Abstract: A circuit for stealing power from an external system without interfering with a communication protocol may include wiring connectors configured to receive wires from the external system; a first voltage regulator to regulate a voltage on the plurality of wiring connectors at a plurality of voltage levels to encode a first multi-bit binary message according to the communication protocol to be sent to the external system; a current monitor to measure a plurality of current levels received through the plurality of wiring connectors and decode the plurality of current levels to determine a second multi-bit binary message sent from the external system according to the communication protocol; and a power converter that adjusts an amount of power stolen from the plurality of wiring connectors based at least in part on the voltage on the plurality of wiring connectors.

Abstract: A smart-home device may include an energy-storage element that stores energy harvested from an environmental system; a power wire connector and a return wire connector; and switching elements configured to operate in a first state where the switching elements create a connection between the power and the return; and a second state where the switching elements interrupt the connection between the power and return. The smart-home device may also include a circuit that controls the switching elements, where the circuit is configured to detect a zero-crossing of a current received through the power wire connector; wait for a first time interval after the zero-crossing is detected; after an expiration of the first time interval, enable active power stealing for a second time interval; and after an expiration of the second time interval, disable active power stealing.

Abstract: A doorbell chime bypass circuit includes a first node, a second node, and a bi-directional FET switch in series with the first node and the second current node. The bi-directional FET switch includes a first FET and a second FET in series, and is configured to cease conducting current between the first and second nodes when gate voltages of the first and second FETs are below a cut-off threshold. The bypass circuit further includes a sensing circuit configured to determine a level of current flowing through the bi-directional FET switch, and a switch controller configured to set the gate voltages of the first and second FETs to a level below the cut-off threshold when the sensing circuit senses that the level of current meets a doorbell press current threshold, causing the bi-directional FET switch to cease conducting current between the first and second nodes.

Abstract: A method of powering a controller using an intermediate device with power from an environmental system may include receiving current from a power wire from the environmental system; passing the current from the power wire to a second command wire from the controller; monitoring the current flowing between the power wire and the second command wire while the current is below a threshold indicative of an amount of current used to power the controller from the environmental system; detecting when the current flowing between the power wire and the second command wire exceeds the threshold indicating that the controller is sending a command to the environmental system to perform the function; and sending a command to environmental system using a first command wire from the environmental system after detecting that the current exceeds the threshold.

Abstract: A smart-home device may include a plurality of wire connectors configured to receive a plurality of signals from an environmental system; a plurality of diodes configured to receive the plurality of signals from the plurality of wire connectors, wherein at least two of the plurality of diodes have different voltage drops; and a power-stealing circuit that is configured to receive outputs of the plurality of diodes and to steal power through one of the plurality of wire connectors that is determined at least in part by the different voltage drops.

Abstract: A method of powering a controller using an intermediate device with power from an environmental system may include receiving current from a power wire from the environmental system; passing the current from the power wire to a second command wire from the controller; monitoring the current flowing between the power wire and the second command wire while the current is below a threshold indicative of an amount of current used to power the controller from the environmental system; detecting when the current flowing between the power wire and the second command wire exceeds the threshold indicating that the controller is sending a command to the environmental system to perform the function; and sending a command to environmental system using a first command wire from the environmental system after detecting that the current exceeds the threshold.

Abstract: A doorbell chime bypass circuit includes a first node, a second node, and a bi-directional FET switch in series with the first node and the second current node. The bi-directional FET switch includes a first FET and a second FET in series, and is configured to cease conducting current between the first and second nodes when gate voltages of the first and second FETs are below a cut-off threshold. The bypass circuit further includes a sensing circuit configured to determine a level of current flowing through the bi-directional FET switch, and a switch controller configured to set the gate voltages of the first and second FETs to a level below the cut-off threshold when the sensing circuit senses that the level of current meets a doorbell press current threshold, causing the bi-directional FET switch to cease conducting current between the first and second nodes.

