SDIO Client Event Register Mechanism for Host Interrupts
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Solution Overview
Problem
The SDIO protocol is host/master driven, preventing slave devices from initiating data transfers, which can lead to timeout errors due to latency issues with low-speed and low-power devices, particularly in IoT applications, and lacks mechanisms for efficient synchronization and power management.
Innovation Solution
The introduction of client and host event registers allows for direct communication between SD client and host devices, enabling the triggering of direct commands and maintaining synchronization, even in low-power modes, through a doorbell mechanism, thereby preventing timeouts and improving power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the SDIO protocol uses host/master driven architecture, then the host can control data flow, but slave devices cannot initiate data transfers leading to timeout errors
Solution Approach 1:
The patent introduces event registers as an intermediary mechanism between the slave device and host. The slave device can write to event registers to initiate data transfers without directly controlling the host, resolving the contradiction by providing initialization capability while maintaining host control architecture.
Solution Approach 2:
The slave device is enabled to self-initiate data transfers by writing to event registers, allowing it to service its own data transfer needs without requiring host polling or intervention, thus improving reliability while maintaining the host-driven architecture.
2Use of energy by moving object
If low-speed devices operate in low-power mode, then power consumption is reduced, but data transfer synchronization is lost causing timeouts
Solution Approach 1:
The event register mechanism allows preliminary action by the slave device to notify the host before data transfer. This enables the slave to wake the host from low-power mode and initiate transfers without continuous host polling, maintaining synchronization while reducing power consumption.
Solution Approach 2:
The event register system provides feedback from the slave device to the host, allowing the host to respond to slave-initiated transfer requests. This feedback mechanism maintains synchronization reliability while enabling low-power operation by eliminating continuous host monitoring.
3Reliability
If the host continuously monitors slave devices, then data transfer timing is maintained, but power consumption increases
Solution Approach 1:
The patent replaces continuous host monitoring with periodic action triggered by slave device events. The host only wakes to monitor data transfers when the slave device writes to event registers, maintaining timing reliability while dramatically reducing host power consumption during low-power periods.
Data Source
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AI summary
A method of improving synchronization over a secure digital (SD) bus between an SD host and an SD client device is described. The method includes writing to a client event register to interrupt the SD host for an SD extended command. The method also includes triggering the SD host to issue the SD extended command to the SD client device over the SD bus in response to the SD client device writing to the client event register.