I have some equipment with a bog standard LCD 16x2.
I built one system up and noticed in one part of the software the display corrupts.
So I checked solder joints etc and it seemed fine.
So removed display and fitted a new one which worked fine.
So bad display ?
I wanted to see if it was software timing problem so soldered bad display into a new pcb.
Now it works fine in the new pcb !
So had a serious look at my software timings and they are all above what spec suggests.
Not sure where to go next ? unless it was a bad solder joint that looked ok ?
I built one system up and noticed in one part of the software the display corrupts.
So I checked solder joints etc and it seemed fine.
So removed display and fitted a new one which worked fine.
So bad display ?
I wanted to see if it was software timing problem so soldered bad display into a new pcb.
Now it works fine in the new pcb !
So had a serious look at my software timings and they are all above what spec suggests.
Not sure where to go next ? unless it was a bad solder joint that looked ok ?
Stick to high quality LCD, which are getting difficult to get, as the Chinese ones are very cheap.
If you find good ones, stock up, quality and supply are erratic.
If you find good ones, stock up, quality and supply are erratic.
Nigel,
I realize you have been at this stuff for a few weeks or more ….! I would suspect a bit of contamination possibly at the joint, the point of attachment to the lcd or even inside at the internal liquid to electrode contact. As it now works, I would rest it on the shelf for a few months to be sure the problem doesn’t creep back.
An old Native American idea ( for some ) was that one should always include a small mistake as only the gods are perfect. Of course we are apparently fortunate to some gods or at least those who believe they are, that assist us on these threadz.
I realize you have been at this stuff for a few weeks or more ….! I would suspect a bit of contamination possibly at the joint, the point of attachment to the lcd or even inside at the internal liquid to electrode contact. As it now works, I would rest it on the shelf for a few months to be sure the problem doesn’t creep back.
An old Native American idea ( for some ) was that one should always include a small mistake as only the gods are perfect. Of course we are apparently fortunate to some gods or at least those who believe they are, that assist us on these threadz.
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It sounds like a data bus problem as lcd would do random things like clear the screen or put up random characters.
Its odd it would power up ok and display first message fine. It even did power up scrolling message ok.
Then when I went to input a number it would start to go wrong.
Now its a bit hard to fix when its working ok.
Can only take it as it comes.
Its odd it would power up ok and display first message fine. It even did power up scrolling message ok.
Then when I went to input a number it would start to go wrong.
Now its a bit hard to fix when its working ok.
Can only take it as it comes.
Ok got to the bottom of it.
Tried a different shift register that sends data to LCD and that fixed it.
So looked up specs for 74hc164 and it needs about 3.1 volts and my PIC is only 3v3 so a 1 is borderline.
Hence working with some 164's and not others.
I should know better as I have ordered hct parts in the past so not sure why current ones are just HC.
Tried a different shift register that sends data to LCD and that fixed it.
So looked up specs for 74hc164 and it needs about 3.1 volts and my PIC is only 3v3 so a 1 is borderline.
Hence working with some 164's and not others.
I should know better as I have ordered hct parts in the past so not sure why current ones are just HC.
Funny, my LCDs are just a display. No other innards.
The current driver might be different because your eyesight is not what it once it was! ( Or maybe the order picker, not just the placer. )
The current driver might be different because your eyesight is not what it once it was! ( Or maybe the order picker, not just the placer. )
I use lcd modules as they are easier to use.
I increased my PIC VDD voltage from 3.3 to 3.5 and the previous none working 74hc164 works now reliably.
My design has now moved to to use a 5 volt PIC so the problem has gone now.
I increased my PIC VDD voltage from 3.3 to 3.5 and the previous none working 74hc164 works now reliably.
My design has now moved to to use a 5 volt PIC so the problem has gone now.