i have connected a HP12542R-DYO 128x64 parallel driven LCD to my Arduino Mega 2560.
I use this library to control it:http://henningkarlsen.com/electronics/library.php?id=49
Most of the functions are working almost perfect, i can display converted bitmaps on it and also text by using the fonts provided by the library,
but there is a problem with the setpixel function.
This function use bit-manipulation.
A whole page/byte is read from the ram of the lcd, "bit-or'ed" with the new data and finally written back to the lcd.
Every bit which is set results in a black pixel on the display.
The problem is, that my controller think that some bits are set to 1 which are really set to 0.
I tried a shorter cable - no changes.
The D5 have the most problems.
If i touching the isolation of this wire, the readings from the ram seems to be very better.
Touching the wire itself with a metal pair of tweezers fix it completely (but THAT can´t be the solution... ;-) )
I tried to activate the built-in resistors before the reading process by adding the lines ( DigitalWrite(2...9,HIGH) ) to the function for data-direction of the library,
but after that the display showed bullsh... .
Does anybody have an idea how i can fix this issue?
(Sorry for my bad english - i know i have to learn a lot... ;-) )