PAM-3 Bus Node Enumeration for Reliable Address Arbitration
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Solution Overview
Problem
Existing battery management systems face challenges in efficiently managing communication in larger battery cell packs due to increased requirements, particularly in systems using a daisy chain transformer protocol layer, where conflicts arise from multiple nodes attempting to communicate simultaneously using 3-state pulse amplitude modulation (PAM-3) without effective arbitration mechanisms.
Innovation Solution
Implementing a ternary modulation communication bus system with a node comprising a controller, receiver, and signal driver that applies ternary modulation states to the communication bus, utilizing an enumeration encoding scheme with specific rules to ensure balanced and alternating dominant and recessive states, enabling effective arbitration at the physical layer to resolve node identification and address assignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If multiple nodes use PAM-3 modulation simultaneously on a daisy chain bus, then communication speed is improved, but communication conflicts increase due to lack of arbitration
Solution Approach 1:
The patent implements preliminary arbitration before data transmission by having nodes send enumeration signals and receive acknowledgment signals. Nodes that fail to receive the enumeration signal within a predetermined time window are excluded from transmission, preventing conflicts before they occur. This preliminary action ensures only authorized nodes transmit, maintaining reliability while enabling high-speed PAM-3 communication.
2Device complexity
If nodes transmit without arbitration mechanism, then device complexity is reduced, but communication conflicts arise from simultaneous transmission
Solution Approach 1:
The patent segments the transmission process into distinct phases: enumeration phase (where nodes send their identification signals), acknowledgment phase (where the master confirms receipt), and data transmission phase. This segmentation allows simple nodes without complex arbitration logic to operate reliably, as the master controller manages the coordination between multiple nodes through structured time slots and signal sequences.
3Measurement precision
If enumeration process uses ternary modulation states, then address assignment precision is improved, but time consumption increases due to multiple timeslots
Solution Approach 1:
The patent uses periodic action by implementing enumeration in discrete timeslots where each node transmits its identification signal in a predetermined sequence. The master controller receives these periodic signals and assigns addresses based on the reception timing. This periodic structure enables precise address assignment through ternary modulation while managing time consumption through efficient timeslot allocation and predetermined transmission sequences.
Data Source
AI summary
A node for a ternary modulation communication bus system, the node comprising: a controller; a receiver configured to detect a ternary modulation state on the communication bus; and a signal driver configured to apply a ternary modulation state to a communication bus, wherein the ternary modulation state comprises one of: a first dominant state; a second dominant state; or a recessive state; wherein, during an enumeration process, the controller is configured to: receive an enumeration signal from the communication bus via the receiver; in response to the enumeration signal, control the signal driver to apply a sequence of ternary modulation states at a respective sequence of timeslots to the communication bus to represent a unique identifier of the node according to an enumeration encoding scheme, wherein the enumeration encoding scheme comprises one or more ternary encoding rules comprising: at each time slot the signal driver only applies the recessive state or a predetermined one of the first dominant state and the second dominant state specific to the time slot.