Time synchronization in connected emergency lighting

Abstract

According to certain embodiments, a luminaire may comprise: a node configured to keep absolute time and transmit the absolute time; a light engine comprising a plurality of lights; a driver configured to receive AC power from a power outlet, transform the power, thereby resulting in transformed power, and provide transformed power to the light engine; an emergency driver including a battery and a clock, wherein the emergency driver is configured to: detect whether the emergency driver receives the AC power; when the emergency driver receives the AC power, charge the battery and store the absolute time from the node; when the emergency driver does not receive AC power: provide battery power from the battery to the light engine; start the clock, wherein the clock provides an offset time from starting the clock; and determine a current absolute time based at least in part on the offset time stored in the clock and a most recently stored absolute time received from the node.

Description

[0001]2023PF80435 1 TIME SYNCHRONIZATION IN CONNECTED EMERGENCY LIGHTING FIELD The disclosure relates to emergency lighting. More particularly, the disclosurerelates to time synchronization in emergency lighting. DESCRIPTION OF THE RELATED ART Emergency lighting can be activated upon a power failure. This allows occupants in a building to safely exit the building. However, during a power failure, the emergency lighting may not have access to external devices to use to determine the time and date. Accordingly, it would be desirable for the emergency lighting to be able to maintain accurate time during a power failure. SUMMARY According to certain embodiments, a circuit comprises: a clock configured to keep an absolute time; memory configured to receive and stored the absolute time; and at least one controller configured to: detect whether the clock receives power; and responsive to detecting that the clock does not receive power: starting a timer, the timer providing an offset time from starting; and determining the absolute time based on the absolute time stored in the memory and the offset time provided by the timer. According to certain embodiments, a luminaire may comprise: a node configured to keep absolute time and transmit the absolute time; a light engine comprising a plurality of lights; a driver configured to receive AC power from a power outlet, transform the power, thereby resulting in transformed power, and provide transformed power to the light engine; an emergency driver including a battery and a clock, wherein the emergency driver is configured to: detect whether the emergency driver receives the AC power; when the emergency driver receives the AC power, charge the battery and store the absolute time from the node; when the emergency driver does not receive AC power: provide battery power from the battery to the light engine; start the clock, wherein the clock provides an offset time from starting the clock; and determine the absolute time based at least in part on the offset time stored in the clock and a most recently stored absolute time received from the node. 2023PF80435 2 According to certain embodiments, a method for keeping time in a luminaire, comprises: transmitting an absolute time by a node; detecting whether the luminaire receives the AC power; when the luminaire receives the AC power: charging the battery with DC power generated from the AC power; and storing the absolute time from the node in a memory; and when the luminaire does not receive AC power: providing battery power from the battery to a light engine; starting an offset timer, thereby causing the offset timer to provide an offset time from starting the offset timer; and determining the absolute time based at least in part on the offset time stored in the offset timer and the absolute time. BRIEF DESCRIPTION OF THE DRAWINGS The above and other aspects, features, and advantages of certain embodiments of the disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which: Fig.1 is a block diagram of a circuit in accordance with an embodiment of the disclosure; Fig.2 is a block diagram of a luminaire in accordance with an embodiment of the disclosure; Fig.3 is a block diagram of an emergency driver in accordance with an embodiment of the disclosure; Fig.4 is a screen for selecting testing time periods in accordance with an embodiment of the disclosure; Fig.5A is a screen for scheduling 30 second tests in accordance with an embodiment of the disclosure; Fig.5B is a screen for scheduling 90 minute tests in accordance with an embodiment of the disclosure; Fig.6A is a block diagram of a lighting system in accordance with an embodiment of the disclosure; Fig.6B is a block diagram of a standalone luminaire in accordance with an embodiment of the disclosure; Fig.7 is a block diagram of a node with battery backed power supply in accordance with an embodiment of the disclosure; Fig.8 is a flow diagram illustrating the normal operation and emergency modes in accordance with an embodiment of the disclosure; and 2023PF80435 3 Fig.9 is a flow diagram illustrating the normal operation and testing modes in accordance with an embodiment of the disclosure. DETAILED DESCRIPTION It should be appreciated that various embodiments of the present disclosure and the terms used therein are not intended to limit the technological features set forth herein to particular embodiments and include various changes, equivalents, or replacements for a corresponding embodiment. With regard to the description of the drawings, similar reference numerals may be used to refer to similar or related elements. It is to be understood that a singular form of a noun corresponding to an item may include at least one of the things, unless the relevant context clearly indicates otherwise. As used herein, each of such phrases as "A or B," "at least one of A and B," "at least one of A or B," "A, B, or C," "at least one of A, B, and C," and "at least one of A, B, or C," may include any one of, or all possible combinations of the items enumerated together in a corresponding one of the phrases. As used herein, such terms as "1st" and "2nd," or "first" and "second" may be used to simply distinguish a corresponding component from another, and does not limit the components in other aspect (e.g., importance or order). It is to be understood that if an element (e.g., a first element) is referred to, with or without the term "operatively" or "communicatively", as"coupled with," "coupled to," "connected with," or "connected to" another element (e.g., a secondelement), it means that the element may be coupled with the other element directly (e.g., wired connection), wirelessly, or via a third element. As used herein, the term "module" may include a unit implemented in hardware, software, or firmware, and may interchangeably be used with other terms, for example, "logic," "logic block," "part," or "circuitry". A module may be a single integral component, or a minimum unit or part thereof, adapted to perform at least one functions. For example, according to an embodiment, the module may be implemented in a form of an application-specific integrated circuit (ASIC). Battery backed up systems can include a battery backup for powering a load, in the event of a power failure. Additionally, during the power failure, the battery may power the load for a specified period of time, due to regulations