Datasheet
VIPER Embedded Linux Development Kit Quickstart Arcom Embedded Linux (AEL)
Parameter Description Default
hsync and
vsync
Configures the polarity of the horizontal and
vertical sync pulses. A value of 0 indicates an
active low sync pulse, while 1 indicates active
high. These parameters correspond to the
LCCR3[HSP] and LCCR3[VSP] registers.
hsync:0,vsync:0
outputen Configures the polarity of the output enable
signal. A value of 0 indicates an active low
signal while 1 indicates active high. This
parameter corresponds to the LCCR3[OEP]
register.
outputen:1
pixclockpol Configures the polarity of the pixel clock signal.
A value of 0 indicates a falling edge while 1
indicates rising edge. This parameter
corresponds to the LCCR3[PCP] register.
pixclockpol:0
The required values for all of the above parameters are generally defined in the
datasheet for a given LCD panel. Often the timing parameters (pixel clock, margins,
sync pulse lengths) can be derived from values in the datasheet along with a certain
amount of trial and error. It is recommended that you read chapter 7 of the PXA255
Processor Developers manual since many of the parameters given to the driver
correspond directly to settings in the LCD controller hardware.
The default parameters are set to support a TFT type panel, so it is therefore possible
to support another TFT panel by passing only the mode and timings parameters. For
example, to support a 640 x 480 panel such as the NL6448AC20 you would use the
following command:
# modprobe pxafb options=mode:640x480-
16,pixclock:39722,left:16,right:81,upper:12,lower:31,hsynclen:63,vsynclen:2
The options string must be a single line with no spaces or line-breaks.
There is much greater variation between STN type panels, so it is necessary to pass all
parameters. For example, to support a Kyocera KCS057QV1AA-G00 320x240 single
panel color STN display you would use the following command:
# modprobe pxafb options=mode:320x240-
8,pixclock:154000,left:1,right:1,upper:0,lower:0,hsynclen:8,vsynclen:32,passive,c
olor,single,outputen:1,pixclockpol:0,hsync:1,vsync:1
The options string must be a single line with no spaces or line-breaks.
© 2005 Arcom Issue E 27