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Unstable character display


#1

I am having a Spider mainboard, newest firmware, and the character display (HD44780 module from GHI). Nearly all sockets are full of modules, including T35, J11D and more.

The character display works most of the time, but sometimes it just goes into a bad state, all characters are move to the right, or it goes into a REALLY bad state where everything is messy and does not look like characters.

I have seen other user mess with the driver, and I have tried adjusting the sleeps to be slightly longer, but it does not stabilize it.

Any ideas?


#2

Hard to say. I would try to narrow it down. Try without any other modules. Try on different Y socket. Etc.


#3

with almost every socket in use could it be a power issue?


#4

IIRC, the display uses the 5v power so yes power could be the issue.


#5

I am using external power supply, power shouldnt be the issue. I am still really wondering what can cause these obfuscated letters.

I am thinking multithreading, should I encapsulate acces to the display?


#6

If you access display from different threads, then you have to make sure it is thread safe.


#7

Thanks, I learned it the hard way. Making sure the display is only accessed from one thread did the trick. It is a really slow display, so the probability for cross accessing is big.

When is the next generation of the character display due?

Is thread safety not built into the drivers?


#8

I do not think it is thread safe