ADE3800SXT datasheet(36/138 Pages) STMICROELECTRONICS

Part #	ADE3800SXT

Description	Analog LCD Display Engine for XGA and SXGA Resolutions with Embedded LVDS and RSDS Transmitters

PDF	138 Pages

Scroll/Zoom	100%

Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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ADE3800

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4.7

Input Sync Measurement (SMEAS)

The SMEAS block monitors input activity and measures input sync signals from all sources. All

unused and reserved bits return as zero. SMEAS operates in the crystal clock (xclk) domain.

Input Sync Functions:

● Activity Detection: detects input activity

● Measurement: measures sync period and width

4.7.1

Input Sync - Activity Detection

The activity block measures all sync sources in parallel. An active channel is defined as having a

programmable number of rising edges within a programmable number of xclk cycles (= sample

period). Activity limits are set per channel class: clkdiv1k and HSync; vsync. The activity results are

updated each sample period.

Software can select either:

● One shot: one time measurement

● Free Run: continuously running measurements

Figure 7: VSync Up/Down Counter

Composite

Sync

H Pulse

V Pulse

1/8

1/4

3/4

7/8

Threshold

DOWN

OK: good

if V Pulse width was too short for the chosen threshold

(counter reaches 3/4th but goes down before 7/8th is reached):

Bad sync bit SRT_VS_SEL[3] would be set

threshold

Extracted

VSync

up at 7/8

down at 1/8

BAD SYNC AREA

error

ADE3800SXT Datasheet(PDF) 36 Page - STMicroelectronics