Slave Device to Slave Device Communication on Shared Bus
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Solution Overview
Problem
Current I2C control data bus systems do not allow direct communication between slave devices, as slave-only devices cannot handle interrupts and thus cannot communicate with each other, limiting their ability to exchange data directly.
Innovation Solution
A master device with a bus interface circuit and processing circuit manages access to a shared control data bus, enabling slave device to slave device communication by granting or denying requests based on a word limit, monitoring the bus, and regaining control after communication ends.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If slave-only devices are used on the I2C control data bus, then device complexity is reduced and ease of manufacture is improved, but communication capability is limited as slave devices cannot communicate directly with each other
Solution Approach 1:
The master device serves as an intermediary between slave devices, receiving communication requests from one slave device and forwarding them to another slave device. This allows slave-only devices to communicate with each other without requiring interrupt handling capability, as the master device mediates all communications and manages the bus arbitration.
2Device complexity
If slave devices are restricted from handling interrupts, then device complexity is reduced, but direct communication between slave devices becomes impossible
Solution Approach 1:
The communication function is segmented between the master device and slave devices. The master device handles the complex interrupt arbitration and bus management functions, while slave devices are simplified to only handle data transmission. This segmentation allows slave devices to communicate with each other through the master without requiring interrupt capability at the slave level.
3Reliability
If the master device controls all bus access, then bus conflict prevention is improved, but communication efficiency decreases due to master device involvement in every transaction
Solution Approach 1:
The master device performs preliminary actions by pre-establishing communication permissions and arbitration rules before actual data transfer. Once permissions are granted, slave devices can exchange data more efficiently without requiring the master to be involved in every single byte transfer, thus maintaining reliability while improving efficiency.
Data Source
AI summary
In a shared bus where communications are managed by a master device, direct slave device to slave device (S2S) communications is implemented. A first slave device wanting to communicate with a second slave device may make a S2S communication request to the master device. The request may include a requested number of words that the first slave device wishes to send over the shared bus. The master device may have a current word limit which may vary based upon operating parameters. The master device may deny the request if the requested number of words is greater than the current word limit or if it does not support S2S communications. Denial of the request may also be for other reasons, like activity over the shared bus. If the master device grants the request, the slave device may send the requested number of words to another slave device over the shared bus.