MODE_720P_1280_720_60fps works only in 30fps

[Udi FPGA]

Hi 

I'm working on the Zybo -Z7-20 Pcam 5c project.

when I use MODE_720P_1280_720_60fps I saw that the image sensor only generate 30 fps. the HDMI works at 60fps.

I found the Vsync & Hsync from the image sensor (video_tlast & video_tuser) and sew that a cycle (frame) takes about 30mSec (30fps).

for 60fps it should be 16mSec.

I changed the the PLL multiplication to 120 (reg 3036 0x78) and the HTS to 1840 (Reg 380c/d) & VTS to 980 (Reg 380e/f). but I could only get about 50 fps from the image sensor.

I reduced the resolution to 640 x 480 (I wrote a new config_word_t) and I could see that in this resolution I can get 60fps.

how can I get 60fps from the image sensor in 1280x720 resolution?

Thanks 

    Udi