Dear Kai,

You said "Have a look at actual datasheet of LCD. Very probably you will find specification of max rise time and max fall time of enable signal to be smaller than 25nsec."

Yes, it is true for the HD44780 chip. In such cases if the rise time or fall time is slower than specified, then maybe the relevant pulse will be missed at the concerned input. Question is, what is the reason for such a specification ? What kind of input structure will impose such a condition ?

Thanks

Raghu