or other criteria. Moreover, it may also be desirable to include regular testing of the battery backup according to a predetermined schedule. However, during a power failure, the clock may not receive power. For example, to increase the amount of time that the battery can provide power to the load, 2023PF80435 4 certain modules of the system, such as the clock, may not receive battery power during a power outage. Accordingly, during the power outage and when power is resumed, it may not be possible to use the clock to determine the date and / or time. Certain embodiments of this disclosure may allow determination of the date and / or time during a power outage and at power resumption. Referring now to Fig.1, there is illustrated a circuit 10. The circuit 10 can comprise an alternating current (AC) to direct current (DC) converter 15 and a battery 20 that are both configured to provide power to a load 22. The AC to DC converter 15 may be theprimary power provider to the load 22, and the battery 20 may be a backup power provider.For example, the AC to DC converter 15 may receive AC power from a power supply, such as a power outlet. The AC to DC converter 15 may transform the AC power to DC power, and provide the DC power to the load 22 and to charge the battery 20. It shall be understood that the circuit can include more than one AC to DC converter 15, and a reference to the AC to DC converter 15 may be considered a reference to all. During a power outage, the AC to DC converter 15 may not receive AC power. The battery 20 may be configured to provide power to the load 22 during a power outage. The circuit 10 can further include a clock 30, memory 20, at least one controller 25, and a timer 35. The clock 30 is configured to keep absolute time. The term “absolute time” shall be understood to mean a time that is based on an independent reference, such as time of day, date, year. The clock 30 might only receiver power from the primary power source, e.g., the AC to DC converter 15. For example, when the battery 20 is used as a backup, it may be desirable to only provide power to certain components to increase the amount of time that the battery can provide backup power to the load 22. Accordingly, the clock 30 can periodically provide the memory 20 with the absolute time. In certain embodiments, the clock 30 can provide the absolute time on a frequent enough basis that for all intents and purposes, the memory 20 can reliably store an accurate absolute time. The at least one controller 25 can detect whether the clock 30 receives power. Responsive to detecting that the clock 30 does not receive power, the at least one controller 25 can start the timer 35. The timer 35 can provide an offset time from starting, indicating an amount of time that has elapsed since the timer has started. Since clock 30 has periodically provided the memory 20 with the absolute time, the at least one controller 25 can determine the current absolute time based on the absolute time stored in the memory 20 and the offset 2023PF80435 5 time from the timer 35. For example, the at least one controller 25 can add the offset time from the timer 35 to the absolute time stored in the memory 20. In certain embodiments, the at least one controller 25 can detect whether the clock 30 receives power by detecting whether the AC to DC converter 15 receives AC power. If the AC to DC converter 15 does not receive power, such as during a power outage, the at least one controller 25 can determine that the clock 30 does not receive power. The at least one controller 25 may detect that the AC to DC converter 15 does not receive AC power in a variety of ways. For example, the AC to DC converter 15 can provide a low power DC output to the at least one controller 25. When the AC to DC converter 15 does not receive AC power, the DC output can be considered a logical 0. The logical 0 can trigger an interrupt to the at least one controller 25, indicating that the AC to DC converter does not receive AC power. Additionally, when the AC to DC converter 15 does not receive power, the at least one controller 25 can control the battery 20 to provide power to the load. Additionally, while the battery 20 provides power to the load, the at least one converter 25 can detect whether the AC to DC converter begins to receive AC power, such as after power resumption. When the at least one controller 25 detects that the AC to DC converter receives AC power, the at least one controller 25 may cause the battery 20 to discontinue providing power to the load 22. Additionally, the clock 30 may begin receiving power. Accordingly, the at least one controller 25 can synchronize the clock with the current absolute time. The at least one controller 25 can determine the current absolute time based on the offset time from the timer 35 and the absolute time stored in the memory 20. For example, the at least onecontroller 25 can add the offset time to the absolute time stored in the memory 20. The atleast one controller 25 can use the resultant time to synchronize the clock 30. In certain embodiments, the circuit 10 may also provide for battery backup testing. For example, the memory 20 may store a plurality of testing timers and a corresponding plurality of test periods. The testing timers can indicate, for example, regular monthly or weekly testing times, of different test periods. For example, the testing timers can indicate testing times at 2am on the 1stday of every month for test periods of 30 seconds. The testing timers can also indicate testing times each January 1stat 3am for a 90 minute test period. The testing timers can indicate remaining times until each test and countdown using a clocking signal. The at least one controller 25 detects when a particular one of the plurality of testing timers expires or reaches zero. For example, when a testing timer expires or reaches zero, the testing timer can cause an interrupt to the at least one controller 25. In certain 2023PF80435 6 embodiments, in response to detecting that one of the plurality of testing timers has expired or reached zero, the at least one controller 25 can cause the AC to DC converter 15 todiscontinue providing DC power to the load 22, and causes the battery 20 to provide power tothe load 22. In other embodiments, the at least one controller 25 may cause the battery to provide battery power to the load 22 in addition to the DC power from the AC to DC converter 15. The foregoing may cause the clock 30 to not receive power. Accordingly, in response to detecting that one of the plurality of testing timers has expired or reached zero, the at least one controller 25 can also start the timer 35. The at least one controller can detect when the timer 35 stores an offset time that is equivalent to one of the plurality of test periods that corresponds with the testing timer that expired or reached zero. Upon detection, the at least one controller 25 can cause the battery 20 to discontinue providing power to the load 22, and, where the AC to DC converter 15 discontinued providing power, causes the AC to DC converter 15 to resume providing DC power to the load 22. Additionally, upon detection, the at least one controller 25 can determine the current absolute time based on the offset time in the timer 35 and the absolute time stored in the memory 20, such as by adding the timer offset to the absolute time stored in the memory 20. Where the clock 30 has not received power during