AlexI did ordered a first batch of three prototype boards from OSH-Park. Compared to the last log there where not many changes, but I made some nice renders of this "rev0" board:
I did order stencils from OSH stencils and all missing parts as this tiny 2016 crystal. This crystal is also a optional part. The internal oscillator of the ATmega could be also used for first tests. But if using UART and high baud rates it was never reliable in earlier circuits.
I will soon publish at least the gerber files int the github repository.
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beautiful! Seems like a good practice to design a case and order it at shapeways... hmm.
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wait, how does this even work - are you charlieplexing?
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Thanks!
I am "just" using normal multiplexing. The display is divided into 16 rows and 3*4=12 columns. I think it's a bit to early to think about a case. First it should run.
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This multiplexing will be also visible in the schematic. I will upload it soon, but first I should clean it up a little bit.
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kk, now that I see it, it makes more sense, also know that I notice the change of brains. I assumed you were using an atmega328 for that. 28 IOs - nothing for an arduino pro mini clone :D I don't see any current limiting, not necessary or no room for it?
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there is no current limiting. Mostly because of space reasons. All current limiting will be because of the time and the limited drive strength of the ATmega. This is not the best solution, but it should work.
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I'm looking into multi channel LED drivers right now, but you'd still have to have place for that and 8 or 4 mosfets, but they might be chainable. And also probably won't fit on your small boards :D still good to for me to read up on those things :)
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I used LED sink drivers and p-fets in #384:LED. For the LEDs and maybe the the total brightness this is the better solution I think. I will be able to compare it soon. The LEDs drivers are available in smaller packages, but there is nearly no space left for components on the back.
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I'm looking forward to see all of them! Again - great work!
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