INTERNET OF THINGS (IOT) MOISTURE SENSOR

BACKGROUND

Field of the Invention

[0001] This invention relates generally to the field of computer systems. More particularly, the invention relates to a system and method for an Internet of Things (IoT) moisture sensor.

Description of the Related Art

[0002] The "Internet of Things" refers to the interconnection of uniquely-identifiable embedded devices within the Internet infrastructure. Ultimately, IoT is expected to result in new, wide-ranging types of applications in which virtually any type of physical thing may provide information about itself or its surroundings and/or may be controlled remotely via client devices over the Internet.

[0003] Moisture sensors are currently available which measure the moisture content of the surrounding environment. In one common form, the sensor is formed with a long metal spike which is forced into the ground to measure moisture of the surrounding soil. A moisture level indicator coupled to at the top of the spike provides an indication of the moisture level.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] A better understanding of the present invention can be obtained from the following detailed description in conjunction with the following drawings, in which:

[0005] FIGS. 1 A-B illustrates different embodiments of an IoT system architecture;

[0006] FIG. 2 illustrates an IoT device in accordance with one embodiment of the invention;

[0007] FIG. 3 illustrates an IoT hub in accordance with one embodiment of the invention;

[0008] FIG. 4A-B illustrate embodiments of the invention for controlling and collecting data from IoT devices, and generating notifications;

[0009] FIG. 5 illustrates embodiments of the invention for collecting data from IoT devices and generating notifications from an IoT hub and/or IoT service;

[0010] FIG. 6 illustrates embodiments of the invention which implements improved security techniques such as encryption and digital signatures;

[0011] FIG. 7 illustrates one embodiment of an architecture in which a subscriber identity module (SIM) is used to store keys on IoT devices; [0012] FIG. 8A illustrates one embodiment in which loT devices are registered using barcodes or QR codes;

[0013] FIG. 8B illustrates one embodiment in which pairing is performed using barcodes or QR codes;

[0014] FIG. 9 illustrates one embodiment of a method for programming a SIM using an loT hub;

[0015] FIG. 10 illustrates one embodiment of a method for registering an loT device with an loT hub and loT service;

[0016] FIG. 11 illustrates one embodiment of a method for encrypting data to be transmitted to an loT device;

[0017] FIG. 12 illustrates a system architecture in accordance with one embodiment of the invention;

[0018] FIG. 13 illustrates an loT moisture sensor in accordance with one

embodiment of the invention;

[0019] FIGS. 14A-B illustrates a form factor for one embodiment of the loT moisture sensor;

[0020] FIG. 15 illustrates an loT moisture sensor with an exemplary water absorption attachment such as a sponge;

[0021] FIG. 16 illustrates an loT moisture sensor with an exemplary spike attachment; and

[0022] FIG. 17 illustrates an loT moisture sensor with an exemplary parallel conductor attachment.

DETAILED DESCRIPTION

[0023] In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the invention described below. It will be apparent, however, to one skilled in the art that the embodiments of the invention may be practiced without some of these specific details. In other instances, well-known structures and devices are shown in block diagram form to avoid obscuring the underlying principles of the embodiments of the invention.

[0024] One embodiment of the invention comprises an Internet of Things (loT) platform which may be utilized by developers to design and build new loT devices and applications. In particular, one embodiment includes a base hardware/software platform for loT devices including a predefined networking protocol stack and an loT hub through which the loT devices are coupled to the Internet. In addition, one embodiment includes an loT service through which the loT hubs and connected loT devices may be accessed and managed as described below. In addition, one embodiment of the loT platform includes an loT app or Web application (e.g., executed on a client device) to access and configured the loT service, hub and connected devices. Existing online retailers and other Website operators may leverage the loT platform described herein to readily provide unique loT functionality to existing user bases.

