Frequently Asked Questions

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could not initialize parallel port

If your parallel port display does not work, please run lcd4linux -Fvv and have a look at the output. if you get these messages:

HD44780: using ppdev /dev/lp0
HD44780: ioctl(/dev/lp0, PPCLAIM) failed: 22 Invalid argument
HD44780: could not initialize parallel port!
HD44780: start display failed!

then you did not read the documentation, because there it reads:

Note that you have to use parport devices (usually /dev/parports/* or /dev/parport* with major number 99), the printer devices (/dev/printers/* or /dev/lp* with major number 6) do NOT work!

So you have to change your lcd44linux.conf and replace the Port '/dev/lp0' with Port '/dev/parports/0'

If you don't have that you'll need to create it first with 'mknod /dev/parport0 c 99 0'.

Parallel port Permissions

// not approved yet // Of course, you have to had permission to use /dev/parport0 For some reason, changing the permission with chmod do not hold after a restart on some distribution. Instead, you should just make sure the user that runs the program is in the lp group.// not approved yet //

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