Double characters and screen dimming on NHD-0220AZ-FL-YBW
Hello,
I'm using the NHD-0220AZ-FL-YBW, 8bit, 1-line mode, and having a strange problem in my application. I have the display working fine with arduino. When used in my application, it can work to display all characters and responds to each command that I expect, but there are two glitches that I'm struggling with:
1) With some strings, it will double a character. Always the same characters for the same strings. For example "Please select: " will always show as "Pleasee selecct: ". This is repeatable for the same characters in the same strings every time, but not all strings. In fact, I can't distinguish any trend or correlation to any pattern. When I monitor the signals on an oscilloscope, I can count and confirm that my application sends the correct number of latches, so it must be something on the display. However, I can print the same string using arduino with no problem, so I recognize it could also be an interaction with my application.
2) Occasionally, with some strings (the same ones each time) will make the screen dim (black letters go gray), and it persists as if it is "stuck". When this happens, the cursor shifts slightly higher. Also when this happens, sometimes the next string of characters are junk, until I clear the display again. I found I can "fix" the dimming by writing certain characters, and it will dim again for others. For example, when I write an "8", the screen always dims and persists that way, then when I write a "5", it comes back. This behavior is repeatable and not random (the same as problem (1) above)
Is it possible that certain bytes are being sent that are scrambling the display's normal operation? Any thoughts or ideas are truly appreciated.
Thanks so much,
Michael Terranova
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Hi Michael,
Sorry to hear that you are experiencing issues with the display. It may be necessary to adjust the execution time to resolve the problem of double characters appearing on the screen.
For screen dimming, have you tried swapping to a second display to see if the issue persists? Also, could you please confirm if the problem is still noticeable when testing with the Arduino? Additionally, it would be helpful if you could provide information on the supply current and voltage being provided to the display. Lastly, could you please share a picture of the backside of the display that is not functioning properly?
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