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Broken STM32 pin to LCD

 

A friend of mine built a rev. 2 QMX, but had a few problems and gave it to me to troubleshoot it. I was able to get it to power up, flash firmware, change settings from the terminal interface, but the LCD text was corrupted. I traced the problem down to data pin 2 on the LCD interface being stuck low, which I found was due to pin 1 on the STM32 being broken. At some point I may have another friend take it into work and try some tiny detail soldering, but the pin is broken off almost flush with the package, so he is doubtful that he will be able to get it to work.
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My understanding is that the Hitachi LCD driver chip on the screen supports a mode that sends data 4 bits at a time using only the upper 4 bits of the data bus. Would it be possible to get a firmware version that uses that mode? Or perhaps just a firmware that would allow remapping that signal somewhere else where it would be easier to bodge? Or does anyone have any other ideas?
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Thanks and 73,
Hudson, KL4LJ
 

Hudson, early firmware Versions did use 4 bit. At least good for a Test.
73 Ludwig
 

Ludwig,
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Many thanks; that worked. Certainly not perfect, but good enough to do further testing.
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73,
Hudson, KL4LJ
 

Howdy, this is my QMX.
I suppose this is more of a request for Hans: might it be possible for you to make a special version of the current firmware that uses this mode?
 

Hi James

I can add a configuration parameter in the next firmware version which allows you to choose 4-bit mode. But remember that:
  • 4-bit mode is half the speed of 8-bit mode (though nobody complained of slowness in earlier firmware versions)
  • Future firmware features may depend on speed (available through 8-bit mode) and/or on other aspects of LCD functions or exploits that are only available?in 8-bit mode.?
73 Hans G0UPL



On Wed, Sep 18, 2024 at 4:45?AM James Ervin via <ervinhfamily=[email protected]> wrote:
Howdy, this is my QMX.
I suppose this is more of a request for Hans: might it be possible for you to make a special version of the current firmware that uses this mode?
 

Howdy Hans,
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Thank you so much for the tweak; I really appreciate it!
I'm curious, what would/could be added that would require the 8-bit mode?
 

Hello James
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Thank you so much for the tweak; I really appreciate it!
I'm curious, what would/could be added that would require the 8-bit mode?

I have some ideas I wanted to try but I consider them "stretch goals" and so so far out that I don't want to put them on paper (or electronic equivalent) until I am way past much higher priority things and until I have experimented a lot and know what's possible; so perhaps nothing may ever come that requires 8-bit mode, perhaps it may, I don't know yet.?

The other thing is speed, it takes twice as many write operations to transfer the data in 4-bit mode compared to 8-bit mode. Right now there is nothing that requires higher speed but the 8-bit write mode does make things faster overall and something may benefit from that in future.?

73 Hans G0UPL

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