the text, the at least one controller 25 can use the resultant time to synchronize the clock 30. In certain embodiments, the memory 20 and the timer 35 can comprise a plurality of registers. The plurality of registers and the at least one controller 25 form portions of at least one processor. In certain embodiments, an AND gate can receive the output of the AC to DC converter 15 and a control signal provided by the at least one controller 25. An OR gate can receive the output of the AND gate and the output of the battery 20. The at least one controller 25 can cause the AC to DC converter 15 to discontinue or resume providing DC power to the load 22 by setting the control signal to a logical 0 or 1, respectively. The circuit 10 can include a variety of battery backed up systems. For example, the circuit 10 can include a luminaire. Luminaires can include a variety of devices that can provide lighting for a building. A luminaire can include both drivers and a light engine. Thus, the load 22 can include a light engine. The light engine can include the lighting elements such as bulbs, light emitting diodes (LEDs), or any other device that converts electricity to light, or any combination thereof. A driver can include an AC to DC converter 15 to convert AC power from a power outlet, and provide DC power to the light engine. 2023PF80435 7 Luminaires can also have safety features such as providing lighting during a power outage. For example, during emergencies, luminaires can automatically provide lighting guiding the occupants of a building to the exit. Accordingly, a luminaire can include a battery backup and an emergency driver to provide power to the light engine during an emergency, such as a power outage. An emergency driver can include a battery 20 to provide power to the light engine during a power outage. Building codes and regulations in a number of jurisdictions can dictate various requirements for providing battery backed up lighting. The requirements can include minimum amounts of times of battery backed up lighting during a power failure, as well as testing requirements. For example, the National Fire Protection Association (NFPA) publishes safety standards including the NFPA 101TM. The NFPA 101 is a safety code that outlines key requirements for emergency lighting. The requirements, among other things, calls for emergency lighting systems in stairs, aisles, corridors, and passageways leading to exits to provide 90 minutes of uninterrupted emergency illumination along a path of egress. Moreover, the requirements also set forth that the emergency lighting systems be tested monthly for 30 seconds, and annually for 90 minutes to maintain code compliance. During either testing for code compliance or an actual emergency, timekeeping can be difficult in standalone systems because standalone system may not have access to a gateway node connected to the internet. For example, a luminaire can include anode that includes the clock 30. However, the clock 30 might not be configured to receivepower from the battery 20 to maximize the amount of time that the battery 20 can power the light engine. Since the clock 30 does not receive power, the standalone system might not be able to receive the current time from an external source. Accordingly, the emergency driver can also include memory 20, at least one controller 25, and a timer 35. During normal operations, the emergency driver can store the absolute time from the node. In response to detecting that the clock does not receive power, such as during a power outage, the emergency driver can start a timer that measures an offset time from starting the timer. When power resumes, the emergency driver can synchronize the clock with a current absolute time, based on the absolute time that was last stored, and the offset time. Referring now to Fig.2, there is illustrated a luminaire 100 in accordance with an embodiment of the disclosure. The luminaire 100 comprises a light engine 110, a driver 120, an emergency driver 130, and a node 140. 2023PF80435 8 The light engine 110 can include the lighting elements such as bulbs, light emitting diodes (LEDs), any other device that converts electricity to light, or any combination thereof. The luminaire 100 can receive AC power from an AC power source 150. The AC power source can be, for example, a standard plug outlet, for example, National Electrical Manufacturers Association standard 120 V AC supply voltage at 60 Hz. Other standards can also be used. The driver 120 can provide DC power from conversion of the AC power to the light engine 110. The luminaire 100 can include an AC to DC converter that receives the AC power and converts the AC power to DC power. In certain embodiments, the driver 120 may include an AC to DC converter that provides DC power to the light engine 110 and the emergency driver 130 to charge the battery. In other embodiments, each of the driver 120 andemergency driver 130 may include an AC to DC converter. In another embodiment, theemergency driver 130 may include an AC to DC converter, where the light engine 110 routes the AC power to the emergency driver 130, receives the DC power, and provides the DC power to the light engine 110. Reference to an AC to DC converter shall deemed to refer to any AC to DC converter or all of AC to DC converters in the luminaire. The AC to DC converter can comprise, for example, a voltage rectifier. The node 140 can include a transceiver, such as a Bluetooth Low Energy (BLE) transceiver, or a Zigbee transceiver, and a clock that provides the absolute time for the luminaire. The node 140 can synchronize the block with an absolute time received from an external electronic device via a BLE transceiver, or from a master node via a Zigbeetransceiver. The node 140 can be configured to receive DC power from conversion of ACpower. However, the node 140 might not be configured to receive power from the battery during a power outage to increase the amount of time that the battery can provide power to the light engine 110. The emergency driver 130 can be configured to operate in one of three modes– (1) normal operation mode, (2) emergency mode, and (3) testing mode. In the normaloperation mode, the emergency driver 130 charges a battery with DC power from the AC to DC converter (as will be shown in Fig.3). The emergency mode refers to operation of the emergency driver 130 during a power outage. In the emergency mode, the emergency driver 130 controls the battery to provide power to the light engine 110. The testing mode refers to a scheduled testing of the battery backup, and can also include manual testing. In the testing mode, the emergency driver 130 can cause the driver 120 to discontinue providing DC 2023PF80435 9 power, and controls the battery to provide power to the light engine 110 for a predetermined amount of time. Alternative, the emergency driver 130 may control the battery to provide power to the light engine 110 in addition to driver 120 providing DC power. The foregoing may allow users to ascertain that testing is occurring by the brighter light from the light engine. During the normal operation mode, the emergency driver 130 can charge the battery, store the absolute time from the node 140, and detect whether the driver 120 receives AC power. During the normal operation mode, the emergency driver 130 can charge the battery with DC power from an AC to DC converter that is located either in the emergency driver 130 