[Icc-avr] 4-line LCD display

[Johan H. Bodin]

Albert vanVeen wrote:
> We tried the hardware suggestions, and I experimented with various
> timings.
> It appears that around the christmas break we changed supplier, and now
> we're havinf this strange behaviour of about 2 in 5 units failing.

Hi Albert,

 From my own experience with the HD44780 (and work-alike chips), I know that the 
E clock signal must have very fast rise and fall times. A weak driver in 
combination with a long cable *will* cause trouble...

Hitachi's HD44780 data sheet specifies 25ns maximum rise/fall times on the E signal!

To find out if this is the problem, you can try a non-inverting schmitt trigger 
in the E line, close to the LCD module. Two 74HC14 inverters in series will do 
(or a single one if you invert the E signal in the software).

Regards
Johan Bodin