[0025] Figure 1 A illustrates an overview of an architectural platform on which embodiments of the invention may be implemented. In particular, the illustrated embodiment includes a plurality of loT devices 101 -105 communicatively coupled over local communication channels 130 to a central loT hub 1 10 which is itself

communicatively coupled to an loT service 120 over the Internet 220. Each of the loT devices 101 -105 may initially be paired to the loT hub 1 10 (e.g., using the pairing techniques described below) in order to enable each of the local communication channels 130. In one embodiment, the loT service 120 includes an end user database 122 for maintaining user account information and data collected from each user's loT devices. For example, if the loT devices include sensors (e.g., temperature sensors, accelerometers, heat sensors, motion detectore, etc), the database 122 may be continually updated to store the data collected by the loT devices 101 -105. The data stored in the database 122 may then be made accessible to the end user via the loT app or browser installed on the user's device 135 (or via a desktop or other client computer system) and to web clients (e.g., such as websites 130 subscribing to the loT service 120).

[0026] The loT devices 101 -105 may be equipped with various types of sensors to collect information about themselves and their surroundings and provide the collected information to the loT service 120, user devices 135 and/or external Websites 130 via the loT hub 1 10. Some of the loT devices 101 -105 may perform a specified function in response to control commands sent through the loT hub 1 10. Various specific examples of information collected by the loT devices 101 -105 and control commands are provided below. In one embodiment described below, the loT device 101 is a user input device designed to record user selections and send the user selections to the loT service 120 and/or Website.

[0027] In one embodiment, the loT hub 1 10 includes a cellular radio to establish a connection to the Internet 220 via a cellular service 1 15 such as a 4G (e.g., Mobile WiMAX, LTE) or 5G cellular data service. Alternatively, or in addition, the loT hub 1 10 may include a WiFi radio to establish a WiFi connection through a WiFi access point or router 1 16 which couples the loT hub 1 10 to the Internet (e.g., via an Internet Service Provider providing Internet service to the end user). Of course, it should be noted that the underlying principles of the invention are not limited to any particular type of communication channel or protocol.

[0028] In one embodiment, the loT devices 101 -105 are ultra low-power devices capable of operating for extended periods of time on battery power (e.g., years). To conserve power, the local communication channels 130 may be implemented using a low-power wireless communication technology such as Bluetooth Low Energy (LE). In this embodiment, each of the loT devices 101 -105 and the loT hub 1 10 are equipped with Bluetooth LE radios and protocol stacks.

[0029] As mentioned, in one embodiment, the loT platform includes an loT app or Web application executed on user devices 135 to allow users to access and configure the connected loT devices 101 -105, loT hub 1 10, and/or loT service 120. In one embodiment, the app or web application may be designed by the operator of a Website 130 to provide loT functionality to its user base. As illustrated, the Website may maintain a user database 131 containing account records related to each user.

[0030] Figure 1 B illustrates additional connection options for a plurality of loT hubs 1 10-1 1 1 , 190 In this embodiment a single user may have multiple hubs 1 10-1 1 1 installed onsite at a single user premises 180 (e.g., the user's home or business). This may be done, for example, to extend the wireless range needed to connect all of the loT devices 101 -105. As indicated, if a user has multiple hubs 1 10, 1 1 1 they may be connected via a local communication channel (e.g., Wifi, Ethernet, Power Line

Networking, etc). In one embodiment, each of the hubs 1 10-1 1 1 may establish a direct connection to the loT service 120 through a cellular 1 15 or WiFi 1 16 connection (not explicitly shown in Figure 1 B). Alternatively, or in addition, one of the loT hubs such as loT hub 1 10 may act as a "master" hub which provides connectivity and/or local services to all of the other loT hubs on the user premises 180, such as loT hub 1 1 1 (as indicated by the dotted line connecting loT hub 1 10 and loT hub 1 1 1 ). For example, the master loT hub 1 10 may be the only loT hub to establish a direct connection to the loT service 120. In one embodiment, only the "master" loT hub 1 10 is equipped with a cellular communication interface to establish the connection to the loT service 120. As such, all communication between the loT service 120 and the other loT hubs 1 1 1 will flow through the master loT hub 1 10. In this role, the master loT hub 1 10 may be provided with additional program code to perform filtering operations on the data exchanged between the other loT hubs 1 1 1 and loT service 120 (e.g., servicing some data requests locally when possible).