or in the driver 120. Additionally, the emergency driver 130 periodically receives and stores the absolute time from the node 140. In certain embodiments, the emergency driver 130 may include a register that receives the absolute time from the clock in the node 140. During normal operation, the emergency driver 130 can detect whether the driver 120 receives AC power from the power source 150. It shall be understood in this document that detection of a condition is not necessarily direct detection of the condition. For example, detection of a condition can include detection of a circumstance that logically implies the condition. For example, the emergency driver 130 can detect whether the driver 120 receives AC power by detecting whether an AC to DC converter receives AC power, because whether an AC to DC converter receives AC power implies whether the driver 120 receives DC power. In certain embodiments, an AC to DC converter may be configured toprovide a high digital logic signal indicating the reception of AC power, and a low digitallogic signal indicating the absence of AC power to at least one controller in the emergency driver 130. The low digital logic signal can interrupt the at least one controller or wakeup the at least one controller from a sleep mode. When the emergency driver 130 detects that the driver 120 does not receive AC power, the emergency driver 130 enters into an emergency mode. The emergency mode occurs, for example, during a power outage. The emergency driver 130 can start an offset timer, provide battery power from the battery to the light engine 110, and detect whether the driver 120 resumes receiving AC power. In certain embodiments, the offset timer can be a register. The emergency driver 130 can detect whether the driver 120 receives AC power by, for example, receiving the digital logic signal from the AC to DC converter. The 2023PF80435 10 digital logic signal indicating receipt of the AC power can trigger an interrupt with a controller. Detection of AC power received by the driver 120 indicates power resumption.Accordingly, responsive to detecting that the driver 120 receives AC power, the emergencydriver 130 can discontinue battery power to the light engine 110, and revert to charging the battery with the DC power. Additionally, the emergency driver 130 can determine a current absolute time based on the offset time from the timer and the stored absolute time. It is noted that during the emergency mode, the node 140 might not receive power. Accordingly, the stored absolute time by the emergency driver 130 can be the approximate time of the power outage. Accordingly, application of the offset time from the timer to the absolute time stored by the emergency driver 130 can result in the current absolute time. The emergency driver 130 can synchronize the clock in the node 140 with the foregoing current absolute time. In certain embodiments, the emergency driver 130 can also detect whether the offset time in the timer reaches a predetermined offset. For example, where regulations require ninety minutes of backup, when the timer reaches a ninety-minute offset, the emergency driver 130 can discontinue power to the light engine 110. By discontinuing the battery power to the light engine 110, the battery power is saved. It is noted that the predetermined offset can be set to a regulated minimum or an amount of time that would likely result in satisfactory egress of the all occupants. As result, in the event of an intermittent power resumption, followed by an additional power outage, the battery recharges faster and is more likely to provide sufficient backup power during the subsequent power outage. In certain embodiments, in the testing mode, the emergency driver 130 may cause the driver 120 to discontinue providing DC power to the light engine 110. Alternatively, the emergency driver 130 may permit the driver 120 to continue providing DC power to the light engine 110. For example, the emergency driver 130 may conduct a scheduled test. The emergency driver 130 may include a plurality of testing timers stored in registers. The testing timers are associated with a corresponding plurality of test periods. For example, the testing timers can indicate amounts of time until a scheduled tests. In certain embodiments, the luminaire 100 can receive a testing schedule from an external electronic device, such as a smartphone or tablet, via the node 140. The emergency driver 130 can convert the testing schedule into amounts of time until scheduled tests according to the schedule. The amounts of time can be stored in registers that countdown. When of the registers has expired (fully counted down, or reached zero), the register can trigger an interrupt with at least one controller in the emergency driver 130. 2023PF80435 11 In response to detecting that one of the plurality of timers has expired, the emergency driver 130 starts an offset timer, can discontinue DC power from the driver 120 to the light engine 110, and provides battery power to the light engine 110. Alternatively, the emergency driver 130 may permit the driver 120 to provide the DC power in addition to providing the battery power. When the offset time of the offset timer equals the time period for the scheduled test, the emergency driver 130 discontinues battery to the light engine 110 and, where the DC power has been discontinued, resumes DC power from the driver 120. Additionally, the emergency driver 130 can apply the offset time from the offset timer to the absolute time stored by the emergency driver 130, resulting in a current absolute time. Where the clock of the node 140 has received power during the test, the emergency driver 130 can synchronize the clock of the node 140 with the foregoing current absolute time. In certain embodiments, the emergency driver 130 can include at least one processor that include the at least one controller and the registers that store the absolute time, the timers, and the plurality of testing timers. In certain embodiments, the emergency driver 130 can control whether the battery or an AND gate can receive the output of the AC to DC converter 15 and a control signal provided by the at least one controller 25. An OR gate can receive the output of the AND gate and the output of the battery 20. The at least one controller 25 can cause the AC to DC converter 15 to permit, discontinue, or resume providing DC power to the load 22 by setting the control signal to a logical 0 or 1. Referring to Fig.3, there is illustrated a block diagram of an emergency driver 130. The emergency driver 130 can include an AC to DC converter 210, a battery charger 220, a battery 230, and output converter 240, and at least one processor 250. The at least oneprocessor 250 include at least one controller 250a and a plurality of registers 250b.The AC to DC converter 210 can be configured to receive AC power from a power outlet 150 and convert the AC power to DC power. The AC to DC converter 210 can provide DC power to the node 140 and the battery charger 220. The battery charger 220 can receive the DC power and charges the battery 230. The output converter 240 can receive the battery power from battery 230, and provide the battery power to the light engine 110. The at least one processor 250 can control the battery charger 220 and the output converter 240. In certain embodiments, the AC to DC converter 210 can generate a digital logic signal that is high when the AC to