Abstract: A method of powering a controller using an intermediate device with power from an environmental system may include receiving current from a power wire from the environmental system; passing the current from the power wire to a second command wire from the controller; monitoring the current flowing between the power wire and the second command wire while the current is below a threshold indicative of an amount of current used to power the controller from the environmental system; detecting when the current flowing between the power wire and the second command wire exceeds the threshold indicating that the controller is sending a command to the environmental system to perform the function; and sending a command to environmental system using a first command wire from the environmental system after detecting that the current exceeds the threshold.

Abstract: A device may include a rectifier circuit providing a rectified DC signal, a rechargeable energy-storage element, and a power-management integrated circuit (PMIC). The PMIC may include a charging circuit for the rechargeable energy-storage element; a current-sensing circuit that measures a current provided by the rectified DC signal; a programmable current limit; a voltage-sensing circuit that measures a voltage on the rechargeable energy-storage element; and a controller that regulates the current provided to a DC output of the PMIC. the DC output of the PMIC may be regulated based at least in part on the current provided by the rectified DC signal; the programmable current limit; and the voltage on the rechargeable energy-storage element. The DC output of the PMIC may provide energy to a plurality of other energy-consuming subsystems on the device and to the charging circuit for the rechargeable energy-storage element.

Abstract: A smart-home device may include a main power rail that provides power to components of the smart-home device; an integrator coupled to the main power rail that stores energy on an energy-storage device, where the energy stored on the energy-storage device is representative of an amount an amount of power provided to the smart-home device through the main power rail during an integration cycle of the integrator; and a counter that stores a number of integration cycles performed by the integrator during a time interval, where a total amount of power provided to the smart-home device through the main power rail during the time interval is represented by: (1) the number of integration cycles performed by the integrator during the time interval; and (2) the energy stored on the energy-storage device.

Abstract: A smart-home device may include a temperature sensor, energy-consuming subsystems, and processors programmed to receive a temperature measurement from the temperature sensor for an ambient environment surrounding the temperature sensor; receive inputs from the energy-consuming subsystems that indicate power-consuming activities of the energy-consuming subsystems; providing the inputs from the energy-consuming subsystems to a model that is trained to calculate an effect of the power-consuming activity of the energy-consuming subsystems on the temperature measurement from the temperature sensor; and calculating an estimate of the temperature of the ambient environment by compensating the temperature measurement from the temperature sensor with using the effect of the power-consuming activity of the energy-consuming subsystems.

Abstract: A smart-home device may include a plurality of wire connectors configured to receive a plurality of signals from an environmental system; a plurality of diodes configured to receive the plurality of signals from the plurality of wire connectors, wherein at least two of the plurality of diodes have different voltage drops; and a power-stealing circuit that is configured to receive outputs of the plurality of diodes and to steal power through one of the plurality of wire connectors that is determined at least in part by the different voltage drops.

Abstract: A smart-home device may include an energy-storage element that stores energy harvested from an environmental system; a power wire connector and a return wire connector; and switching elements configured to operate in a first state where the switching elements create a connection between the power and the return; and a second state where the switching elements interrupt the connection between the power and return. The smart-home device may also include a circuit that controls the switching elements, where the circuit is configured to detect a zero-crossing of a current received through the power wire connector; wait for a first time interval after the zero-crossing is detected; after an expiration of the first time interval, enable active power stealing for a second time interval; and after an expiration of the second time interval, disable active power stealing.

Abstract: A device may include a rectifier circuit providing a rectified DC signal, a rechargeable energy-storage element, and a power-management integrated circuit (PMIC). The PMIC may include a charging circuit for the rechargeable energy-storage element; a current-sensing circuit that measures a current provided by the rectified DC signal; a programmable current limit; a voltage-sensing circuit that measures a voltage on the rechargeable energy-storage element; and a controller that regulates the current provided to a DC output of the PMIC. the DC output of the PMIC may be regulated based at least in part on the current provided by the rectified DC signal; the programmable current limit; and the voltage on the rechargeable energy-storage element. The DC output of the PMIC may provide energy to a plurality of other energy-consuming subsystems on the device and to the charging circuit for the rechargeable energy-storage element.

