Digilent Pcam 5C 410-358 Manuel de référence - Page 5

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Functional Description

Serial Communication

MIPI CSI-2 Interface

The Pcam 5C includes a dual-lane MIPI CSI-2 interface that is used to transmit image data from the

OV5640 image sensor on the Pcam 5C to the attached host. It consists of three differential pairs,

two for data and one for a clock signal, which are all routed to the 15-pin FFC connector. The clock

and data signals are driven by the image sensor and should be treated as inputs by the attached

host.

The physical layer of the MIPI CSI-2 interface is called D-PHY. It is supported by the I/O blocks on

Xilinx Ultrascale devices natively, but requires some passive circuitry external to the FPGA in order

to be connected to Xilinx 7-series devices. For detailed information on the circuitry required to use D-

PHY with a 7-series device, see the XAPP894 Application Note available from Xilinx.

Further information on the details of MIPI CSI-2 and D-PHY are beyond the scope of this document.

Digilent provides open source MIPI CSI-2 and D-PHY Vivado IP cores that can be studied to learn

more. These IP cores are included in the Digilent Vivado Library.

Serial Camera Control Bus (SCCB)

The SCCB on the Pcam 5C is a two-pin bus used to access the control registers for the OV5640

image sensor. The bus behaves the same way as an I2C bus, and can be treated exactly the same.

This means it can be controlled using existing I2C IP cores or RTL. For a more complete description

of how an I2C bus works, see the I2C Fundamentals Guide.

It is expected that the host provide 1.5 KOhm pull-up resistors on both SCL and SDA. The attached

host drives the clock (SCL) and behaves as the master on the bus. The OV5640 acts as a slave at

the I2C address 0x78.

The register map accessed with the SCCB consists of 8-bit registers organized in a 16-bit address

space. The details of how register read and write transactions occur are detailed in proprietary

documentation that is available from OmniVision. Most users should not need to fully understand

how the SCCB transactions occur, and can instead rely on the libraries included with the Pcam 5C

demo that use the Zynq I2C hardware to properly read and write the OV5640 registers.

Register Details

The registers that are accessed using the SCCB are used to control the OV5640 image sensor. This

includes things such as initializing the sensor, setting the output format, and enabling image

processing features.

The OV5640 image sensor register map is fully documented in the OV5640 datasheet, but Digilent

does not have permission to redistribute that document. To obtain complete information on the

registers, please contact OmniVision and request access to the OV5640 datasheet.