3graphics interface, 1 lcd/lvds technology overview, Pitx-sp software guide – Kontron pITX-SP User Manual

Page 8: 1 detailed timing descriptor (edid or displayid

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KTD-S0003-C Page

4

Graphics

Interface


p

ITX-SP Software Guide

3

Graphics Interface

3.1

LCD/LVDS Technology Overview

3.1.1

Detailed Timing Descriptor (EDID or DisplayID

TM

)

The input fields Pixel Clock, Horizontal Active, Horizontal Blank, Horizontal Sync Offset, Horizontal Sync
Width, Vertical Active, Vertical Blank, Vertical Sync Offset and Vertical Sync Width must be filled in with the
correct values according to the panel’s data sheet. In many cases the value for Horizontal/Vertical Blank
cannot be read directly from the data sheet. Instead terms such as Display Period (active pixels/lines) or
Horizontal/Vertical Total appear.

In this case the following calculation can be made:

Blank Value = Total Value – Active Value.

Sometimes the datasheet does not specify Sync Offset and/or Sync Width. In this case the permissible
values can only be determined though testing. However the rule is:

The sum of Sync Offset and Sync Width must not exceed the value for Horizontal/Vertical Blank.

Also datasheets are often different for displays with double pixel clock. If Pixel Clock and Horizontal Values
seem to be halved this must be corrected for input:

The values must always be entered as though it were a panel with single pixel clock.

Example 1:

PRIMEVIEW PM070WL4 (single pixel clock)
Data sheet specifications:

Clock Frequency [typ.]

32 MHz

HSync Period [typ.]

1056 Clocks

(equivalent to Horizontal Total)

HSync Display Period [typ.]

800 Clocks

(equivalent to Horizontal Active)

HSync Pulse Width [typ.]

128 Clocks

HSync Front Porch [typ.]

42 Clocks

HSync Back Porch [typ.]

86 Clocks

VSync Period [typ.]

525 Lines

(equivalent to Vertical Total)

VSync Display Period

480 Lines

(equivalent to Vertical Active)

VSync Pulse Width [typ.]

2 Lines

VSync Front Porch [typ.]

10 Lines

VSync Back Porch [typ.]

33 Lines

Result:
Pixel

Clock

32

Horizontal

Active

800

Horizontal Blank

256

((128 + 42 + 86)

→ H. Pulse Width + H. Front Porch + H.

Back Porch)

Horizontal Sync Offset

42

(H. Front Porch)

Horizontal Sync Width

128

(H. Pulse Width)

Vertical

Active

480

Vertical Blank

45

((2 + 10 + 33)

→ V. Pulse Width + V. Front Porch + V. Back

Porch)

Vertical Sync Offset

10

(V. Front Porch)

Vertical Sync Width

3

(V. Pulse Width)

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