In-Band Control Interface for Serial Bus Initialization
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Solution Overview
Problem
High bandwidth serial user interfaces for connecting peripheral devices to computing devices, such as touch displays and cameras, face challenges in achieving low power and high performance due to reliance on out-of-band control interfaces, which increase costs and require additional software infrastructure.
Innovation Solution
Implementing a high speed asymmetric interface initialization scheme where the host processor remains the master, enabling an in-band control interface that eliminates the need for additional control interfaces, reduces pin counts, and utilizes MIPI DPHY low power mode and ultra-low power states to conserve power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an out-of-band control interface is used for interface initialization, then the interface can be initialized, but system costs increase and additional software infrastructure is required
Solution Approach 1:
The patent merges the control interface functionality into the existing data interface by using the data lanes for both data transmission and control signaling. The host controller uses the same physical interface (MIPI CSI-2) that the peripheral device uses for data to also carry control commands and responses, eliminating the need for a separate control interface and reducing overall system complexity.
Solution Approach 2:
The data interface is made multi-functional by enabling it to handle both data transmission and control operations. The host controller can issue control commands (such as initialization, configuration, and status queries) over the same data lanes used for high-speed data transfer, allowing a single interface to serve multiple purposes.
2Reliability
If an out-of-band control interface is used for interface initialization, then the interface can be initialized, but pin counts increase and board routing cost increases
Solution Approach 1:
The control signaling is combined with the data transmission signaling, allowing both control and data to share the same physical pins and routing. This eliminates the need for additional dedicated control pins and reduces board routing complexity.
3Reliability
If traditional initialization methods are used, then the interface can be initialized, but power consumption increases
Solution Approach 1:
The initialization process uses a structured sequence of control commands and responses transmitted over the data interface, allowing the system to initialize efficiently and then transition to low-power states. The control interface enables precise timing and state management, allowing the peripheral device to enter ultra-low power states between data transfers.
4Reliability
If traditional initialization methods are used, then the interface can be initialized, but response time for control transactions increases
Solution Approach 1:
By merging control and data transmission into a single interface, the patent enables direct and rapid control transactions between the host controller and peripheral device. The control commands are transmitted over the same high-speed data lanes, eliminating the need for separate control interface communication and reducing overall response time.
Data Source
AI summary
An example includes detecting receiving a bus turn-around (BTA) sequence after detecting a voltage level; sending a BTA acknowledgement in response to the BTA sequence; and sending a configuration command to a peripheral device after the interface is initialized based on the BTA acknowledgement.