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jonathanar1701

Built in Self Test - Basys3 Board

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Hi @jonathanar1701,

I have moved your question to the FPGA section of the forum where it is more likely to be seen by an engineer better suited to help you. That being said, I believe (as per this thread) that the Basys 3 uses the General IO demo, which is labeled as "GPIO" on our GitHub. From what I can tell, it only uses VHDL code (available on Github or in zipfile on our Wiki) and no IP cores.

Let us know if you have any more questions.

Thanks,
JColvin

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Hi @jonathanar1701,

@JColvin is correct. The general IO demo is the self  test the reference refers to. The demo is done in VHDL.  If you are looking into IP cores then I would suggest going through the getting started with miocroblase here. We have many Pmod  IP's here.

cheers,

Jon

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@jonathanar1701,

Yeah, that was my thought too when I first got my own Basys-3 board.  You know, ok, now I've got the seven segment display showing numbers, what about that colon between the numbers?  Looking over the instructions for the Basys-3 board, they only mention 8 and 4 wires: 8 cathodes, 4 anodes.  Given these 12 wires, there's no wires available to turn those colon LED's on.  This didn't make sense to me either, the reference manual must've been wrong, I thought, there should've been wires to connect to those colons.

So ... I went and checked the schematic.  You'll find the device on page 2 of the schematic, at the rough C2 position.  Looking there, I found no wires connected in the schematic that were not discussed in the documentation could then be wired up to light these.  Indeed, there's nothing in the schematic suggesting that it might even be possible.  So, the reference manual was right.

I then wondered, did Digilent cripple these light-points in their design of the board?  Looking at the schematic, I found the name of the part in question, the KW4-281ASB.  Googling this cryptic string led me to the specification sheet for the part Digilent used.  Looking over the specification, I could see that the device doesn't provide any wires for controlling that colon.

That just left me scratching my head.  Why would a manufacturer build something with a colon on it that looks like it would light up, but then never place an LED underneath it?  At this point, I came up empty, but at least I knew my answer: the part doesn't support it, therefore the board can't support it, therefore the reference manual doesn't mention them.

Bottom line: it can't be done.  Sorry,

Dan

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@jonathanar1701,

I should mention, my next thought was to see if I couldn't dim portions of the display.  My thought was that I should be able to PWM the individual LEDs on the display much like you can with the other LEDs on the board.  I couldn't understand why the manual limited the toggle rates of the individual LED's to only 1-16ms each.  I mean, why not toggle them at 10ns each, but in a PWM fashion that would turn some on for a less than 100% duty cycle?

Let's just say ... I was unsuccessful.

Perhaps I should try this again.  The problem I ran into was that, if you switch between the LED's any faster than about 1ms per LED, the LED's start to blur from one LED to the next.  What that means is that, while you might be turning on one LED and not another, the second one would dimly light because it was immediately following the first in the switching order.

I think with some more creativity I could solve this, but ... I've since moved on to other projects.  :D

Perhaps it is something you would like to try?

Dan

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