SPI Client Propagation Delay Compensation via Chip Select Timing
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Solution Overview
Problem
In SPI systems, propagation delays between the SPI host and client can cause data errors when the delayed data from the client is received at the host, as it may not align with the clock signal's edge, leading to lost data bits and reduced data throughput.
Innovation Solution
The SPI client transmits its first bit of data on the falling edge of the Chip Select (CS) signal, and subsequent bits on the appropriate edge of the clock signal, effectively advancing the data to align with the host's clock, thereby compensating for propagation delays and preventing data loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is transmitted through the SPI channel, then communication between host and client is enabled, but propagation delay causes data misalignment with clock edges
Solution Approach 1:
The system performs preliminary action by transmitting the first data bit in advance on the falling edge of the chip select signal before the clock signal arrives at the client. This anticipatory transmission compensates for the propagation delay, ensuring the data reaches the host in time to be sampled on the first rising clock edge without requiring additional delay elements or reducing clock frequency.
2Reliability
If propagation delay is compensated by reducing clock frequency, then data alignment is improved, but data throughput decreases
Solution Approach 1:
The patent applies preliminary action by advancing the first bit transmission to occur on the chip select falling edge before the clock signal arrives at the client. This allows the host to receive and sample all data bits at the original clock frequency without reduction, maintaining both data alignment reliability and high throughput productivity simultaneously.
3Reliability
If propagation delay is compensated by inserting delay elements, then data alignment is improved, but device complexity increases
Solution Approach 1:
The patent eliminates the need for delay elements or additional hardware by using the existing chip select signal timing. The first bit is transmitted on the chip select falling edge at the client, which naturally compensates for propagation delay without requiring any additional delay circuits, buffers, or complex synchronization hardware, thus maintaining low device complexity.
Data Source
AI summary
A method includes receiving a chip select signal at an SPI client device. The method also includes, responsive to receiving the chip select signal, transmitting a first bit of an SPI transmission to an SPI host device, where the first bit of the SPI transmission is transmitted with a delay based at least in part on a loop propagation delay of an SPI channel. The method includes receiving a clock signal at the SPI client device. The method also includes, responsive to receiving the clock signal, transmitting a second bit of the SPI transmission to the SPI host device.