Single-Wire Bus Access Using Slave-Initiated CMS and PWM Arbitration
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Solution Overview
Problem
Conventional single-wire bus systems require master-initiated communications, limiting efficiency and flexibility in mobile communication devices.
Innovation Solution
Implementing a single-wire bus system that allows slave circuits to initiate communications through current mode signaling, with a master circuit arbitrating access using pulse-width modulation (PWM) symbols to determine which slave circuit gains access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If master-initiated communications are used in conventional single-wire bus systems, then system simplicity is maintained, but communication efficiency and flexibility deteriorate
Solution Approach 1:
The patent inverts the conventional master-initiated communication model by enabling slave circuits to initiate communications. Slave circuits assert current mode signaling (CMS) to request bus access, and the master responds with PWM symbols to grant access. This inversion allows multiple slaves to contending for bus access independently, dramatically improving communication efficiency and flexibility without requiring complex additional hardware.
Solution Approach 2:
Slave circuits are empowered to self-initiate communications by asserting CMS when they need to communicate data to the master. This self-service capability eliminates the inefficiency of master polling and allows slaves to autonomously request bus access, improving overall system productivity while maintaining the simplicity of the single-wire bus architecture.
2Adaptability or versatility
If multiple slave circuits contend for bus access simultaneously, then communication flexibility improves, but access arbitration complexity increases
Solution Approach 1:
The patent uses parameter changes in the form of PWM symbol sequences to arbitrate bus access. The master circuit responds to CMS assertions by transmitting specific PWM symbols that encode access grant decisions. By varying PWM parameters (pulse width, frequency patterns), the system can flexibly arbitrate between multiple contending slaves without requiring complex additional arbitration hardware, maintaining simplicity while enabling versatile access control.
3Use of energy by moving object
If slave-initiated communications are implemented, then power consumption is reduced, but signaling complexity increases
Solution Approach 1:
The patent replaces complex continuous communication protocols with simplified event-driven signaling. Slave circuits use brief CMS assertions (current mode signaling) to initiate communications only when needed, rather than maintaining continuous communication states. The master responds with PWM symbols for arbitration and data transfer. This substitution of continuous signaling with discrete event-based signaling reduces power consumption while the PWM/PDM encoding schemes provide robust signaling without requiring complex additional mechanisms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances efficiency, reduces power consumption, and improves cost-effectiveness in mobile communication devices by enabling slave-initiated communications over a single-wire bus.
Implementation Method 1
a first voltage level is asserted on the single-wire bus for a first duration of time and a second voltage level is asserted on the single-wire bus for a second duration of time
Data Source
Figure 1A
Figure 1B~1C
Figure 2
AI summary
Slave-initiated communications over a single-wire bus are described in the present disclosure. In contrast to a conventional single-wire bus apparatus wherein communications over the single-wire bus are always initiated by a master circuit, a single-wire bus apparatus disclosed herein allows a slave circuit(s) to initiate communications over the single-wire bus. More specifically, multiple slave circuits can concurrently contend for access to the single-wire bus via current mode signaling (CMS). In response to the CMS asserted by the multiple slave circuits, a master circuit provides a number of pulse-width modulation (PWM) symbols over the single-wire bus to indicate which of the multiple slave circuits is granted access to the single-wire bus. By supporting slave-initiated communications over the single-wire bus, it is possible to improve efficiency, cost, and power consumption in an electronic device (e.g., smartphone) wherein the single-wire bus apparatus is deployed.