40x4 HD44780

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I'm having a bit of trouble controlling a 40x4 lcd[using mega128]. . .when writing to any given line, I make sure to enable(+5) the appropriate E line and disable(Gnd) the other. . .if/when it works, it will display data for a while(maybe a few power cycles at most) then only one side of the LCD will display data while the other will be just random(to me anyways) data(typically "?" on one line). . .I'm running at 16MHz and I'm certain I can get [any] one side to work, but when trying to switch between them, I get no love. . .
one troubleshooting technique I did was switch my defines so that E1 becomes E2 and vice versa and all of a sudden both will come up[but back to what I mentioned above: for a little bit and then it will take me back to where I started. . .one side till I switch the defines again]. . .I'm thinking it's in the way I'm switching between the E lines. . .I ground the E line of one display, then enable the other to write to that particular lcd?. . .is there any special sequence other than turning one off before turning the other on, to get these to work[regularly]? Any suggestions would be much appreciated. . .

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Can you post a schematic and a photo of your setup ? And the software of course.

Nard

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a 40x4 module has 2 44780 controllers on it. So you need to initialise both of them. Basically it's two 40x2 displays in one package (one glass of course).