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Display

This describes the display-driver of the XScale-based Trizeps-modules. The parameters for the display are read in this order ( parameters read later overwrite earlier values):

  1. BootBitmap
  2. [HKEY_LOCAL_MACHINE\Drivers\Display\Default]
  3. If a BootBitmap has not been loaded, [HKEY_LOCAL_MACHINE\Drivers\Display\Default\displayname]; where displayname is defined with [HKEY_LOCAL_MACHINE\Drivers\Display\Default] Name.

The registry-settings are found in the display.reg.

Registry-Key may vary depending on Trizeps-module and OS-version!

Registry Keys

Common to all Trizeps-Modules

[HKEY_LOCAL_MACHINE\Drivers\Display\Booted Display]
Key Type Description
Name STRING Key holding the actual booted display (not the one to be booted!).
[HKEY_LOCAL_MACHINE\Drivers\Display\Default]
[HKEY_LOCAL_MACHINE\Drivers\Display\displayname]
Key Type Description
Name STRING Defines the name of the display, which parameters are to be used (Only in \Default).
DisableBootPars DWORD If set to 1, ignore the BitmapBoot-parameters.
CxScreen DWORD Horizontal-resolution.
CyScreen DWORD Vertical-resolution.
DisplayOn DWORD GPIO which turns the display on/off.
DisplayOnPol DWORD Polarity of DisplayOn-GPIO.
BufferStrength DWORD BufferStrength of the display-lines (PXA270: 0..15; PXA320: 1..7; PXA168:0..3).
Angle DWORD Angle ( 0, 90, 180, 270) with which the display starts.
Angle2 DWORD Alternative Angle (0, 90, 180, 270) used by RotateScreen-applet.

Trizeps 2,3,4 and 5

[HKEY_LOCAL_MACHINE\Drivers\Display\Default]
[HKEY_LOCAL_MACHINE\Drivers\Display\displayname]
Key Type Description
Name STRING Defines the name of the display, which parameters are to be used (Only in \Default).
Bpp DWORD Color-depth ( 4, 8, 16).
Control0 - Control3 DWORD Contain display parameters. See Intel/Marvell PXAxxx Developers Manual.
EraseFrameBufferOnStart DWORD If set to 1, clear the framebuffer on start (black screen).
SuspendColor DWORD Clear the framebuffer with this color, before going into suspend.
UseInternalSRAM DWORD If set to 1 uses internal SRAM for framebuffer. If framebuffer is to big, this could split the framebuffer (internal SRAM and SDRAM). This might be a problem for application that directly access the framebuffer, i.e. DirectDraw.
DisableOutput DWORD Disables output of display signals.

Trizeps 6

[HKEY_LOCAL_MACHINE\Drivers\Display\Default]
[HKEY_LOCAL_MACHINE\Drivers\Display\displayname]
Key Type Description
Bpp DWORD 
 Valid values: 12,16,18,24.
 Selects number of display-lines to use.
BaseFramePixelFormat DWORD 
 Selects Pixel-Format used for framebuffer:
 4: RGB565 (16Bpp)
 8: RGB8880 (24Bpp)
ClockDivider DWORD 
 See Marvell PXA168 Developers Manual.
 Typical this is set to (0x80000000 | divider);
 where divider = 312MHz / PCLK-frequency.
HBackPorch DWORD Horizontal Back-Porch in Pixel-Clks
HFrontPorch DWORD Horizontal Front-Porch in Pixel-Clks
HSyncWidth DWORD Horizontal Sync-Width in Pixel-Clks
VBackPorch DWORD Vertical Back-Porch in Line-Clks
VFrontPorch DWORD Vertical Front-Porch in Line-Clks
VSyncWidth DWORD Vertical Sync-Width in Line-Clks
SyncPolarity DWORD 
 See Marvell PXA168 Developers Manual (LCD_SPU_DUMB_CTRL).
 0x02  : Pixel-Clock-Polarity ( 0: falling edge, 1: rising edge)
 0x04  : HSync-Polarity ( 0: active high, 1: active low)
 0x08  : VSync-Polarity ( 0: active high, 1: active low)
 0x10  : DENA-Polarity  ( 0: active high, 1: active low)

See Also

BitmapBoot Tool,
Connect a Display to a Trizeps,
Connect a LVDS Display to a Trizeps

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