DC converter 210 receives AC power, and low when the AC to DC converter 210 does not receive AC power. The AC to DC converter 210 provides the digital logic signal to the at least one controller 250a. A change in the digital 2023PF80435 12 logic from the AC to DC converter 210 can trigger an interrupt in the at least one controller 250a, thereby causing the at least one controller 250a to detect whether the AC to DC converter receives AC power. During the normal operation mode, the one of the registers 250b can periodically receive the absolute time from the node 140. In certain embodiments, the at least one controller 250a can enter a low power mode during the normal operation mode. In certain embodiments, the node 140 receives power from the AC to DC converter, but is not configured to receive power from the battery 230. Accordingly, during a power outage, the node 140 might no longer maintain the absolute time. However, one of the registers 250b can store the most recently received absolute time from the node 140, which can be deemed the time of the power outage. To maintain the absolute time during a power outage, in certain embodiments, in response to receiving a high to low digital logic signal from the AC to DC converter 210, the at least one controller 250a can start an offset timer using one of the registers 250b. The emergency driver 130 can determine the current absolute time by applying the stored absolute time and the offset time from the registers 250b. Upon detecting a change from a low to high digital logic signal from the AC to DC converter 210, the at least one controller 250a can determine the current absolute time based on the absolute time and offset time from the registers 250b. The at least one controller 250a can apply the offset time to the absolute time, thereby determining the current absolute time. The at least one controller 250a can load the foregoing current absolute time into the node 140. The emergency driver 130 can also perform testing. In certain embodiments, the node 140 can receive testing schedule and provide the testing schedule to the emergency driver 130. The emergency driver 130 can generate a number of testing timers that indicate a time until testing. The testing timers can be written to some of the registers 250b and the registers 250b storing the testing timers can be configured to countdown. When one of registers 250b expires (reaches zero), the register can interrupt the at least one controller 250a. In response, in certain embodiments, the at least one controller 250a can cause the driver 120 to discontinue providing DC power to the light engine 110, cause the battery 230 to provide battery power to the light engine 110, and start the offset timer. In other embodiments, the at least one controller 250a can cause the battery 230 to provide battery power to the light engine 110 in addition to the DC power. When the offset timer reaches the testing period (such as 30 seconds, or 90 minutes according to the NFPA 101 standard), the at least one controller 250a can, where the driver has discontinued providing DC power, cause 2023PF80435 13 the driver 120 to resume providing DC power to the light engine 110, cause the battery 230 to discontinue providing battery power to the light engine 110, and use the stored absolute time and the offset time to determine the current absolute time. The at least one controller 250a can write the current absolute time to the node 140 where the clock in the node 140 did not receive power during the test. In certain embodiments, after the luminaire 100 is powered up, the node 140 and the emergency driver 130 can be powered and the battery 230 charged. In certain embodiments, the node 140 may form an ad hoc network with other nodes and synchronize to an absolute time provided by a master node. In other embodiments, when the node 140 is powered, the node 140 may be discoverable by a BLE application in an external electronic device, such as a smartphone or tablet. The external electronic device can synchronize the clock of the node 140 to the clock in the external electronic device. Moreover, the node 140 can receive a testing schedule from the external electronic device. Referring now to Figs.4, 5A and 5B, there is illustrated a block diagram of screen on an external electronic device that can provide a testing schedule to the emergency driver 130 via the node 140. Fig.4 is a block diagram of a screen for between 30 second tests 310 and 90 minutes tests 320. Selection of the 30 second tests 310 causes presentation of the display screen of Fig.5A, while selection of the 90 minutes tests 320 causes presentation of the display screen of Fig.5B. The user can select the date and time of the next test as well as the frequency of recurrence. Upon selecting the “Save” button, the external electronic device can transmit the schedule to the node 140. The emergency driver 130 can then store the testing schedule. Additionally, the luminaire 100 including an emergency driver 130 with an internal timer can be used in conjunction with other luminaires 100 that might not keep absolute time during either a power outage or testing. Referring now to Fig.6A, there is illustrated a light system including a plurality of luminaires 100. One of the luminaires 100’ includes an emergency driver 130 with an internal timer. Luminaire 100’ and remaining luminaires 100” can enter emergency and testing modes. When luminaire 100’ transitions from the emergency mode to normal operation mode, the emergency driver 130 determines current absolute time and synchronizes node 140. Node 140 then synchronizes the nodes of each of the remaining luminaires 100”. Referring now to Fig.6B, a standalone luminaire 500 is illustrated in accordance with an embodiment of the disclosure. The standalone luminaire 500 can include an emergency driver 130, a battery 230, and a connectivity node 510. The connectivity node 2023PF80435 14 510 can be configured to connect to a network, but might not be permanently or regularly connected to the network. When the connectivity node 510 establishes a connection to the network, it may receive the absolute time from the network. The connectivity node 510 may be AC powered. Additionally, the connectivity node 510 may include non-volatile memory and a real time clock that keeps track of the absolute time. The real time clock may periodically receive real time information from an external device, such as a smartphone. The connectivity node 510 may periodicallycopy the real time from the real time clock to the non-volatile memory. However, theconnectivity node 510 might not receive battery 230 power. Accordingly, when the AC power is interrupted, the connectivity node 510, including the real time clock, might power down and lose time synchronization. It is noted that a real time clock is used by way of example, and not limitation. For example, simple clocks can be used, with varying degrees of accuracy, depending on the regularity of synchronization. The emergency driver 130 may include a “heartbeat” clock. In certain embodiments, the accuracy of the heartbeat clock may not be as high as the accuracy of the real time clock, and may comprise a basic timer for cost reasons. In certain embodiments, the connectivity node 510 may regularly program the heartbeat clock of the emergency driver 130 with the real time clock during normal operation mode. In certain embodiments, the heartbeat clock cycle can