GMZAN3 Datasheet, PDF (33/53 Pages) List of Unclassifed Manufacturers – XGA ALALOG INTERFACE LCD MONITOR CONTROLLER

gmZAN3 Preliminary Data Sheet
DDC
Factory Test Station
Device-Under-Test
Camera
Figure 19.
Factory Calibration and Test Environment
4.5 Input Format Measurement
The gmZAN3 has an Input Format Measurement block (the IFM) providing the capability of measuring
the horizontal and vertical timing parameters of the input video source. This information may be used to
determine the video format and to detect a change in the input format. It is also capable of detecting the
field type of interlaced formats.
The IFM features a programmable reset, separate from the regular gmZAN3 soft reset. This reset disables
the IFM, reducing power consumption. The IFM is capable of operating while gmZAN3is running in
power down mode.
Horizontal measurements are measured in terms of the selected IFM_CLK (either TCLK or RCLK/4),
while vertical measurements are measured in terms of HSYNC pulses.
For an overview of the internally synthesized clocks, see section 4.1.
4.5.1 Horizontal and Vertical Measurement
The IFM is able to measure the horizontal period and active high pulse width of the HSYNC signal, in
terms of the selected clock period (either TCLK or RCLK/4.). Horizontal measurements are performed on
only a single line per frame (or field). The line used is programmable. It is able to measure the vertical
period and VSYNC pulse width in terms of rising edges of HSYNC.
Once enabled, measurement begins on the rising VSYNC and is completed on the following rising
VSYNC. Measurements are made on every field / frame until disabled.
4.5.2 Format Change Detection
The IFM is able to detect changes in the input format relative to the last measurement and then alert the
system microcontroller. The microcontroller sets a measurement difference threshold separately for
horizontal and vertical timing. If the current timing is different from the previously captured measurement
by an amount exceeding this threshold, a status bit is set. An interrupt can also be programmed to occur.
C0523-DAT-01G
33
Genesis Microchip Confidential
http://www.genesis-microchip.com
July 2003