Dynamic Identifier Bus Arbitration for Serial Bus Latency
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Solution Overview
Problem
In mobile communication devices, high bus latency on shared serial buses limits the number of radio frequency devices that can be coupled, as higher priority devices dominate the bus, preventing lower priority devices from gaining access during concurrent arbitration processes, which is critical for time-critical applications.
Innovation Solution
A dynamic identifier with a unique and variable portion is used in bus arbitrations, where the variable portion is incremented after each unsuccessful access attempt and cleared after successful access, allowing lower priority devices to gain access by adjusting their priority based on a binary-weighted combination of both portions, and switching to a diversity bus when maximum consecutive arbitration failures are reached.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple devices are coupled to the serial bus, then the functionality and connectivity of the device are improved, but the bus latency increases and lower priority devices cannot gain access during concurrent arbitration
Solution Approach 1:
The patent implements dynamic priority adjustment by modifying the slave identifier during arbitration attempts. The variable identifier portion is incremented after each unsuccessful arbitration, dynamically changing the device's priority level to ensure eventual bus access without requiring fixed priority assignments.
Solution Approach 2:
The patent changes the parameter values of the slave identifier dynamically during arbitration. By incrementing the variable identifier portion and clearing it upon successful access, the system transforms static priority levels into dynamic parameters that adapt based on arbitration outcomes, ensuring fair access while maintaining high data rates.
2Speed
If high priority devices dominate the bus, then time-critical data transmission is improved, but lower priority devices are prevented from gaining access
Solution Approach 1:
The patent employs feedback mechanisms where arbitration outcomes are fed back into the slave identifier modification process. Successful arbitration triggers clearing of the variable identifier portion, while unsuccessful arbitration triggers incrementing, creating a feedback loop that ensures both high-priority transmission and eventual access for all devices.
Solution Approach 2:
The patent prepares the variable identifier portion in advance based on the number of consecutive arbitration failures, so that when a lower priority device finally gets a chance to access the bus, its identifier is already optimized for successful transmission, reducing wait time and ensuring fair access.
3Productivity
If bus clock frequency is increased, then data rate is improved, but power consumption and signal integrity issues increase
Solution Approach 1:
The patent achieves higher effective data rates by changing the prioritization parameter (slave identifier) rather than increasing the clock frequency. This parameter change allows more devices to access the bus efficiently without the power consumption and signal integrity penalties associated with higher clock speeds.
Data Source
AI summary
Systems, methods, and apparatus for improving bus latency are described. A method performed at a device coupled to a serial bus includes using a dynamic identifier in a first transaction conducted over a first serial bus. The dynamic identifier includes unique identifier and variable identifier portions. The device participates in a sequence of bus arbitrations until the slave device gains access to the first serial bus or a second serial bus. The value of the variable identifier portion may be increased after each bus arbitration that does not result in a grant of access to the first serial bus, and cleared after each bus arbitration that results in a grant of access to the first serial bus. A second transaction may be conducted over the first serial bus after gaining access to the first serial bus. The value of the dynamic identifier defines slave device priority for bus arbitrations.