be programmed by the emergency driver 130. In certain embodiments, the heartbeat clock may cover a relatively large time window such as four weeks. The heartbeat clock may count up or down with a certain time step size until the heartbeat cycle is covered. The time step-size may be, for example 15minutes, although other time step-sizes may be used. The connectivity node 510 may detectperiodic moments that the heartbeat cycle is completely restarted and may store the actual real time clock moment at cycle completion in non-volatile memory. It is noted that the foregoing is not limiting, and the future heartbeat cycle restart can be used. In certain embodiments, the connectivity node 510 may write the heartbeat cycle on a less frequent basis, such as once per the emergency driver 130 test schedule. Accordingly, when there is an interruption of AC power, the connectivity node 510 may not receive power. Accordingly, the connectivity node 510 may lose its actual clock information, except for the last stored real time clock reference remains available in the non- volatile memory. As a result, the emergency luminaire 500 may lose its time reference. However, the emergency driver 130 may remain powered via the battery. Accordingly, the 2023PF80435 15 emergency driver 130 may use the heartbeat clock to maintain operation of a heartbeat cycle to have a notion of the absolute time. When power is resumed, the real time clock of the connectivity node 510 may read the real-time clock reference from its non-volatile memory and the actual heartbeat cycle of the heartbeat clock of the emergency driver 130. With the foregoing information, the connectivity node 510 may determine an absolute time until the connectivity node 510 subsequently connects to the network. When the connectivity node 510 subsequently connects to the network, the real time clock synchronizes to the absolute time from the network. Referring now to Fig.7, there is illustrate a block diagram of a node 140 with a battery backed power supply in accordance with an embodiment of this disclosure. An OR- gate 610 receives an output from the battery 230 and the AC to DC converter 210. The node140 can be powered when AC to DC converter 210 does not receive AC power. The node140 can sense that the AC to DC converter 210 does not receive AC power and place itself in a low power mode to consume less battery, but still allows the clock to maintain time. Upon power resumption, the node 140 will have the accurate absolute time. Referring now to Fig.8, there is a flow diagram describing normal operation and emergency modes with an embodiment of this disclosure. At 705, the emergency driver 130 can receive an absolute time by the node 140. At 710, the emergency driver 130 can detect whether the luminaire receives the AC power. When the luminaire receives the AC power (710: YES), at the emergency driver can charge the battery with DC power generated from the AC power. At 720, the emergency driver 130 can store the absolute time from the node and repeat detecting whether the luminaire receives the AC power at 710. From 705, 710: YES, and 715-820 can be deemed the normal operation mode. When the luminaire does not receive AC power (710: NO), the emergency driver 130 can enter an emergency mode. At 725, the emergency driver 130 can provide battery power from the battery 230 to a light engine 110. At 730, the emergency driver 130can start an offset timer, thereby causing the offset timer to provide an offset time fromstarting the offset timer. At 735, the emergency driver 130 can determine the absolute time based at least in part on the offset time stored in the offset timer and the absolute time stored during the last iteration of 720. The emergency driver 130 can remain in the emergency mode until detecting AC power (740: YES). In response to detecting AC power at 740, the emergency driver 130 synchronizes the node 140 at 745 with the current absolute time based on the offset time of 2023PF80435 16 the timer and the absolute time stored during the last iteration of 720. The emergency driver 130 then returns to 715. Referring now to Fig.9, there is a flow diagram describing normal operation and testing modes with an embodiment of this disclosure. At 805, the emergency driver 130 stores a plurality of testing timers associated with a corresponding plurality of test periods. In certain embodiments, emergency driver 130 can receive a plurality of testing times from an external electronic device via the node 140. The emergency driver 130 can determine a plurality of values for the plurality of timers based on the plurality of testing times. At 810, the emergency driver 130 is in the normal operation mode, until detecting when one of the plurality of testing timers expires at 815. Responsive to detecting that one of the plurality of timers expires, theemergency driver 130 may cause the battery to provide battery power to the light engine 110 at 820. In certain embodiments, the emergency driver 130 may cause the driver 120 to discontinue providing DC power to the light engine 110. Alternatively, the emergency driver 130 may permit the driver 120 to continue providing DC power to the light engine 110 in addition to the battery. At 825, the emergency driver 130 may start the offset timer. For example, the emergency driver 130 may start the offset timer where the clock in the node 140 does not receive power during the test. The emergency driver 130 remains in the testing mode until at 830, the offset time of the offset timer is equivalent a timer periods that corresponding to the testing timers that expired during 815. In response, the emergency driver 130, where the driver 120 has discontinued providing power, causes the driver to resume providing power to the light engine, and discontinues the battery power at 835. At 840, the emergency driver 130 synchronizes the absolute time in the node 140 based on the absolute time stored by the emergency driver and offset time, where the clock in the node 140 did not receive power during the test. After 840, the emergency driver 130 can return to the normal operation mode 810. According to certain embodiment of the disclosure, a circuit 10 comprises: a clock 30 configured to keep an absolute time; memory 20 configured to receive and stored the absolute time; at least one controller 25 configured to: detect whether the clock 30 receives power; and responsive to detecting that the clock 30 does not receive power: starting a timer 35, the timer providing an offset time from starting; and determining a current absolute time based on the absolute time stored in the memory 20 and the offset time provided by the timer 35. 