Single Pin Address Allocation for I2C Slave Devices
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Solution Overview
Problem
Conventional I2C address designation methods using external pins are limited in allocating addresses to multiple slave devices, especially in environments with pin constraints, such as in multi-camera systems, where only two addresses can be allocated using a single pin and up to four addresses using two pins, restricting communication between multiple cameras and a single master device.
Innovation Solution
A slave device with a single address determination pin that can be connected to a power terminal, ground terminal, or through external resistors, utilizing internal and external resistors and switches to determine address states and allocate addresses based on voltage levels, allowing up to four unique addresses to be designated using a single external pin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional I2C address designation methods using external pins are used, then addresses can be allocated to slave devices, but the number of allocatable addresses is limited to two using a single pin and four using two pins, restricting communication between multiple cameras and a single master device
Solution Approach 1:
The patent changes the parameter of address determination from direct pin connection to voltage level detection. By measuring different voltage levels at a single pin (achieved through internal pull-up/pull-down resistors and external resistor configurations), the system can distinguish between multiple address states (0, 1, 2, 3) without requiring multiple pins, thus resolving the contradiction between address allocation capability and pin usage
Solution Approach 2:
The patent introduces voltage levels as an intermediary between the external pin and the address allocation logic. Instead of directly mapping pin connections to addresses, the system uses voltage levels (determined by resistor networks) as an intermediate representation that enables multiple address states to be encoded at a single pin, thereby increasing adaptability without proportionally increasing device complexity
2Adaptability or versatility
If the number of slave devices is increased beyond two or four, then more addresses are needed, but the number of external pins must be increased accordingly, which is not feasible in environments with limited pin availability
Solution Approach 1:
The patent makes a single external pin serve multiple functions by using it not just for address determination but also for potential data communication. The voltage level detection mechanism allows the same pin to encode multiple address values (0-3), effectively making one pin universal for both address selection and device identification purposes, thus supporting more slave devices without requiring additional pins
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
Enables efficient address allocation for up to four slave devices using a single external pin, facilitating smooth communication between multiple cameras and a master device, even in environments with limited pin availability.
Implementation Method 1
an address allocator configured to designate the address of the serial communications slave based on a plurality of state bits determined depending on a connection state of the single address determination pin
Implementation Method 2
connected to the power terminal through the first external resistor, or connected to the ground terminal through a second external resistor
Data Source
AI summary
A slave device includes: a serial communications slave having an address designated for performing serial communications with a master; a single address determination pin configured to be, selectively, connected to a power terminal without being connected to a first external resistor, connected to a ground terminal without being connected through a second external resistor, connected to the power terminal through the first external resistor, or connected to the ground terminal through a second external resistor; and an address allocator configured to designate the address of the serial communications slave based on a plurality of state bits determined depending on a connection state of the single address determination pin.