On 26/08/2013 09:41, Denis Maros wrote:
Yes, i'm talking about 2*20 character LCD display connected to 24 pin
parallel port on motherboard.
I've tried to access this device simply via this command:
# echo "Test" > /dev/lpt0
ksh: cannot create /dev/lpt0: Device busy
Yeah, failed.
Do you suggest any other method/code to try if /dev/lpt0 accessable?
I had thought that a driver would be needed cause the vendor had Linux and
FreeBSD driver included in CD.
By the way that the vendor is Lanner INC and device is FW-7581A.
I suspect an LCD module is unlikely to work while driving it as if it
were a parallel port printer. The issue is the protocol. A printer uses
the Centronics interface e.g.:
<http://retired.beyondlogic.org/epp/epp.htm>
LCD modules vary, but tend to use some variation of the following:
<http://www.newbiehack.com/MicrocontrollersABeginnersGuideIntroductionandInterfacinganLCD.aspx>
For one thing, an LCD module has commands (to set the mode, clear the
display, configuration etc) - it doesn't just take ASCII characters.
Using the parallel port however is often just a convenient way of
getting some logic-level signals in and out... but you're probably going
to need to bit-bang them (i.e. control them individually) yourself,
rather than using a parallel-port protocol.
HTH,
Steve