2023PF80435 17 According to certain embodiments, the circuit 10 further comprises a battery 20, and a load 22, and wherein the at least one controller 25 controls the battery 20 to power the load 22, responsive to detecting that the clock 30 does not receive power. According to certain embodiments, the circuit 10 further comprises an alternating current (AC) to direct current (DC) converter 15 configured to receive AC power from a power supply and provide DC power; and wherein detecting that the clock 30 does not receive power comprises detecting that the AC to DC converter 15 does not receive AC power. According to certain embodiments, the circuit 10 further comprises a battery 20 and a load 22, and wherein the at least one controller 25 is configured to: when the AC to DC converter 15 receives the AC power, charge the battery 20 with the DC power; when the AC to DC converter 15 does not receive the AC power: control the battery 20 to provide power to the load 22. According to certain embodiments, the load 22 comprises a light engine 110. According to certain embodiments, a luminaire 100 comprises: a node 140 configured to keep absolute time and transmit the absolute time; a light engine 110 comprising a plurality of lights; a driver 120 configured to receive AC power from a power outlet 150, transform the power, thereby resulting in transformed power, and provide transformed power to the light engine 110; and an emergency driver 130 including a battery 230 and an offset timer 250b, wherein the emergency driver is configured to: detect whether the driver 120 receives the AC power; when the driver 120 receives the AC power, charge the battery 230 and store the absolute time from the node 140; and when the driver 120 does not receive AC power: provide battery power from the battery 230 to the light engine 110; start the offset timer 250b, wherein the offset timer provides an offset time from starting the offset timer; and determine the absolute time based at least in part on the offset time stored in the offset timer 250b and the absolute time. According to certain embodiments, the node 140 further comprises a Bluetooth Low Energy (BLE) transceiver, and wherein the node 140 keeps the absolute time by synchronizing with an external electronic device. According to certain embodiments, the node 140 is configured to receive the absolute time from an external master node. According to certain embodiments, the node (140) comprises a connectivity node (510), the emergency driver (130) comprises a heartbeat timer. 2023PF80435 18 According to certain embodiments, store the absolute time from the node comprises programming the heartbeat timer with the connectivity node (510). According to certain embodiments, the emergency driver 130 further comprises: at least one controller 250a; memory 250b storing a plurality of testing timers associated with a corresponding plurality of test periods; wherein the at least one controller 250a is configured to: detect when one of the plurality of testing timers expires; and responsive to detecting that one of the plurality of timers expires: cause the battery to provide battery power to the light engine 110; start the offset timer 250b; when the offset time of the offset timer 250b is equivalent to a one of the corresponding plurality of timer periods that corresponds the one of the plurality of testing timers: cause the battery to discontinue providing battery power to the light engine 110. According to certain embodiments, when the offset time of the offset timer 250b is equivalent to the one of the corresponding plurality of timer periods that corresponds the one of the plurality of testing timers, synchronize the absolute time in the node 140 based on the absolute time stored by the emergency driver 130 and offset time. According to certain embodiments, wherein the node 140 receives a plurality of testing times from an external electronic device, and wherein the at least one controller 250a determines a plurality of values for the plurality of timers based on the plurality of testing times. According to certain embodiments, a method for keeping time in a luminaire 100 comprises: receiving an absolute time from a node 705; detecting whether the luminaire receives the AC power 710; when the luminaire receives the AC power: charging the battery with DC power generated from the AC power 715; and storing the absolute time from the node in a memory 720; and when the luminaire does not receive AC power: providing battery power from the battery to a light engine 725; starting an offset timer, thereby causing the offset timer to provide an offset time from starting the offset timer 730; and determining the absolute time based at least in part on the offset time stored in the offset timer and the absolute time 735. According to certain embodiments, the method further comprises storing a plurality of testing timers associated with a corresponding plurality of test periods 805; detecting when one of the plurality of testing timers expires 815; and responsive to detecting that one of the plurality of timers expires: cause the battery to provide battery power to the light engine 820; starting the offset timer 825; and when the offset time of the offset timer is equivalent to a one of the corresponding plurality of timer periods that corresponds the one of 2023PF80435 19 the plurality of testing timers 830: causing the battery to discontinue providing battery power to the light engine 835. According to certain embodiments, the method further comprises when the offset time of the offset timer is equivalent to the one of the corresponding plurality of timer periods that corresponds the one of the plurality of testing timers, synchronizing the absolute time in the node based on the absolute time stored by the emergency driver and offset time 840. According to certain embodiments, the method further comprises: receiving a plurality of testing times from an external electronic device by the node, and determining a plurality of values for the plurality of timers based on the plurality of testing times. According to an embodiment, a method according to various embodiments of the disclosure may be included and provided in a computer program product. The computer program product may be traded as a product between a seller and a buyer. The computer program product may be distributed in the form of a machine-readable storage medium (e.g., compact disc read only memory (CD-ROM)), or be distributed (e.g., downloaded or uploaded) online via an application store (e.g., PlayStoreTM), or between two user devices (e.g., smart phones) directly. If distributed online, at least part of the computer program product may be temporarily generated or at least temporarily stored in the machine-readable storage medium, such as memory of the manufacturer's server, a server of the application store, or a relay server. According to various embodiments, each component (e.g., a module or a program) of the above-described components may include a single entity or multiple entities. According to various embodiments, at least one of the above-described components may be omitted, or at least one other components may be added. Alternatively or additionally, a plurality of components (e.g., modules or programs) may be integrated into a single component. In such a case, according to various embodiments, the integrated component may still perform at least one functions of each of the plurality of components in the same or similar manner as they are performed by a corresponding one of the plurality of components before the integration. According to various embodiments, operations performed by the module, the program, or another component may be carried out sequentially, in parallel, repeatedly, or heuristically, or at least one of the operations may be executed in a different order or omitted, or at least one other operations may be added. While at least one embodiments of the disclosure have been described with reference to the figures, it will be understood by those of ordinary skill in the art that various 2023PF80435 20 changes in form and details may be made therein without departing from the spirit and scope as defined by the following claims.

