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Missing pixles CFAG240128LYYHTZ


New member

I'm having problems with my CFAG240128LYYHTZ. I've wired many of the mentioned lcds on various pcbs. This last one is causing me headaches. LCD is working ok (I tried it on other board), but when I connect it to my new board, some weird missing pixels occur. I will try to take a pic of the screen, but until then, I'd really appreciate if you guys could give me some pointers on what else to check. I've exhausted my options :)

My pcb has:
- Isolated DC 5V voltage. Very stable, not much noise there.
- Good ground
- microcontroller <-> LCD traces are shorter than 1 cm, >= 10 mils.
- I have 100nf and 10 uF (tried 22 uF, no diff) capacitor near lcd power supply (pins 1,2,3)
- I have 100 ohm resistor in series of LCD CE line. Measured with oscilloscope, the CE line is clean.
- I have 100 nF to ground on LCD RESET.

Hope to get some ideas.. :)


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... what else to check. I've exhausted my options
Possibly a timing issue? Write/read pulse widths enough greater than minimum so not to be marginal, setup time for data is adequate, etc. All these are code related items, so if the code hasn't changed, it should work OK. If you have a scope, you could write a test loop to put the same data to the screen repetatively, and look at the waveforms to see what the actual timing of the status check, data write, etc. to see if it conforms to the timing minimums. Do all your measurements at the input pins of the LCD to include the effects of possible poor connections.

Without a scope, you could just try making your timing values longer (i.e. add delays) between steps, to see if it changes the symptoms.