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Topics - hvilleneuve

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OLEDs / Precision about Vih in NHD-0420DZW-AY5 specifications
« on: July 31, 2015, 02:12:19 PM »
in the specifications for NHD-0420DZW-AY5, it is stated that Vih (min) = 0.9VDD.

If we are powering the LCD from VDD=+5V, it means that Vih should be higher than +4.5V, which is extremely high.

It seems to be an error. Can you confirm the minimum Vih when VDD=+5V

OLEDs / NHD-0420DZW-AY5 with scrambled display
« on: July 30, 2015, 02:32:59 PM »
We are using a NHD-0420DZW-AY5. The display works fine, but after a few hours/days of operation, we sometimes observe that the the display is full of strange symbols. Those symbols are not part of the listed characters in any of the ROM character tables in the datasheet. Even if we restart the software and reinitialize the LCD, we cannot recover from this condition. The only solution seems to remove and then reapply the +5V supply.

If we reinitialize the CGRAM data, it doesnt change anything either.

During our initialization sequence, we always write 10 characters and check after each of them that the auto-incremented address reported by the LCD is valid. This test passes with success during this scrambled mode. So the LCD is responding correctly to the HOST commands, but it seems that its character table is somewhat invalid.

The timing has been verified on an oscilloscope, and all signals are well within the specified ranges.

We have seen this behavior in at least three of our products, so this has not happened on a single LCD.

Any idea?

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