Line_VALID timing from D5M camera

Hi guys,

I am using the demo code of D5M on DE2-115. And I didn't change the camera settings in I2C_CCD_Config, in which Width = 800, HBMIN(horizontal blank) = 500, PIXLCLK = 50MHz.

So the length of Line_VALID signal should be 800 + 500*2 = 1800, correct?

But when I monitored the signal of Line_VALID，I found that:

time Line_VALID = 1 is 16 us, which equals 800 pixels. This is meaningful

but time Line_VALID = 0 is about 31.1 us, which equals around 1555. But I though it should be 2*HBMIN = 1000.

Can you tell me which part is wrong? Thanks very much!

BTW: The default settings for D5M camera are:

EXTCLK (MHz) 50

Col_Bin 1

Row_Bin 1

Col_Skip 1

Row_Skip 1

Col_Size 1599

Row_Size 1199

Shutter Width (SW) 1984

Horizontal Blanking 0

Vertical Blanking 25