Programmable Bus Device Address Configuration via Chip Select
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Solution Overview
Problem
In electronic systems with multiple identical slave devices on a bus, the need to assign unique addresses to each device is challenging due to default addresses being shared among devices of the same model or manufacturer, leading to conflicts and logistical issues with hard-programmed addresses.
Innovation Solution
Implementing a programmable address system where slave devices can set unique active addresses over the bus using a chip select signal and message protocol, allowing each device to be individually addressed without requiring additional external pins or registration with standards organizations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If default addresses are assigned to slave devices of the same model or manufacturer, then device identification and communication are simplified, but address conflicts occur when multiple identical devices are connected to the same bus
Solution Approach 1:
The slave device dynamically switches between default address mode and custom address mode based on the chip select signal state. When the chip select signal is inactive, the device responds to default addresses for easy identification. When the chip select signal is active, the device responds to custom addresses assigned by the master device, ensuring address uniqueness. This dynamic address switching resolves the contradiction between ease of operation and address uniqueness.
2Reliability
If hard-programmed addresses are used to ensure unique identification, then address conflicts are prevented, but device complexity and manufacturing cost increase
Solution Approach 1:
The device changes its address parameter dynamically based on operational mode. Instead of hard-programming unique addresses into each device, the system uses a configurable address parameter that can be set by the master device when needed. This parameter change approach maintains address uniqueness while avoiding the complexity of hard-programmed addresses and reducing manufacturing costs.
3Reliability
If additional external pins are added for address configuration, then unique addressing is enabled, but device pin count and system complexity increase
Solution Approach 1:
The chip select signal serves multiple functions: it acts as a standard chip select signal for device selection and simultaneously triggers custom address mode for unique addressing. This multi-functionality eliminates the need for separate address configuration pins, maintaining address uniqueness while reducing pin count and system complexity.
Solution Approach 2:
The chip select signal acts as an intermediary that mediates between the master device and slave device address configuration. By using the existing chip select signal as a trigger for custom address mode, the system avoids adding dedicated address configuration pins while still enabling unique addressing through the bus interface.
4Ease of manufacture
If addresses are assigned by system bus management entity, then address allocation is standardized, but flexibility in address assignment is reduced and registration requirements increase
Solution Approach 1:
The slave device is pre-configured with a default address that enables immediate communication and identification. This preliminary address configuration allows the device to be easily manufactured and integrated without requiring immediate registration or complex address assignment. When needed, the master device can later assign a custom address through the bus interface, providing flexibility while maintaining ease of manufacture.
Data Source
AI summary
An embodiment bus device with a programmable address includes a bus communication circuit connected to a bus terminal, a first pin terminal, a memory having a first register with a first address stored therein and a second register, and a state logic circuit. The state logic circuit detects a chip select signal on the first pin terminal, receives a first message through the bus communication circuit while the chip select signal is asserted, determines that the first message indicates an address set command, and saves an address value in the first message as a second address in the second register in response to a target address in the first message matching the first address. The state logic circuit further processes a second message received through the bus communication circuit in response to a target address of the second message matching the second address.