ULPI PHY USB 2.0 Link Power Management PID Transmission
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Solution Overview
Problem
Current USB devices with ULPI PHY interface standard cannot support the USB 2.0 Link Power Management Addendum due to the reserved PID value being used for other purposes, preventing them from utilizing power-saving features.
Innovation Solution
Implementing a system that allows ULPI PHY devices to transmit and receive an extended PID token and packets over the ULPI bus, enabling them to support the USB 2.0 Link Power Management Addendum by configuring the ULPI transceiver to initiate data transfers with a reserved PID code and qualifying it with a function control code, allowing normal operation and transmission on the USB bus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the reserved PID value is used for ULPI Chirp transaction, then the ULPI PHY interface can maintain simplicity and backward compatibility, but the USB 2.0 Link Power Management Addendum cannot be supported
Solution Approach 1:
The ULPI PHY device dynamically changes its operation mode based on the function control code received. When in normal operation mode, it transmits the reserved PID value followed by qualified data. When in bit-stuffing and NRZI encoding disabled mode, it transmits only the qualified data without the reserved PID value. This dynamic behavior allows the same interface to support both USB 2.0 Link Power Management and ULPI Chirp transaction protocols.
Solution Approach 2:
The invention changes the transmission parameters based on the function control code. The presence or absence of the reserved PID value in the transmission stream is controlled by the operation mode. This parameter change allows the interface to adapt between different protocol requirements without hardware modification.
2Use of energy by moving object
If the ULPI PHY transmits the reserved PID value for LPM extended transaction, then power-saving features can be enabled, but conflict with ULPI Chirp transaction usage of the same PID value arises
Solution Approach 1:
The ULPI PHY device receives preliminary control information (function control code) that indicates the intended operation mode before transmitting data. Based on this preliminary information, it prepares the appropriate transmission format - either including the reserved PID value for LPM extended transactions or excluding it for ULPI Chirp transactions - ensuring protocol compatibility is maintained in advance.
Solution Approach 2:
The function control code acts as an intermediary that mediates between the USB Link and ULPI PHY device, indicating whether to use normal operation mode (with reserved PID value for power management) or bit-stuffing and NRZI encoding disabled mode (without reserved PID value for Chirp transactions). This intermediary control mechanism resolves the conflict between the two protocols.
Data Source
AI summary
A protocol may enable support of the USB 2.0 LPM (Link Power Management) Addendum by a ULPI PHY (Universal Serial Bus Transceiver Macrocell Low-Pin Interface Physical Layer Device), facilitating transmitting the reserved PID (Physical Interface Device) token, used in the LPM Extended Transaction, through a ULPI bus. Bits [3:0] of a ULPI Tx Cmd (Transmit Command) byte may be reused, with the value of those bits being 4′b0 for a transmission (normally indicating a No PID transmission), by configuring the ULPI PHY to qualify the selected four Tx Cmd bits (bits [3:0] of the Tx Cmd) with the Opmode code. The ULPI PHY may thereby interpret bits [3:0] of the Tx Cmd byte based on the value of the Opmode, and may not transmit the Extended PID when the Opmode is set to 2′b10, that is, when the Opmode is indicative of bit-stuffing and NRZI encoding being disabled, for example during a Chirp transmission. When the Opmode code is set to 2′b0, indicative of normal bit-stuffing, and the Tx Cmd bits [3:0] are set to 4′b0 during a transmission (Tx Cmd bits[7:6]=2′b01), then the PHY may transmit the Extended PID, followed by the rest of the extended transaction onto a USB.