Claims

2023PF80435 21 CLAIMS:

1. A luminaire (100) comprising:a node (140) configured to keep absolute time and transmit the absolute time; a light engine (110) comprising a plurality of lights; a driver (120) configured to receive AC power from a power outlet (150), convert the AC power to DC power, and provide the DC power to the light engine (110); and an emergency driver (130) including a battery (230) and an offset timer (250b), wherein the emergency driver (130) is configured to:- detect whether the luminaire (100)receives the AC power;- when the luminaire (100)receives the AC power, charge the battery (230) andstore the absolute time from the node; and- when the luminaire (100) does not receive the AC power:- provide battery power from the battery (230) to the light engine (110);record the absolute time when the luminaire (100) stops receiving the AC power and start anoffset timer (250b), wherein the offset timer (250b) provides an amount of elapsed offsettime from recorded absolute time; and -determine the a current absolute time based at least in part on the offset timestored in the offset timer (250b) and the recorded absolute time.

2. The luminaire (100) of claim 1, wherein the node (140) further comprises aBluetooth Low Energy (BLE) transceiver, and wherein the node (140) is adapted to keep the absolute time by synchronizing with an external electronic device.

3. The luminaire (100) of claim 6, wherein the node (140) is configured toreceive the absolute time from an external master node.

4. The luminaire (100) of claim 1, wherein the node (140) comprises aconnectivity node (510), the emergency driver (130) comprises a heartbeat timer.2023PF80435 225. The luminaire (100) of claim 4, wherein store the absolute time from the nodecomprises programming the heartbeat timer with the connectivity node (510).

6. The luminaire (100) of claim 1, wherein the emergency driver (130) furthercomprises: at least one controller (250a); memory (250b) storing a plurality of testing timers associated with a corresponding plurality of test periods; wherein the at least one controller (250a) is configured to: -detect when one of the plurality of testing timers expires; and- responsive to detecting that one of the plurality of testing timers expires:- cause the battery (230) to provide battery power to the light engine(110); and -start the offset timer (250b); and- when the offset time of the offset timer (250b) is equivalent to one ofthe corresponding plurality of test periods that corresponds the one of the plurality of testing timers: cause the battery (230) to discontinue providing battery power to the light engine (110).

7. The luminaire (100) of claim 6, wherein when the offset time of the offsettimer (250b) is equivalent to the one of the corresponding plurality of test periods that corresponds the one of the plurality of testing timers, synchronize the absolute time in the node (140) based on the absolute time stored by the emergency driver (130) and the offset time.

8. The luminaire (100) of claim 6, wherein the node (140) receives a plurality oftesting times from an external electronic device, and wherein the at least one controller (250a) determines a plurality of values for the plurality of testing timers based on the plurality of testing times.

9. A method for keeping time in a luminaire (100), the method comprising:receiving an absolute time from a node (705); detecting whether the luminaire receives AC power (710);2023PF80435 23 when the luminaire receives the AC power: charging a battery with DC power generated from the AC power (715); and storing the absolute time from the node in a memory (720); and when the luminaire does not receive AC power: recording the absolute time when the luminaire (100) stops receiving the AC power providing battery power from the battery to a light engine (725); starting an offset timer, thereby causing the offset timer to provide an offset time from the recorded absolute time; and determining a current absolute time based at least in part on the offset time stored in the offset timer and the recorded absolute time.

10. The method of claim 9, further comprising:storing a plurality of testing timers associated with a corresponding plurality of test periods (805); detecting when one of the plurality of testing timers expires (815); and responsive to detecting that one of the plurality of testing timers expires: -cause the battery to provide battery power to the light engine (820);- starting the offset timer (825); and- when the offset time of the offset timer is equivalent to a one of thecorresponding plurality of test periods that corresponds the one of the plurality of testing timers: causing the battery to discontinue providing battery power to the light engine (835).

11. The method of claim 9, further comprising:when the offset time of the offset timer is equivalent to the one of the corresponding plurality of test periods that corresponds the one of the plurality of testing timers, synchronizing the absolute time in the node based on the absolute time stored by an emergency driver and the offset time (840).2023PF80435 2412. The method of claim 9, further comprising:receiving a plurality of testing times from an external electronic device by the node (705), and determining a plurality of values for the plurality of testing timers based on the plurality of testing times.

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