I2C Demultiplexer Using Rise Time Detection
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Solution Overview
Problem
As computer systems become more complex, the limited number of addresses in the I2C bus system becomes a bottleneck, as demultiplexers, which aid in distributing the I2C bus to multiple slave devices, require separate unique addresses, reducing the effective bandwidth when additional bits are used.
Innovation Solution
A demultiplexer is operated on an I2C bus without a unique address by using a rise time detection circuit to vary the coupling of input signal lines between sets of output signal lines based on the rise time of signals transmitted by the I2C master, allowing configuration without the need for separate addressing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If demultiplexers are added to distribute the I2C bus to multiple slave devices, then the system can support more slave devices, but the demultiplexers require separate unique addresses which reduces the effective bandwidth and increases address utilization
Solution Approach 1:
The patent extracts the address decoding function from the traditional I2C address bus and relocates it to the SDA data line through rise time detection. This removes the need for demultiplexer addressing, effectively taking out the address consumption bottleneck while maintaining the ability to support multiple slave devices.
Solution Approach 2:
The patent introduces rise time detection as an intermediary mechanism between the I2C master and slave devices. Instead of using traditional address decoding, the rise time of the SDA signal serves as the mediator to identify and select the target slave device, eliminating the need for separate demultiplexer addresses.
2Adaptability or versatility
If additional address bits are utilized to increase the number of addresses, then more devices can be addressed, but the effective bandwidth of the bus is reduced
Solution Approach 1:
The patent transitions from using address bits (temporal dimension) to using signal rise time characteristics (physical dimension) for device identification. This dimensional change allows the system to support multiple devices without consuming additional address space, thereby maintaining full bus bandwidth utilization.
Solution Approach 2:
The patent changes the parameter used for device identification from address bits to signal rise time. By modifying the rise time parameter of the SDA signal, the system can distinguish between different slave devices without requiring additional addresses, thus preserving bandwidth while increasing adaptability.
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
This approach enables efficient operation of demultiplexers on I2C buses in complex systems by dynamically reconfiguring signal line coupling based on signal rise times, thereby increasing bandwidth utilization without requiring additional addresses.
Implementation Method 1
The rise time detection circuit is also coupled to the input signal lines from the I2C master. In embodiments of the present invention, operating the demultiplexer includes determining, by the I2C master, whether to configure the demultiplexer to vary the coupling of input signal lines from a first set of output signal lines to a second set of output signal lines.
Data Source
AI summary
Operating a demultiplexer on an I2C bus, the demultiplexer including a set of input signal lines from an I2C master and a plurality of sets of output signal lines, the demultiplexer configured to couple the inputs among the output in dependence upon a demultiplexer select signal line that couples the demultiplexer to a rise time detection circuit, where the rise time detection circuit is also coupled to the input signal lines and the rise time detection circuit: monitors a voltage of at least one of the input signal lines, including: receiving, from the I2C master, a signal on one of the lines; and detecting rise time of the signal; and if the rise time of the signal is less than a predefined threshold, configuring the demultiplexer to vary the coupling of the input signal lines from a first set of outputs to a second set.