[0031] Regardless of how the loT hubs 1 10-1 1 1 are connected, in one embodiment, the loT service 120 will logically associate the hubs with the user and combine all of the attached loT devices 101 -105 under a single comprehensive user interface, accessible via a user device with the installed app 135 (and/or a browser-based interface).

[0032] In this embodiment, the master loT hub 1 10 and one or more slave loT hubs 1 1 1 may connect over a local network which may be a WiFi network 1 16, an Ethernet network, and/or a using power-line communications (PLC) networking (e.g., where all or portions of the network are run through the user's power lines). In addition, to the loT hubs 1 10-1 1 1 , each of the loT devices 101 -105 may be interconnected with the loT hubs 1 10-1 1 1 using any type of local network channel such as WiFi, Ethernet, PLC, or Bluetooth LE, to name a few.

[0033] Figure 1 B also shows an loT hub 190 installed at a second user premises 181 . A virtually unlimited number of such loT hubs 190 may be installed and configured to collect data from loT devices 191 -192 at user premises around the world. In one embodiment, the two user premises 180-181 may be configured for the same user. For example, one user premises 180 may be the user's primary home and the other user premises 181 may be the user's vacation home. In such a case, the loT service 120 will logically associate the loT hubs 1 10-1 1 1 , 190 with the user and combine all of the attached loT devices 101 -105, 191 -192 under a single comprehensive user interface, accessible via a user device with the installed app 135 (and/or a browser-based interface).

[0034] As illustrated in Figure 2, an exemplary embodiment of an loT device 101 includes a memory 210 for storing program code and data 201 -203 and a low power microcontroller 200 for executing the program code and processing the data. The memory 210 may be a volatile memory such as dynamic random access memory (DRAM) or may be a non-volatile memory such as Flash memory. In one embodiment, a non-volatile memory may be used for persistent storage and a volatile memory may be used for execution of the program code and data at runtime. Moreover, the memory 210 may be integrated within the low power microcontroller 200 or may be coupled to the low power microcontroller 200 via a bus or communication fabric. The underlying principles of the invention are not limited to any particular implementation of the memory 210. [0035] As illustrated, the program code may include application program code 203 defining an application-specific set of functions to be performed by the loT device 201 and library code 202 comprising a set of predefined building blocks which may be utilized by the application developer of the loT device 101 . In one embodiment, the library code 202 comprises a set of basic functions required to implement an loT device such as a communication protocol stack 201 for enabling communication between each loT device 101 and the loT hub 1 10. As mentioned, in one embodiment, the

communication protocol stack 201 comprises a Bluetooth LE protocol stack. In this embodiment, Bluetooth LE radio and antenna 207 may be integrated within the low power microcontroller 200. However, the underlying principles of the invention are not limited to any particular communication protocol.

[0036] The particular embodiment shown in Figure 2 also includes a plurality of input devices or sensors 210 to receive user input and provide the user input to the low power microcontroller, which processes the user input in accordance with the application code 203 and library code 202. In one embodiment, each of the input devices include an LED 209 to provide feedback to the end user.

[0037] In addition, the illustrated embodiment includes a battery 208 for supplying power to the low power microcontroller. In one embodiment, a non-chargeable coin cell battery is used. However, in an alternate embodiment, an integrated rechargeable battery may be used (e.g., rechargeable by connecting the loT device to an AC power supply (not shown)).

[0038] A speaker 205 is also provided for generating audio. In one embodiment, the low power microcontroller 299 includes audio decoding logic for decoding a compressed audio stream (e.g., such as an MPEG-4/Advanced Audio Coding (AAC) stream) to generate audio on the speaker 205. Alternatively, the low power microcontroller 200 and/or the application code/data 203 may include digitally sampled snippets of audio to provide verbal feedback to the end user as the user enters selections via the input devices 210.

