to OmniVision Technologies, Inc. Version 2.21, August 24, 2006

　　OV7949 CMOS NTSC/PAL (OmniPixel®) CAMERACHIP™ Sensor Omni ision

　　The receiver must pull down SIO_D during the

　　acknowledgement bit time. During the write cycle, the

　　OV7949 device returns the acknowledgement and, during

　　the read cycle, the master returns the acknowledgement,

　　indicating to the slave that the read cycle can be

　　terminated. Note that the restart feature is not supported

　　here.

　　Within each byte, the MSB is transferred first. The

　　read/write control bit is the LSB of the first byte. Standard

　　SCCB communications require only two pins, SIO_C and

　　SIO_D. SIO_D is configured as an open drain for

　　bidirectional purposes. A HIGH to LOW transition on the

　　SIO_D while SIO_C is HIGH indicates a START condition.

　　A LOW to HIGH transition on the SIO_D while SIO_C is

　　HIGH indicates a STOP condition. Only a master can

　　generate START/STOP conditions.

　　Except for these two special conditions, the protocol that

　　SIO_D remain stable during the HIGH period of the clock,

　　SIO_C. Each bit is allowed to change state only when

　　SIO_C is LOW (see Figure 4 and Figure 5).

　　The OV7949 SCCB interface supports multi-byte write

　　and multi-byte read. The master must supply the

　　sub-address in the write cycle, but not in the read cycle.

　　Therefore, the OV7949 takes the read sub-address from

　　the previous write cycle. In multi-byte write or multi-byte

　　read cycles, the sub-address automatically increment