LCD Panels and Hybrid Guzunty

[paulhamsh]

LCD Panels and Hybrid Guzunty

[campbellsan]

Hi Paul,

• When will your daughterboard be available again (your wiki has said a few weeks for quite a few weeks now)

Real soon now, probably this week. The PCB fab took an unusually long time to process the re-order. I'll update the wiki to reflect the new expectation.

Because it is of general interest, I have answered your other question here:

http://www.raspberrypi.org/forum/viewtopic.php?f=41&t=49352&p=482400#p482400

[paulhamsh]

Hi
Thanks for the quick response!
I am confused now, though.
I have studied the lcd schematic and I can't see how it makes any difference to the Pi whether the connection is direct to the lcd or via the Guzunty CPLD. Do you mean the Guzunty runs out of io pins, or just runs out in standard configuration?
Paul

On 7 Jan 2014, at 14:01, campbellsan [email protected] wrote:

Hi Paul,

When will your daughterboard be available again (your wiki has said a few weeks for quite a few weeks now)
Real soon now, probably this week. The PCB fab took an unusually long time to process the re-order. I'll update the wiki to reflect the new expectation.

Because it is of general interest, I have answered your other question here:

http://www.raspberrypi.org/forum/viewtopic.php?f=41&t=49352&p=482400#p482400

—
Reply to this email directly or view it on GitHub.

[campbellsan]

I have studied the lcd schematic and I can't see how it makes any difference to the Pi whether the connection is direct to the lcd or via the Guzunty CPLD

I started to write a long explanation and realized that I'd probably end up confusing you more. Instead, let me make the following observations about the core design as it currently is:

• It supports the daughter card very well.
• While it adequately supports wiring an LCD module directly to the Guzunty header pins, the design could probably support this use case better with a bit of work.
• Some of the reasoning behind the pin assignments was to avoid having to make too many physical cuts or links to the standard Guzunty board. Now that I return to this after some months, I think the pin assignments could have been done better.
• Again, with a bit of work, touch might be possible to support with a daughterless configuration, but JP15 would definitely have to be linked underneath at a minimum, since it must carry the SPI second channel selector signal (and that would have to be routed through the CPLD).

I hope these additional comments help and don't confuse matters further. Basically, the LCD core design isn't perfect, so there isn't necessarily a good answer to every 'why'. The design of the physical routing of the Guzunty board does not have such problems, which is fortunate since they would be much more difficult to fix.

Finally, you were asking about running out of I/O. I think the answer is your latter suggestion; we don't have a shortage of CPLD I/O, but we do start to run into the need to permanently reconfigure the Guzunty PCB. Such reconfiguration begins to compromize the Guzuntys general purpose capability, another reason to just build a daughter card if you want to play with LCD modules.

Do feel free to ask further questions if this didn't help.

[paulhamsh]

Hi
Thanks for the response. I get it now. I've checked the schematics and I can see that you can only get it to pass signals through with some soldered jumpers!
I have put some tables together to help me understand it all in a Word document - it might help others, should I send it to you? If so, is this the best email address?
Thanks
Paul

On 8 Jan 2014, at 23:29, campbellsan [email protected] wrote:

I have studied the lcd schematic and I can't see how it makes any difference to the Pi whether the connection is direct to the lcd or via the Guzunty CPLD

I started to write a long explanation and realized that I'd probably end up confusing you more. Instead, let me make the following observations about the core design as it currently is:

It supports the daughter card very well.
While it adequately supports wiring an LCD module directly to the Guzunty header pins, the design could probably support this use case better with a bit of work.
Some of the reasoning behind the pin assignments was to avoid having to make too many physical cuts or links to the standard Guzunty board. Now that I return to this after some months, I think the pin assignments could have been done better.
Again, with a bit of work, touch might be possible to support with a daughterless configuration, but JP15 would definitely have to be linked underneath at a minimum, since it must carry the SPI second channel selector signal (and that would have to be routed through the CPLD).
I hope these additional comments help and don't confuse matters further. Basically, the LCD core design isn't perfect, so there isn't necessarily a good answer to every 'why'. The design of the physical routing of the Guzunty board does not have such problems, which is fortunate since they would be much more difficult to fix.

Finally, you were asking about running out of I/O. I think the answer is your latter suggestion; we don't have a shortage of CPLD I/O, but we do start to run into the need to permanently reconfigure the Guzunty PCB. Such reconfiguration begins to compromize the Guzuntys general purpose capability, another reason to just build a daughter card if you want to play with LCD modules.

Do feel free to ask further questions if this didn't help.

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[campbellsan]

Hi Paul,

Sure, please send it to me. Someone else sent me a similar document a long time ago.

I thought I had put it up on GitHub, but please send me yours anyway, yours might be easier to read.

very best regards,

Derek

On 10 Jan 2014, at 16:30, Paulham [email protected] wrote:

Hi
Thanks for the response. I get it now. I've checked the schematics and I can see that you can only get it to pass signals through with some soldered jumpers!
I have put some tables together to help me understand it all in a Word document - it might help others, should I send it to you? If so, is this the best email address?
Thanks
Paul

On 8 Jan 2014, at 23:29, campbellsan [email protected] wrote:

I have studied the lcd schematic and I can't see how it makes any difference to the Pi whether the connection is direct to the lcd or via the Guzunty CPLD

I started to write a long explanation and realized that I'd probably end up confusing you more. Instead, let me make the following observations about the core design as it currently is:

It supports the daughter card very well.
While it adequately supports wiring an LCD module directly to the Guzunty header pins, the design could probably support this use case better with a bit of work.
Some of the reasoning behind the pin assignments was to avoid having to make too many physical cuts or links to the standard Guzunty board. Now that I return to this after some months, I think the pin assignments could have been done better.
Again, with a bit of work, touch might be possible to support with a daughterless configuration, but JP15 would definitely have to be linked underneath at a minimum, since it must carry the SPI second channel selector signal (and that would have to be routed through the CPLD).
I hope these additional comments help and don't confuse matters further. Basically, the LCD core design isn't perfect, so there isn't necessarily a good answer to every 'why'. The design of the physical routing of the Guzunty board does not have such problems, which is fortunate since they would be much more difficult to fix.

Finally, you were asking about running out of I/O. I think the answer is your latter suggestion; we don't have a shortage of CPLD I/O, but we do start to run into the need to permanently reconfigure the Guzunty PCB. Such reconfiguration begins to compromize the Guzuntys general purpose capability, another reason to just build a daughter card if you want to play with LCD modules.

Do feel free to ask further questions if this didn't help.

—
Reply to this email directly or view it on GitHub.
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Reply to this email directly or view it on GitHub.

[campbellsan]

Closing this issue as part of a site clean up. LCD daughter boards will remain available for as long as there is demand for them.