[0039] In one embodiment, one or more other/alternate I/O devices or sensors 250 may be included on the loT device 101 based on the particular application for which the loT device 101 is designed. For example, an environmental sensor may be included to measure temperature, pressure, humidity, etc. A security sensor and/or door lock opener may be included if the loT device is used as a security device. Of course, these examples are provided merely for the purposes of illustration. The underlying principles of the invention are not limited to any particular type of loT device. In fact, given the highly programmable nature of the low power microcontroller 200 equipped with the library code 202, an application developer may readily develop new application code 203 and new I/O devices 250 to interface with the low power microcontroller for virtually any type of loT application.

[0040] In one embodiment, the low power microcontroller 200 also includes a secure key store for storing encryption keys for encrypting communications and/or generating signatures. Alternatively, the keys may be secured in a subscriber identify module (SIM).

[0041] A wakeup receiver 207 is included in one embodiment to wake the loT device from an ultra low power state in which it is consuming virtually no power. In one embodiment, the wakeup receiver 207 is configured to cause the loT device 101 to exit this low power state in response to a wakeup signal received from a wakeup transmitter 307 configured on the loT hub 1 10 as shown in Figure 3. In particular, in one embodiment, the transmitter 307 and receiver 207 together form an electrical resonant transformer circuit such as a Tesla coil. In operation, energy is transmitted via radio frequency signals from the transmitter 307 to the receiver 207 when the hub 1 10 needs to wake the loT device 101 from a very low power state. Because of the energy transfer, the loT device 101 may be configured to consume virtually no power when it is in its low power state because it does not need to continually "listen" for a signal from the hub (as is the case with network protocols which allow devices to be awakened via a network signal). Rather, the microcontroller 200 of the loT device 101 may be configured to wake up after being effectively powered down by using the energy electrically transmitted from the transmitter 307 to the receiver 207.

[0042] As illustrated in Figure 3, the loT hub 1 10 also includes a memory 317 for storing program code and data 305 and hardware logic 301 such as a microcontroller for executing the program code and processing the data. A wide area network (WAN) interface 302 and antenna 310 couple the loT hub 1 10 to the cellular service 1 15.

Alternatively, as mentioned above, the loT hub 1 10 may also include a local network interface (not shown) such as a WiFi interface (and WiFi antenna) or Ethernet interface for establishing a local area network communication channel. In one embodiment, the hardware logic 301 also includes a secure key store for storing encryption keys for encrypting communications and generating/verifying signatures. Alternatively, the keys may be secured in a subscriber identify module (SIM).

[0043] A local communication interface 303 and antenna 31 1 establishes local communication channels with each of the loT devices 101 -105. As mentioned above, in one embodiment, the local communication interface 303/antenna 31 1 implements the Bluetooth LE standard. However, the underlying principles of the invention are not limited to any particular protocols for establishing the local communication channels with the loT devices 101 -105. Although illustrated as separate units in Figure 3, the WAN interface 302 and/or local communication interface 303 may be embedded within the same chip as the hardware logic 301 .

[0044] In one embodiment, the program code and data includes a communication protocol stack 308 which may include separate stacks for communicating over the local communication interface 303 and the WAN interface 302. In addition, device pairing program code and data 306 may be stored in the memory to allow the loT hub to pair with new loT devices. In one embodiment, each new loT device 101 -105 is assigned a unique code which is communicated to the loT hub 1 10 during the pairing process. For example, the unique code may be embedded in a barcode on the loT device and may be read by the barcode reader 106 or may be communicated over the local

communication channel 130. In an alternate embodiment, the unique ID code is embedded magnetically on the loT device and the loT hub has a magnetic sensor such as an radio frequency ID (RFID) or near field communication (NFC) sensor to detect the code when the loT device 101 is moved within a few inches of the loT hub 1 10.

