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GraphLCD driver library

The SED1520 driver
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Description
-----------
The SED1520 driver supports LC displays that use the Epson SED1520
controller, connected to the parallel port of your PC.


Wirings
-------
The SED1520 driver supports the following connection on a parallel
port:

  printerport   LCD          other
  -----------   ----------   ----------
  GND    (18)   GND   (01)   GND          (Ground)
                Vdd   (02)   +5V
                Vo    (03)                (LCD Contrast In -4V)
  nSEL   (17)   R/S   (04)                (Register Select)
                R/W   (05)   GND          (Read/Write)
  nSTRB  (01)   EN1   (06)                (Enable Left)
  D0     (02)   D0    (07)                (DataBit0)
  D1     (03)   D1    (08)                (DataBit1)
  D2     (04)   D2    (09)                (DataBit2)
  D3     (05)   D3    (10)                (DataBit3)
  D4     (06)   D4    (11)                (DataBit4)
  D5     (07)   D5    (12)                (DataBit5)
  D6     (08)   D6    (13)                (DataBit6)
  D7     (09)   D7    (14)                (DataBit7)
  INIT   (16)   EN2   (15)                (Enable Right)
                RESET (16)   +5V          (Controller Reset)
                LED+  (17)   +4V/150mA    (Backlight with 6,4Ohm Resistor to +5V)
  nAUTO  (14)   LED-  (18)   GND          (Backlight GND [via BS170])

  See also http://www.usblcd.de/lcdproc/sed1520-dip.php4 ...

Note: The pin numbering may vary with other displays.


Configuration Parameters
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The SED1520 driver supports the following parameters in config file:

Device
 Instead of using the direct output via port address (see Port), you
 can use the parport device (/dev/parportX). The advantage over the
 direct output via port address is that this works for non-root users
 also. But it's a little bit slower. The modules ppdev.o, parport.o
 and parport_pc.o must be loaded or compiled into the kernel.

Port
 Sets the port address of the parallel port. If this parameter is not
 given, 0x378 is used. To use this direct output, the program that
 uses the driver library has to be started with user 'root'.

Width
 Sets the horizontal size of the display. If this parameter is not
 given, a default value of 120 pixels is used.

Height
 Sets the vertical size of the display. If this parameter is not
 given, a default value of 32 pixels is used.

UpsideDown
 Rotates the display output by 180 degrees. This might be useful, if
 the LCD is mounted upside-down.
 Possible values: 'yes', 'no'
 Default value: 'no'

Invert
 Inverts the display.
 Possible values: 'yes', 'no'
 Default value: 'no'

AdjustTiming
 To get a timing that is as accurate as possible, the drivers measure
 the time for port commands (see: benchmark in syslog). You might
 decrease or increase the time to wait after port commands with this
 parameter. Normally, there is no need to change this parameter.
 Possible values: -50 <= x <= 50
 Default value: 0

RefreshDisplay
 Normally, most of the drivers do not update the whole display, but
 only the areas that have changed since last update. So it might be,
 that some faulty pixels would stay a longer time. To avoid this, the
 plugin makes a complete refresh from time to time. This parameter
 defines how often a complete refresh will be done.
 e.g.: A value of 5 means, that the plugin will make a complete
       refresh on every 5th update.
 A value of 0 completely disables complete refreshs. 
 Possible values: 0 <= x <= 50
 Default value: 5

