Single wire bus communication system with method for handling simultaneous responses from multiple clients

Abstract

A single wire bus communication system comprises a bus wire, a host device, and at least one client device, with each host and client device having pull-up and pull-down transistors to pull the bus wire 'high' or 'low', respectively. The system is arranged such that, in response to a “trigger event” that requires responses from multiple client devices simultaneously, the host device enables its pull-down transistor, and each client device disables its pull-down transistor when conveying a “low” logic level onto the bus. To avoid bus contention, each client's pull-up transistor is arranged to conduct more current when enabled than the host's pull-down transistor. Then, one or more of the client devices' strong pull-ups will overcome the single weak pull-down on the bus, thereby enabling numerous client devices to respond to a command that requires a response from multiple clients.