Abstract: A circuit for stealing power from an external system without interfering with a communication protocol may include wiring connectors configured to receive wires from the external system; a first voltage regulator to regulate a voltage on the plurality of wiring connectors at a plurality of voltage levels to encode a first multi-bit binary message according to the communication protocol to be sent to the external system; a current monitor to measure a plurality of current levels received through the plurality of wiring connectors and decode the plurality of current levels to determine a second multi-bit binary message sent from the external system according to the communication protocol; and a power converter that adjusts an amount of power stolen from the plurality of wiring connectors based at least in part on the voltage on the plurality of wiring connectors.

Abstract: A circuit for stealing power from an external system without interfering with a communication protocol includes a plurality of wiring connectors configured to receive a plurality of wires, where the plurality of wiring connectors receive a plurality of current levels set by the external system according to the communication protocol; a first voltage regulator to regulate a voltage on the plurality of wiring connectors at a plurality of voltage levels according to the communication protocol; a current monitor to measure the plurality of current levels received through the plurality of wiring connectors; a second voltage regulator that provides a current-limiting output; and a power converter that optimizes an amount of power stolen from the plurality of wiring connectors based on the current-limiting output.

Abstract: A device may include a rectifier circuit providing a rectified DC signal, a rechargeable energy-storage element, and a power-management integrated circuit (PMIC). The PMIC may include a charging circuit for the rechargeable energy-storage element; a current-sensing circuit that measures a current provided by the rectified DC signal; a programmable current limit; a voltage-sensing circuit that measures a voltage on the rechargeable energy-storage element; and a controller that regulates the current provided to a DC output of the PMIC. the DC output of the PMIC may be regulated based at least in part on the current provided by the rectified DC signal; the programmable current limit; and the voltage on the rechargeable energy-storage element. The DC output of the PMIC may provide energy to a plurality of other energy-consuming subsystems on the device and to the charging circuit for the rechargeable energy-storage element.

Abstract: A smart-home device may include an energy-storage element that stores energy that is harvested from an environmental system and a solid state relay (SSR) switching integrated circuit (IC). The SSR switching IC may include switching elements that operate in a first state and a second state. The IC may also include a control circuit that causes the switching elements to operate in the first state to activate a function of the environmental system until the energy-storage element has dropped below a threshold. The control circuit may also cause the switching elements to operate in the second state and harvest energy from the environmental system, determine that a first time has elapsed since the switching elements began operating in the second state, and cause the one or more switching elements to again operate in the first state.

Abstract: A smart-home device may include a solid state relay (SSR) switching integrated circuit (IC). SSR switching IC may include switching elements configured to open and close a connection between a power wire and a return wire of an environmental system; a voltage sensor that measures a voltage across the one or more switching elements; a current sensor that measures a current through the one or more switching elements; and a temperature sensor that measures a temperature near the one or more switching elements. The smart-home device may also include a wireless communication device that periodically receives voltage, current, or temperature data originating from the SSR switching IC and transmits the voltage, current, or temperature data to a device management server. The device management server may receive batches of voltage, current, or temperature data from a plurality of smart-home devices.

Abstract: A circuit includes a monitoring circuit that monitors a voltage and a switching circuit. Closing the switching circuit causes an external AC load to receive power from an external AC source. The circuit further includes a control circuit that opens the switching circuit for a time interval, where the time interval begins after the voltage is below a lower threshold. The control circuit also ends the time interval after the voltage exceeds an upper threshold, where the time interval is short enough that the operation of the AC load is not affected during the time interval. The circuit also includes a power harvesting circuit that harvests power from the external AC source to raise the voltage during the time interval.