Communication with lighting units over a power bus
First Claim
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1. A method of communication among a plurality of entities connected to a power bus powered by a power supply having a power supply voltage, the method comprising:
- switching a connection between the power bus and the power supply from a low-impedance state to a high-impedance state by inserting a source load between the power bus and the power supply;
modifying a voltage on the power bus such that the modified voltage is less than the power supply voltage but greater than zero in accordance with the impedance ratio of the source load and a messaging load, at a first entity connected to the power bus, in accordance with an outgoing communication, by inserting the messaging load between the power bus and ground such that the source load and messaging load divide the power supply voltage on the power bus; and
detecting the modified voltage at a second entity connected to the power bus, thereby receiving the communication at the second entity.
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Abstract
A first entity communicates with a second entity over a shared power bus by switching the bus to a high-impedance state and modifying the voltage on the power bus, in accordance with an outgoing communication, such that the modified voltage is detected by the second entity and the communication is received thereto.
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Citations
19 Claims
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1. A method of communication among a plurality of entities connected to a power bus powered by a power supply having a power supply voltage, the method comprising:
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switching a connection between the power bus and the power supply from a low-impedance state to a high-impedance state by inserting a source load between the power bus and the power supply; modifying a voltage on the power bus such that the modified voltage is less than the power supply voltage but greater than zero in accordance with the impedance ratio of the source load and a messaging load, at a first entity connected to the power bus, in accordance with an outgoing communication, by inserting the messaging load between the power bus and ground such that the source load and messaging load divide the power supply voltage on the power bus; and detecting the modified voltage at a second entity connected to the power bus, thereby receiving the communication at the second entity. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 16, 18)
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13. A system for communicating among a plurality of entities powered by a power supply having a power supply voltage via a power bus, the system comprising:
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an impedance-switching circuit electrically connected between the power supply and the power bus for selecting between a power-supply output impedance and a source load, the source load having an impedance higher than the power-supply output impedance; a central controller for selecting, using the impedance-switching circuit, the source load to thereby place the power bus in a command mode and, thereafter, sending a command over the power bus by inserting a messaging load between the power bus and ground to thereby modify a voltage on the power bus to be less than the power supply voltage but greater than zero in accordance with the impedance ratio of the source load and a messaging load such that the source load and messaging load divide the power supply voltage on the power bus; and a light source for receiving the command, over the power bus, from the central controller and sending a response over the power bus thereto. - View Dependent Claims (14, 15, 17, 19)
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Specification