ov7620 OmniVision Technologies, Inc, ov7620 Datasheet - Page 24

• Manufacturer Part Number: ov7620
• Description: Single-chip Cmos Vga Color Digital Camera
• Manufacturer: OmniVision Technologies, Inc

OV7620/OV7120 Product Specifications - Rev. 1.2 (7/10/01)
0.8 Slave Mode Operation
OV7620/OV7120 can be programmable to be slave device. Default OV7620/OV7120 is a master
device, it provide Hsync, Vsync output. If used as slave device, (register 29 bit 6=1), external
master device must provide:
When in slave mode, OV7620/OV7120 tri-state CHSYNC and VSYNC output pin and use as in-
put pin. To synchronize the chip, OV7620/OV7120 use external system clock CLK synchronize
external horizontal sync Hsync, then use synchronized horizontal sync to synchronize external
vertical frame sync Vsync. But to match internal counter, these three must keep exact relation as
below:
OV7620/OV7120 will be stable after 1 frame. (2nd Vsync).
0.9 Frame Exposure Mode
OV7620/OV7120 support frame exposure mode when in Progressive Scan Mode. When the
FREX pin is used as an external master device sets the exposure time. When FREX =1, the
whole array is precharged. The exposure time is then determined by the external master device
which controls FREX. When FREX=0, the OV7620/OV7120 begins to output data line by line.
While data is output, the OV7620/OV7120 must be blocked from light by using a mechanical
shutter, so that the whole array is exposed at the same time and has the same exposure period.
In default line exposure mode, the array precharge and read mode is first charge 1st line, after
one line read out, precharge 2nd line, so on. the width of FREX=1 must large the a fixed timing
to make sure whole array has been precharged.
System clock CLK to XCLK1 pin;
Horizontal sync Hsync to CHSYNC pin, positive acted.
Vertical frame sync Vsync to VSYNC pin, positive acted.
Hsync period is 2*858 * CLK
Vsync period is 525* 2*858 * CLK
CLK
Hsync
Vsync
1 line=2*858*Tclk
Note: (1) Ths > 6*Tclk (2) Ths < Tvs < 2*858*Tclk
FIG 0.5 Slave Mode External Sync Timing
1 frame = 525*2*858*Tclk
Tclk
Ths
Preliminary
Company Confidential
OMNIVISION TECHNOLOGIES INC.
Tvs