Primary Secondary VCM Driver Synchronization
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Solution Overview
Problem
Camera control systems face challenges in extending voice coil motor (VCM) driver outputs beyond the capabilities of a single device while maintaining tight synchronization and minimizing latency, particularly in achieving duplication of VCM driver outputs between primary and secondary devices operating in open-loop and closed-loop modes.
Innovation Solution
A system utilizing a primary/secondary device configuration with a UART and Event Timer-based method to synchronize VCM code transmission and application, where the primary device processes and transmits VCM codes, and the secondary device mirrors the outputs, ensuring non-blocking communication and minimal processing impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a single device is used to control camera VCM outputs, then device complexity is minimized, but the number of available VCM driver outputs is limited
Solution Approach 1:
The system divides the VCM driver output functionality into multiple independent devices (primary and secondary), where each device can independently generate and transmit VCM codes. This segmentation allows the system to achieve more total outputs without requiring a single complex device to handle all outputs internally
Solution Approach 2:
The secondary device acts as a synchronized copy of the primary device's output functionality. By replicating the VCM driver capabilities in a secondary device and synchronizing its outputs with the primary device, the system effectively doubles the available output channels without requiring each device to independently process all camera control functions
2Quantity of substance
If multiple devices are used to extend VCM outputs, then the number of outputs is increased, but synchronization between devices becomes more difficult
Solution Approach 1:
The system employs a feedback mechanism where the secondary device receives VCM codes from the primary device via UART communication and automatically synchronizes its output timing to match the primary device. This feedback loop ensures that both devices remain synchronized without requiring complex external coordination
Solution Approach 2:
The patent replaces complex mechanical or hardware-based synchronization mechanisms with software-based timing control using event timers and UART communication protocols. This substitution allows for flexible, programmable synchronization that can be adjusted through software rather than requiring complex hardware interconnections
3Reliability
If tight synchronization is implemented between primary and secondary devices, then output skew is minimized, but processing latency increases
Solution Approach 1:
The system performs preliminary actions by pre-calculating and buffering VCM codes in advance before they are needed for output. The event timers are configured to trigger code transmission and application at precisely predetermined intervals, allowing the system to maintain tight synchronization without adding processing latency during critical output periods
Solution Approach 2:
The system maintains continuous operation of the VCM code generation, transmission, and application processes without interruption. By using periodic event timers that continuously generate and transmit codes at fixed intervals, the system ensures uninterrupted synchronized output while minimizing idle processing time that would increase latency
4Manufacturing precision
If event timer-based synchronization is used, then output skew is reduced below 20 μs, but device complexity increases
Solution Approach 1:
Each device is equipped with its own event timer that independently generates synchronization signals and controls the timing of VCM code application. This self-service approach allows each device to autonomously maintain precise timing without requiring complex external synchronization hardware or inter-device communication protocols
Solution Approach 2:
The UART communication interface serves as an intermediary that carries both VCM codes and timing synchronization information between the primary and secondary devices. This single communication channel handles multiple functions (data transmission and timing coordination) without requiring separate complex synchronization hardware
Data Source
AI summary
A system includes primary and secondary devices (e.g., camera controllers that drive voice coil motors) each having respective outputs and a communication link. The primary device includes first and second hardware timers, each of which expires at a time derived from a periodic control loop trigger. At first timer expiration, the primary transmits first updated values to the secondary. At second timer expiration, primary device hardware picks up and applies second updated values to the primary device outputs. In response to receiving the first updated values from the primary device, the secondary device applies the received first updated values to its outputs. The primary/secondary device combination provide a sufficient number of total outputs that they could not individually provide and further synchronize the outputs with small skew through the timers, which are programmable to also accommodate processing of inputs (e.g., from voice coil motor sensors) to compute the outputs.