VIPER Detailed hardware description
LCD logic supply enable
The PXA255 GPIO10 pin controls the supply voltage for the LCD Logic. When GPIO10
is set to logic ‘1’, the LCD supply LCDSAFE is supplied with 3.3V (turned on). See the
section PL3 – LCD connector
, page 62, for PL3 pin assignment, connector and mating
connector details.
This may be factory configured (using a surface mount resistor) to supply 5V. If
the flat panel logic is powered from 5V, it must be compatible with 3.3V
signaling.
LCD backlight brightness control
The control of the backlight brightness is dependant upon the type of backlight inverter
used in the display. Some inverters have a ‘DIM’ function, which uses a logic level to
choose between two levels of intensity. If this is the case then GPIO16 (Alternative
Function 0) is used to set this. Other inverters have an input suitable for a pulse-width
modulated signal; in this case GPIO16 should be configured as PWM0 (Alternative
Function 2).
STN BIAS voltage
The VIPER provides a negative and a positive bias voltage for STN type displays. The
negative and positive bias voltages are set to –22V and +22.5V respectively. Pin
connections for these can be found in the section PL3 – LCD connector
, page 62.
Please contact Arcom for details of other bias voltages. Contact details are provided in
Appendix A – Contacting Arcom
, page 72.
Do not exceed 20mA load current.
© 2004 Arcom Issue H 32
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