402-00005-00
Registers
3–28
Rev 02; February 8, 2002
3.4.1.2 Horizontal Sync End (HESYNC) R/W
HESYNC defines the Programmable Timing Generator (PTG) horizontal sync pulse duration. The 8-bit value is the
number of pixel clocks the horizontal sync pulse (Hsync) is low.
The Hsync pulse time for RS170 is 4.7 us. The Hsync pulse time for CCIR is 4.7 us. The pixel clock time varies from
50 to 100 ns based on the number of samples per line.
Use the following formula for calculating HESYNC:
HESYNC = (Hsync pulse time (ns) / pixel clock time (ns) ) – 1
HESYNC
Function
0
hsync low = 1 pixel clock
1
hsync low = 2 pixel clocks
2
hsync low = 3 pixel clocks
3
hsync low = 4 pixel clocks
. . .
. . .
255 (0xFF)
hsync low = 256 pixel clocks
3.4.1.3 Horizontal Sync Output Polarity (HSYNCPOL) R/W
The HSYNCPOL bit defines the polarity of the horizontal sync signal driven out onto the camera connectors, in
internal timing mode (XTAL). HSYNC is used internally in XTAL mode, and always available (driven) if XTAL
mode is enabled.
HSYNCPOL
Function
0
Hsync is active low
1
Hsync is active high
3.4.1.4 Internal Timing Horizontal Sync Polarity (XTALMDHPOL) R/W
This bit only affects the PTG Hsync input to the PWG, and does not affect the signals output to the camera interface,
or any other timing circuits. This bit gives additional flexibility to programming the PWG with cameras that respond
slowly to the Hsync from the PCVisionplus.
XTALMDHPOL
Function
0
Normal operation
1
Invert Hsync into PWG
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