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PModCLS backslash

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I have just recently purchased a PModCLS board.  After a bunch of hard (fun) work, I have it mostly up and running via the SPI port.  As a sample project, and at the kids' suggestion, I am using a mouse (connected to a Basys-3 board) to drive the display to create 'eyeballs' that follow the mouse around, or that change their mood as the mouse moves.  It's a fun project, and a fun demonstration of what the board can do.

My problem is that I'd like to use the backslash as one of the text-art characters in the eyebrows, and everytime I send the device a backslash a ... foreign character appears.  (It looks like a 'Y' with two horizontal bars through it.)  I know that the reference manual discusses being able to reprogram characters.  Can you tell me if all of the characters can be reprogrammed?  In particular, can I reprogram the backslash back into a backslash?  Or can I only create some special purpose characters using a limited part of the ASCII character set?



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Hi Dan,

I looked into this since I also recall having issues with the backslash character, and found that (bizzare as it seems) the backslash does not have a predefined character for it. The reason for this is because the PmodCLS uses the set of characters that is directly inside the memory of the KS0066 LCD controller that the host board (in your case a Basys 3) communicates with. The set of characters that it directly supports are here. (I'll update the PmodCLS reference manual to include this diagram as well) Why Samsung didn't include support in their LCD controller for a backslash is beyond me.

I am not aware of a way to directly reconfigure the pre-defined library, so what would be done in this case tell the controller to define a custom character within it's own memory. I can try to explain it if you want since the functionality is provided in the C++ library for MPIDE within the last three functions or so, but I'm not too familiar with FPGA's and their hardware language, so I won't be able to personally help as much there.

Let me know if you have any more questions.


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I finally got your example working.  May I highly recommend that you update your PmodCLS reference manual?  The example given in the PmodCLS manual doesn't work--or at least it didn't for me.  I needed to send an <ESC>[3p command after defining the character in order for it to show up on the screen.  Nothing in the reference manual suggested that would be necessary.  Indeed, if you could do a bit better of a job explaining the nature of that character table that is programmed into ROM from EPROM or RAM, I would appreciate it.  For example, is this just the 5 (or is it 6?) user definable characters that get programmed, or is an entirely new character set being programmed?  In other words, is there anyway to change the meaning of the backslash, or do I just need to suffer with using a user definable character of which (according to the MPIDE code you reference) it looks like there are only six of?

Thanks, though, for your help.  If the MPIDE code hadn't also done the <ESC>[3p command, I would've never gotten it!



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