Interrupt Scheme for Automated Pharmaceutical Dispensing
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Solution Overview
Problem
Conventional automated pharmaceutical dispensing systems using multiple bins connected via a parallel communication bus face inefficiencies due to time-consuming round-robin polling methods, which can lead to delays in reporting critical issues like jammed tablets, especially in systems with a large number of bins.
Innovation Solution
Implementing an interrupt scheme with a primary and secondary interrupt line, where each slave node has a unique delay time for asserting the secondary interrupt request, allowing immediate communication with the master node without centralized arbitration, thus eliminating the need for round-robin polling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If round-robin polling is used to check cell status, then all cells can be systematically monitored, but communication time increases significantly and critical events are delayed
Solution Approach 1:
Instead of the master controller polling each slave node sequentially (top-down approach), the invention inverts the communication paradigm by allowing slave nodes to autonomously interrupt the master node when events occur. This bottom-up approach eliminates the time waste of polling inactive nodes while ensuring critical events are reported immediately.
Solution Approach 2:
Slave nodes are empowered to self-initiate communication with the master node when events occur, rather than waiting to be polled. Each slave node autonomously determines when to report status information, eliminating the need for the master to systematically query every node and reducing communication latency for time-critical events.
2Productivity
If the number of cells is increased to expand system capacity, then more pharmaceuticals can be dispensed, but the time required for round-robin polling increases proportionally
Solution Approach 1:
The invention inverts the traditional master-slave communication model by allowing slave nodes to initiate interruptions to the master node. This eliminates the linear relationship between the number of slave nodes and polling time, as the master node no longer needs to sequentially query each slave node. System capacity can be expanded without proportionally increasing communication overhead.
3Speed
If interrupt requests are allowed from multiple slave nodes simultaneously, then event reporting speed increases, but bus contention and conflicts occur
Solution Approach 1:
The interrupt request mechanism is segmented into two distinct phases: event indication (slave node asserts interrupt) and data transmission (master node queries and slave node responds). This segmentation separates the speed-critical event reporting from the data exchange, allowing rapid interrupt assertion while managing bus usage efficiently through structured master-node interactions.
Data Source
AI summary
In a method for communication between a master node and a plurality of slave nodes connected by a bus therebetween, a first interrupt request is asserted by one of the plurality of slave nodes via a primary interrupt line. The plurality of slave nodes are electrically connected by the primary interrupt line. A unique delay time for requesting an interrupt is associated with each of the plurality of slave nodes. A second interrupt request is asserted by the one of the plurality of slave nodes via a secondary interrupt line electrically connecting the plurality of slave nodes. The second interrupt request is asserted in response to successfully asserting the first interrupt request and after the unique delay time associated with the one of the plurality of slave nodes. A message is then transmitted from the one of the plurality of slave nodes to the master node via the bus. Related systems and devices are also discussed, including the use of the primary and secondary interrupt request lines to provide bus arbitration between the plurality of slave nodes for communication with the master node.