PCI-CardBus Access Control Circuit
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Solution Overview
Problem
The existing PCI bus system faces challenges in connecting CardBus devices due to differences in signal specifications, leading to access conflicts and the need for costly PCI-CardBus bridges, which restrict the number of devices that can be connected and increase control complexity.
Innovation Solution
An access control device generates specific transaction start signals for both PCI and CardBus devices, allowing them to coexist on the same bus without a bridge, using a signal generator to differentiate addresses and manage transactions, thereby simplifying device configuration and reducing control load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a PCI-CardBus bridge is used to connect CardBus devices to the PCI bus, then compatibility and connection reliability are improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the bridge function from a separate physical component and integrates it into the PCI host control unit. The access control circuit within the host control unit now directly generates CardBus-specific signals (FRAME, C/BE#, IRDY#) based on PCI bus signals, eliminating the need for an external PCI-CardBus bridge while maintaining connection reliability
Solution Approach 2:
The patent merges the bridge functionality with the PCI host control unit by adding an access control circuit that can generate both PCI and CardBus signals. This consolidation combines multiple functions (PCI bus control, CardBus signal generation, address translation) into a single integrated controller, reducing device complexity and cost
2Adaptability or versatility
If a PCI-CardBus bridge is used to enable CardBus device connection, then connection capability is improved, but the number of connectable devices is reduced and control complexity increases
Solution Approach 1:
The PCI host control unit is enhanced with multi-functionality to directly support both PCI and CardBus devices. The access control circuit can generate appropriate signals (IDSEL for PCI, FRAME/C/BE# for CardBus) based on the target device type, making the host controller universal and eliminating the need for separate bridge hardware
Solution Approach 2:
The access control circuit automatically determines whether to access a PCI or CardBus device based on the address being accessed, and self-adjusts the signal generation accordingly. This self-service capability eliminates the need for external bridge control logic and reduces overall system control complexity
3Measurement precision
If the CPU continuously controls the bus change circuit to access different devices, then access control precision is improved, but control load and processing time increase
Solution Approach 1:
The access control circuit is pre-configured with the ability to generate both PCI and CardBus signals. During system initialization, the circuit is prepared to respond to access requests, and during operation, it automatically switches between signal types based on the target device address, eliminating the need for real-time CPU intervention in bus control
4Adaptability or versatility
If signal specifications of PCI and CardBus are made identical, then device compatibility is improved, but adaptability and standard flexibility are reduced
Solution Approach 1:
The access control circuit acts as an intermediary between the PCI bus and CardBus devices. It translates PCI bus signals into CardBus-specific signals (FRAME, C/BE#, IRDY#) while maintaining the original PCI signal specifications. This intermediary approach enables CardBus device compatibility without altering the PCI bus standard or requiring changes to existing PCI devices
Data Source
AI summary
An access control device controls access to a first device and a second device. The first device is connected with a first bus conforming to a first standard and conforms to the first standard. The second device is connected with the first bus and conforms to a second standard. The access control device includes a first signal generator and a second signal generator. The first signal generator generates a first transaction start signal indicating start of a transaction for the first device. The second signal generator generates a second transaction start signal for the second device based on the first transaction start signal.