[0045] In one embodiment, once the unique ID has been communicated, the loT hub 1 10 may verify the unique ID by querying a local database (not shown), performing a hash to verify that the code is acceptable, and/or communicating with the loT service 120, user device 135 and/or Website 130 to validate the ID code. Once validated, in one embodiment, the loT hub 1 10 pairs the loT device 101 and stores the pairing data in memory 317 (which, as mentioned, may include non-volatile memory). Once pairing is complete, the loT hub 1 10 may connect with the loT device 101 to perform the various loT functions described herein.

[0046] In one embodiment, the organization running the loT service 120 may provide the loT hub 1 10 and a basic hardware/software platform to allow developers to easily design new loT services. In particular, in addition to the loT hub 1 10, developers may be provided with a software development kit (SDK) to update the program code and data 305 executed within the hub 1 10. In addition, for loT devices 101 , the SDK may include an extensive set of library code 202 designed for the base loT hardware (e.g., the low power microcontroller 200 and other components shown in Figure 2) to facilitate the design of various different types of applications 101 . In one embodiment, the SDK includes a graphical design interface in which the developer needs only to specify input and outputs for the loT device. All of the networking code, including the communication stack 201 that allows the loT device 101 to connect to the hub 1 10 and the service 120, is already in place for the developer. In addition, in one embodiment, the SDK also includes a library code base to facilitate the design of apps for mobile devices (e.g., iPhone and Android devices).

[0047] In one embodiment, the loT hub 1 10 manages a continuous bi-directional stream of data between the loT devices 101 -105 and the loT service 120. In

circumstances where updates to/from the loT devices 101 -105 are required in real time (e.g., where a user needs to view the current status of security devices or environmental readings), the loT hub may maintain an open TCP socket to provide regular updates to the user device 135 and/or external Websites 130. The specific networking protocol used to provide updates may be tweaked based on the needs of the underlying application. For example, in some cases, where may not make sense to have a continuous bi-directional stream, a simple request/response protocol may be used to gather information when needed.

[0048] In one embodiment, both the loT hub 1 10 and the loT devices 101 -105 are automatically upgradeable over the network. In particular, when a new update is available for the loT hub 1 10 it may automatically download and install the update from the loT service 120. It may first copy the updated code into a local memory, run and verify the update before swapping out the older program code. Similarly, when updates are available for each of the loT devices 101 -105, they may initially be downloaded by the loT hub 1 10 and pushed out to each of the loT devices 101 -105. Each loT device 101 -105 may then apply the update in a similar manner as described above for the loT hub and report back the results of the update to the loT hub 1 10. If the update is successful, then the loT hub 1 10 may delete the update from its memory and record the latest version of code installed on each loT device (e.g., so that it may continue to check for new updates for each loT device).

[0049] In one embodiment, the loT hub 1 10 is powered via A/C power. In particular, the loT hub 1 10 may include a power unit 390 with a transformer for transforming A/C voltage supplied via an A/C power cord to a lower DC voltage.

[0050] Figure 4A illustrates one embodiment of the invention for performing universal remote control operations using the loT system. In particular, in this embodiment, a set of loT devices 101 -103 are equipped with infrared (IR) and/or radio frequency (RF) blasters 401 -403, respectively, for transmitting remote control codes to control various different types of electronics equipment including air conditioners/heaters 430, lighting systems 431 , and audiovisual equipment 432 (to name just a few). In the embodiment shown in Figure 4A, the loT devices 101 -103 are also equipped with sensors 404-406, respectively, for detecting the operation of the devices which they control, as described below.

[0051] For example, sensor 404 in loT device 101 may be a temperature and/or humidity sensor for sensing the current temperature/humidity and responsively controlling the air conditioner/heater 430 based on a current desired temperature. In this embodiment, the air conditioner/heater 430 is one which is designed to be controlled via a remote control device (typically a remote control which itself has a temperature sensor embedded therein). In one embodiment, the user provides the desired temperature to the loT hub 1 10 via an app or browser installed on a user device 135. Control logic 412 executed on the loT hub 1 10 receives the current

temperature/humidity data from the sensor 404 and responsively transmits commands to the loT device 101 to control the IR/RF blaster 401 in accordance with the desired temperature/humidity. For example, if the temperature is below the desired

temperature, then the control logic 412 may transmit a command to the air

conditioner/heater via the IR/RF blaster 401 to increase the temperature (e.g., either by turning off the air conditioner or turning on the heater). The command may include the necessary remote control code stored in a database 413 on the loT hub 1 10.

