Receiver particularly for a meter-bus

• US 20070239318A1
• Filed: 04/05/2006
• Published: 10/11/2007
• Est. Priority Date: 04/05/2006
• Status: Active Grant

• Current Assignee: Networked Energy Services Corporation (Cedrus Enterprises Holding SAL)
• Original Assignee: Echelon Corporation (Renesas Electronics Corporation)
• Inventors: vanRuymbeke, Gilles, Robinson, Andrew
• Granted Patent: US 7,973,561 B2
• Time in Patent Office: Days
• US Class Current: 700/295
• CPC Class Codes: G01F 15/063 using electrical means

Abstract

A receiver particularly suited for an M-BUS is described. During transmission, the receiver is disabled. After each transmission, nodes and states in the receiver are set to prepare the receiver to receive a signal. Once data is sensed, a feedback loop clips the input signal to the receiver to limit the swing of the input signal. The line of the power supply at the lower potential is modulated, rather than modulating the line at the higher potential, for the transmission of data.

Claims

1. A receiver for sensing current charges on a bus representing data on the bus comprising:

a capacitive signal path, coupled to the bus; and

a feedback loop for limited voltage swings in the capacitive signal path once a data signal is detected.

2. A receiver for sensing current changes on a bus where data is transmitted on the bus by modulating a voltage on the bus, comprising:

first means coupled to the bus for converting the current changes on the bus to an input signal;

capacitor means coupled to the first means; and

a gating circuit means activated by transmissions on the bus, for disabling the receiver during transmissions by grounding the capacitor means and for reestablishing bias points in the receiver following a transmission.

3. The method defined by claim 2, wherein the receiver further includes amplification means for amplifying the input signal, coupled to the capacitor means, a bistable circuit, coupled to an output of the amplification means.

4. The method defined by claim 3, wherein the capacitor means comprises a pair of capacitors coupled in series between the first means and amplification means, and wherein the gating circuit means couples a node between the capacitors to ground during the transmissions to disable the receiver.

5. The receiver defined by claim 4, wherein the gating circuit means includes means for establishing a predetermined polarity at the bistable circuit after a transmission.

6. The method defined by claim 5, wherein the gating circuit means includes means for establishing a predetermined bias on the capacitor means following a transmission.

7. A receiver for sensing current changes on a bus, where data is transmitted on the bus by modulating a power supply potential, comprising:

a gating circuit for disabling the receiver during transmissions;

an amplifier coupled to receive a potential representative of the current changes on the bus through a capacitor; and

the gating circuit being coupled to the capacitor such that the capacitor is coupled to ground during transmissions, and following the transmissions is coupled to a predetermined bias point after each transmission.

8. The receiver defined by claim 7, wherein the amplifier is coupled to a bistable circuit and where the comparator is set to a predetermined state following each of the transmissions.

9. A receiver for sensing current changes on a bus where data is transmitted on the bus by modulating a power supply voltage, comprising:

a sensing circuit coupled to the bus for converting the current changes on the bus to an input signal;

a first and second capacitor coupled in series, one of the capacitors being coupled to the sensing circuit to receive the input signal;

an amplifier, having a first input coupled to the other of the capacitors, the amplifier having a second input coupled to a biasing potential; and

a gating circuit coupled to sense transmissions on the bus, the gating circuit being coupled to a node between the capacitors for grounding the node during transmissions of data, and for coupling the first input of the amplifier to the biasing potential after the transmission of data.

10. The receiver defined by claim 9, including a bistable circuit having one input coupled to an output of the amplifier and the other input coupled to the biasing potential.

11. The receiver defined by claim 10, wherein the gating circuit is coupled to the bistable circuit to place it in a predetermined state after the transmission of data.

12. The receiver defined by claim 11, wherein the bistable circuit comprises an operational amplifier with a positive feedback path.

13. A method for operating a receiver which senses current changes on a bus, where data is transmitted on the bus by modulating a power supply potential on the bus, comprising:

sensing the current changes on the bus;

converting the current changes to an input signal;

capacitively coupling the input signal to an amplifier; and

determining when data is being transmitted and in response to the transmission, coupling the capacitor to ground so as to disable the receiver.

14. A method for operating a receiver which senses current on a bus, comprising:

sensing the current changes on the bus;

converting the current changes to an input signal;

capacitively coupling the input signal to an amplifier;

setting a bistable circuit in a predetermined state when data is sensed; and

limiting the voltage excursions on the capacitive coupling in response to a change of state in the bistable circuit.

15. A method for operating a meter-bus comprising:

maintaining one line of the meter-bus at a first potential; and

maintaining the second line of the meter-bus at a nominal potential less than the first potential, and then causing the second line to change to approximately a ground potential to represent the transmission of data on the bus.

16. A method for operating a meter-bus comprising:

maintaining a first higher potential line at a constant voltage; and

modulating a second lower potential line to transmit data.

17. The method defined by claim 16, wherein the second line is modulated between approximately zero volts and a potential less than the higher potential of the first line.