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Loredana

PmodOLEDrgb doesn't work on Zedboard

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Hi,
I tried to make the tutorial "Getting the PmodOLEDrgb to work on Zybo" available on the instructables.com website to work for Zedboard. 
When I program the FPGA and run the application nothing gets displayed on the OLEDrgb Pmod.
Are there any setup steps that need to be done?
I have no error messages and no warnings.
Best regards,
Cris

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@Loredana,

I just went through a similar pain, but rather to get the OLEDrgb up and running on the Arty without using MicroBlaze.  To answer your question, are there setup steps?  Yes.  There are many.  I would assume the project you have is using them, but I refuse to register with the instructable's site in order to find out what's in their package.  (Sorry ...)  The worst part about all the steps involved is that they are not discussed in the reference manual.

Your description, though, of the test failing with neither error messages nor warnings is ... well, it doesn't tell you much, now, does it?  ;)  One problem with creating errors or warnings when using the OLEDrgb is that, as it has been designed, there are no feedback wires from the OLEDrgb back to the controller.  The pseudo-SPI port works in one direction only, writing to the board.  Reads don't do anything.  Indeed, there are no data pins returning from the board at all.  Ouch!  That doesn't tell you much, now, does it?  In other words, you might be struggling with anything from plugging into the wrong PMod port, to not powering the OLEDrgb on correctly, to sending messages across the wrong port (data vs control), to sending misformed messages across their pseudo-SPI controller.  A lack of feedback from the device when the display isn't working just doesn't help much.

For this reason, I built my own test-bench for the device using gtkmm-3.0.  It creates, from Verilator, a window that will display (roughly) what the device screen should see.  However, since Verilator is at best a simulator, and since it isn't really designed to work with the X-windows server on my Linux workstation, the display seems to take forever to update.  Indeed, it is *so* slow that I'm likely to remove it from my Arty test bench entirely--just 'cause it slows everything down so much.

In the end, I found the Digilent MPIDE example the most useful for getting started.  Their example goes through the essential steps of setting up the OLEDrgb, although it only does so for the ChipKit boards so ... I'm not sure what that means for getting it running on a Zybo.

If you are interested in my own approach, you can find my software posted on GitHub.  This includes both a Verilog controller (controlled via a Wishbone Bus, rather than AXI), a lower-level Verilog controller, as well as an example program for the ZipCPU that communicates with the PMod.

Dan

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