Alternatively, or in addition, the loT service 421 may implement control logic 421 to control the electronics equipment 430-432 based on specified user preferences and stored control codes 422.

[0052] loT device 102 in the illustrated example is used to control lighting 431 . In particular, sensor 405 in loT device 102 may photosensor or photodetector configured to detect the current brightness of the light being produced by a light fixture 431 (or other lighting apparatus). The user may specify a desired lighting level (including an indication of ON or OFF) to the loT hub 1 10 via the user device 135. In response, the control logic 412 will transmit commands to the IR/RF blaster 402 to control the current brightness level of the lights 431 (e.g., increasing the lighting if the current brightness is too low or decreasing the lighting if the current brightness is too high; or simply turning the lights ON or OFF).

[0053] loT device 103 in the illustrated example is configured to control audiovisual equipment 432 (e.g., a television, A/V receiver, cable/satellite receiver, AppleTV™, etc). Sensor 406 in loT device 103 may be an audio sensor (e.g., a microphone and associated logic) for detecting a current ambient volume level and/or a photosensor to detect whether a television is on or off based on the light generated by the television (e.g., by measuring the light within a specified spectrum). Alternatively, sensor 406 may include a temperature sensor connected to the audiovisual equipment to detect whether the audio equipment is on or off based on the detected temperature. Once again, in response to user input via the user device 135, the control logic 412 may transmit commands to the audiovisual equipment via the IR blaster 403 of the loT device 103.

[0054] It should be noted that the foregoing are merely illustrative examples of one embodiment of the invention. The underlying principles of the invention are not limited to any particular type of sensors or equipment to be controlled by loT devices.

[0055] In an embodiment in which the loT devices 101 -103 are coupled to the loT hub 1 10 via a Bluetooth LE connection, the sensor data and commands are sent over the Bluetooth LE channel. However, the underlying principles of the invention are not limited to Bluetooth LE or any other communication standard.

[0056] In one embodiment, the control codes required to control each of the pieces of electronics equipment are stored in a database 413 on the loT hub 1 10 and/or a database 422 on the loT service 120. As illustrated in Figure 4B, the control codes may be provided to the loT hub 1 10 from a master database of control codes 422 for different pieces of equipment maintained on the loT service 120. The end user may specify the types of electronic (or other) equipment to be controlled via the app or browser executed on the user device 135 and, in response, a remote control code learning module 491 on the loT hub may retrieve the required IR/RF codes from the remote control code database 492 on the loT service 120 (e.g., identifying each piece of electronic equipment with a unique ID).

[0057] In addition, in one embodiment, the loT hub 1 10 is equipped with an IR/RF interface 490 to allow the remote control code learning module 491 to "learn" new remote control codes directly from the original remote control 495 provided with the electronic equipment. For example, if control codes for the original remote control provided with the air conditioner 430 is not included in the remote control database, the user may interact with the loT hub 1 10 via the app/browser on the user device 135 to teach the loT hub 1 10 the various control codes generated by the original remote control (e.g., increase temperature, decrease temperature, etc). Once the remote control codes are learned they may be stored in the control code database 413 on the loT hub 1 10 and/or sent back to the loT service 120 to be included in the central remote control code database 492 (and subsequently used by other users with the same air conditioner unit 430). [0058] In one embodiment, each of the loT devices 101 -103 have an extremely small form factor and may be affixed on or near their respective electronics equipment 430-432 using double-sided tape, a small nail, a magnetic attachment, etc. For control of a piece of equipment such as the air conditioner 430, it would be desirable to place the loT device 101 sufficiently far away so that the sensor 404 can accurately measure the ambient temperature in the home (e.g., placing the loT device directly on the air conditioner would result in a temperature measurement which would be too low when the air conditioner was running or too high when the heater was running). In contrast, the loT device 102 used for controlling lighting may be placed on or near the lighting fixture 431 for the sensor 405 to detect the current lighting level.

