Calculation of OV2640 frame rate

From the timing diagram, the 1-frame time tframe=672*tline, tline = 1190Tp, TP is related to the Sensor register (ff=1) 0x11:

Tp = xvclk/(clkrc[5:0] + 1), XVCLK is the frequency of the external input.

3.1 SVGA Preview, 30fps, 24Mhz input Clock
sccb_salve_address = 0x60;
WRITE_SCCB (0xFF, 0x01);
WRITE_SCCB (0x11, 0x00);
WRITE_SCCB (0x12, 0x40);
WRITE_SCCB (0x2a, 0x00);
WRITE_SCCB (0x2b, 0x00);
WRITE_SCCB (0x46, 0x00);
WRITE_SCCB (0x47, 0x00);
WRITE_SCCB (0x3d, 0x38);

From the above settings, the frame rate can be calculated
Tframe= (1/24000000) *1190*672, frame rate =1/tframe=30.012

3.2 SVGA Preview, 15fps, Mhz input Clock
sccb_salve_address = 0x60;
WRITE_SCCB (0xFF, 0x01);
WRITE_SCCB (0x11, 0x01); XVCLK is divided by two.
WRITE_SCCB (0x12, 0x40);
WRITE_SCCB (0x2a, 0x00);
WRITE_SCCB (0x2b, 0x00);
WRITE_SCCB (0x46, 0x00);
WRITE_SCCB (0x47, 0x00);
WRITE_SCCB (0x3d, 0x38);

The above setting, the input frequency is divided into two, the operating frequency is 12MHz, so the frame rate is reduced by half

3.3 SVGA Preview, 25fps, Mhz input Clock
sccb_salve_address = 0x60;
WRITE_SCCB (0xFF, 0x01);
WRITE_SCCB (0x11, 0x00);
WRITE_SCCB (0x12, 0x40);
WRITE_SCCB (0x2a, 0x00);
WRITE_SCCB (0x2b, 0x00);
WRITE_SCCB (0x46, 0x87);
WRITE_SCCB (0x47, 0x00);
WRITE_SCCB (0x3d, 0x38);

The frame rate is also related to the 0x2a,0x2b, 0x46,0x47 register setting. Setting the 0x2a,0x2b will extend the tline,
such as 0x2a=1, 0x2b=0, then TLINE=1191TP, 0x2a=0, 0x2b=1, Tline = (1190+256) Tp.
Setting 0x46, 0x47 will extend tframe such as 0x46=0, 0x47=1, Tframe= (672+256) *tline,
0x46=2, 0x47=0, Tframe= (672+2) *tline.

The above settings:
Tframe= (1/24000000) *1190* (672+0x87), frame rate = 24.99 Frames

3.4 SVGA Preview, 14.3fps, Mhz input Clock
sccb_salve_address = 0x60;
WRITE_SCCB (0xFF, 0x01);
WRITE_SCCB (0x11, 0x01);
WRITE_SCCB (0x12, 0x40);
WRITE_SCCB (0x2a, 0x00);
WRITE_SCCB (0x2b, 0x00);
WRITE_SCCB (0x46, 0x22);
WRITE_SCCB (0x47, 0x00);
WRITE_SCCB (0x3d, 0x38);

The above settings:
Tframe= (1/12000000) *1190* (672+0x22), frame rate = 14.28 Frames

The calculation of UXGA and CIF frames is calculated according to the timing of the UXGA, and the calculation method is similar.