SPI Slave Select Line for Interrupt Signaling
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Solution Overview
Problem
Existing SPI communication methods require additional lines and input/output processing for slave devices to signal interrupt requests to master devices, leading to increased complexity and delays in communication.
Innovation Solution
Implementing a method where slave devices signal interrupt requests by changing the state of the slave select line from an inactive to an active state, allowing for interrupt detection and data transfer without additional lines, using an input/output stage that manages the slave select line state based on both master and slave device control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an additional line is provided between slave and master for interrupt requests, then interrupt signaling capability is improved, but device complexity and input/output processing requirements increase
Solution Approach 1:
The slave select line is designed to serve dual purposes: it functions as the standard slave selection signal during normal SPI communication, and simultaneously serves as an interrupt request line when asserted by the slave device. This multi-functionality eliminates the need for a separate interrupt line, reducing device complexity while maintaining interrupt signaling capability.
Solution Approach 2:
The patent merges the slave select line and interrupt request line into a single shared signal path. The slave device asserts the slave select line to indicate both its selection status and its interrupt request status, combining two previously separate functions into one unified mechanism.
2Ease of operation
If the master polls slave devices to determine if they have data to send, then communication control is simplified, but communication delays increase
Solution Approach 1:
The slave device is enabled to proactively assert the slave select line as an interrupt request before the master would normally poll it. This preliminary action allows the slave to signal its readiness in advance, eliminating the waiting period inherent in polling-based communication and reducing overall communication delays.
Solution Approach 2:
The system implements feedback by allowing the slave device to actively signal its interrupt status through the slave select line. This feedback mechanism enables the master to respond immediately to slave requests rather than relying on periodic polling, improving communication efficiency while maintaining control.
Data Source
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AI summary
A Serial Peripheral Interface (20) connects a master device (10) and at least one slave device (1-3). The Serial Peripheral Interface (20) comprises a slave select line (25). The slave device (1) can signal an interrupt request to the master device (10) by changing a state of the slave select line (25) from a first state indicative of an inactive state to a second state indicative of an active state. The slave select line (25) can be connected to an input/output stage (52) of the slave device (1) which: allows the slave select line (25) to remain in the first state if the master device (10) or the slave device (1) does not change the state of the slave select line (25); and allows the slave select line (25) to change to the second state if the master device (10) or the slave device (1) wants to change the state of the slave select line (25).