In the realm of camera technology, DVP, or Digital Video Port, is a significant interface type used in various camera modules. It is primarily a parallel interface used for transmitting video signals from a camera sensor to a processing unit. This interface is commonly found in cameras used in surveillance systems, robots, security systems, and other embedded systems. DVP interfaces are known for their simplicity and robustness, making them suitable for a wide range of applications.
The working principle of a DVP interface involves several key signals and components:
AVDD: Analog power supply for the camera sensor's analog components.
IOVDD: Power supply for the camera's GPIO (General-Purpose Input/Output) pins.
DVDD: Digital power supply for the camera's digital signal processing components.
PWDN (Power Down): Enables or disables the camera. When set to standby, all operations on the camera are invalid.
RESET: Resets the camera to its factory default state. This is a hardware reset.
XCLK (External Clock): Provides the working clock for the camera sensor.
PCLK (Pixel Clock): Synchronizes the pixel data output.
VSYNC (Vertical Sync): Indicates the start of a new frame.
HSYNC (Horizontal Sync): Indicates the start of a new line within a frame.
DATA[0:11]: The data bus, which can be 8, 10, or 12 bits wide, depending on the ISP or baseband support.
The camera sensor captures light through its lens and converts it into electrical signals. These signals are then processed internally and converted into digital signals. If the sensor does not have an integrated DSP (Digital Signal Processor), the raw data is transmitted via the DVP interface to the baseband or processing unit. If a DSP is integrated, the raw data undergoes further processing such as AWB (Auto White Balance), color correction, lens shading correction, gamma correction, sharpness enhancement, AE (Auto Exposure), and de-noising before being output in YUV or RGB format.
Advantages:
Simplicity: DVP interfaces are relatively simple and straightforward to implement.
Wide Availability: They are commonly found in many embedded systems and surveillance cameras.
Cost-Effective: Generally less expensive compared to other interfaces.
Limitations:
Speed and Resolution: DVP interfaces have limitations in terms of speed and resolution. They are typically suited for lower resolution cameras. The maximum PCLK rate is around 96 MHz, with a recommended maximum rate of 72 MHz to ensure signal integrity.
Signal Integrity: The parallel nature of the interface makes it susceptible to noise and interference over long cable lengths.
Speed and Resolution: MIPI interfaces are capable of supporting higher resolutions and faster data rates, making them suitable for high-end cameras in smartphones and other devices.
Signal Integrity: The serial differential signaling used in MIPI interfaces provides better noise immunity and allows for longer cable lengths compared to DVP.
Complexity: MIPI interfaces are more complex to implement and require more sophisticated PCB layout and impedance control.
DVP is a robust and cost-effective camera interface suitable for a wide range of applications, particularly in surveillance, robotics, and security systems. While it has limitations in terms of speed and resolution, its simplicity and wide availability make it a popular choice for many embedded systems.
