 30LEDs that would be possible with a 6 Pin Charlieplex shield.
So I have (quick and dirty) created a Eagle layout for a 6 pin Charlieplex Shield. I am not really into making/designing PCBs, so can anyone that knows about designing PCBs please look into it and tell me if I did any big mistakes ?


semicolo

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Re: Idea for a Charlieplex Kit 2.0 (6 I/O, 30 LEDs)
« Reply #1 on: March 03, 2013, 07:19:12 am »
Maybe because Voltage on PB5 is 3V instead of 5V, or because of PB3 1.5K onboard pullup?
Which pin isn't used on the official charlieplex shield?

chip273

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Re: Idea for a Charlieplex Kit 2.0 (6 I/O, 30 LEDs)
« Reply #2 on: March 04, 2013, 12:14:27 pm »
I did not know it has a 1,5k pullup. P5 labeled with P5 D/A is unused on the charlieplex board, as well as all the 3 pins on the supply side.

Bluebie

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Re: Idea for a Charlieplex Kit 2.0 (6 I/O, 30 LEDs)
« Reply #3 on: March 04, 2013, 03:36:08 pm »
If there's an unused pin, it might be cool to use it as IO to send strings in to the display! SoftwareSerial would do the job alright!

semicolo

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Re: Idea for a Charlieplex Kit 2.0 (6 I/O, 30 LEDs)
« Reply #4 on: March 05, 2013, 08:43:15 am »
Now that I read the datasheet a bit more to make the pinout diagram I know that P5 has a weak drive, it can only sink/source a few milli amps, so it's not a good candidate for charlieplexing.