The PHY protocol interface (PPI) is the interface between the D-PHY (a high-speed physical layer interface) and the protocol layer. It essentially allows the protocol to communicate with the physical layer for data transmission.
Here's a more detailed breakdown:
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Function: The PPI facilitates the exchange of data and control signals between the D-PHY and the higher-level protocol (e.g., MIPI CSI-2, MIPI DSI). It allows the protocol to control the physical layer, instructing it when to enter low-power mode, high-speed mode, or to switch communication directions (in the case of bidirectional lanes).
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Role: It acts as the bridge allowing the protocol logic to utilize the high-speed capabilities of the D-PHY without needing to manage the intricate details of the physical layer itself.
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Operation: During normal operation, the data lanes controlled through the PPI switch between low-power mode (for power saving) and high-speed mode (for data transmission). Bidirectional lanes, commonly found in some implementations, can also have their communication direction switched via the PPI.
In summary, the PHY Protocol Interface is crucial for enabling seamless communication between a protocol and the physical layer responsible for high-speed data transmission.
