The E line of the the LCD module is effectively a 'device enable'.
When not enabled, it ignores everything on the input pins so you
should have no trouble multiplexing the pin functions.
If you are not reading back anything (e.g. busy status or cursor info)
you can tie the R/W line to write mode as well and know that the
device will never drive the pins.
R
louis frias wrote:
{Quote hidden}> I need suggestions .. I would like the time share the 4 I/O lines needed to
> interface
> to an LCD module HD44780 in the 4 bit mode …and be able to multiplex a cross
> point
> 3x4 or 4x4 switch key board in a similar manner as I do with multiplexed 7
> segment
> LEDs. I only need 10K and a 100k isolator resistors to be able to do a quick
> kbd mux
> scan between 4 digit plexes. I understand that the 4 bit LCD module I/O line
> are tristatable.
> I can not find any were a clear indication if the E (enable) line of the LCD
> module will
> allow me to do a quick scan of common connected switch matrix to these 4 bit
> I/O lines
> in a manner that it will not interfere with the switch scan or the LCD
> module itself.
> Any suggestions ?????????????????? .....louiKILLspam
@spam@g2a.net