[0059] In addition to providing general control functions as described, one embodiment of the loT hub 1 10 and/or loT service 120 transmits notifications to the end user related to the current status of each piece of electronics equipment. The notifications, which may be text messages and/or app-specific notifications, may then be displayed on the display of the user's mobile device 135. For example, if the user's air conditioner has been on for an extended period of time but the temperature has not changed, the loT hub 1 10 and/or loT service 120 may send the user a notification that the air conditioner is not functioning properly. If the user is not home (which may be detected via motion sensors or based on the user's current detected location), and the sensors 406 indicate that audiovisual equipment 430 is on or sensors 405 indicate that the lights are on, then a notification may be sent to the user, asking if the user would like to turn off the audiovisual equipment 432 and/or lights 431 . The same type of notification may be sent for any equipment type.

[0060] Once the user receives a notification, he/she may remotely control the electronics equipment 430-432 via the app or browser on the user device 135. In one embodiment, the user device 135 is a touchscreen device and the app or browser displays an image of a remote control with user-selectable buttons for controlling the equipment 430-432. Upon receiving a notification, the user may open the graphical remote control and turn off or adjust the various different pieces of equipment. If connected via the loT service 120, the user's selections may be forwarded from the loT service 120 to the loT hub 1 10 which will then control the equipment via the control logic 412. Alternatively, the user input may be sent directly to the loT hub 1 10 from the user device 135.

[0061] In one embodiment, the user may program the control logic 412 on the loT hub 1 10 to perform various automatic control functions with respect to the electronics equipment 430-432. In addition to maintaining a desired temperature, brightness level, and volume level as described above, the control logic 412 may automatically turn off the electronics equipment if certain conditions are detected. For example, if the control logic 412 detects that the user is not home and that the air conditioner is not functioning, it may automatically turn off the air conditioner. Similarly, if the user is not home, and the sensors 406 indicate that audiovisual equipment 430 is on or sensors 405 indicate that the lights are on, then the control logic 412 may automatically transmit commands via the IR/RF blasters 403 and 402, to turn off the audiovisual equipment and lights, respectively.

[0062] Figure 5 illustrates additional embodiments of loT devices 104-105 equipped with sensors 503-504 for monitoring electronic equipment 530-531 . In particular, the loT device 104 of this embodiment includes a temperature sensor 503 which may be placed on or near a stove 530 to detect when the stove has been left on. In one embodiment, the loT device 104 transmits the current temperature measured by the temperature sensor 503 to the loT hub 1 10 and/or the loT service 120. If the stove is detected to be on for more than a threshold time period (e.g., based on the measured temperature), then control logic 512 may transmit a notification to the end user's device 135 informing the user that the stove 530 is on. In addition, in one embodiment, the loT device 104 may include a control module 501 to turn off the stove, either in response to receiving an instruction from the user or automatically (if the control logic 512 is programmed to do so by the user). In one embodiment, the control logic 501 comprises a switch to cut off electricity or gas to the stove 530. However, in other embodiments, the control logic 501 may be integrated within the stove itself.

[0063] Figure 5 also illustrates an loT device 105 with a motion sensor 504 for detecting the motion of certain types of electronics equipment such as a washer and/or dryer. Another sensor that may be used is an audio sensor (e.g., microphone and logic) for detecting an ambient volume level. As with the other embodiments described above, this embodiment may transmit notifications to the end user if certain specified conditions are met (e.g., if motion is detected for an extended period of time, indicating that the washer/dryer are not turning off). Although not shown in Figure 5, loT device 105 may also be equipped with a control module to turn off the washer/dryer 531 (e.g., by switching off electric/gas), automatically, and/or in response to user input.

[0064] In one embodiment, a first loT device with control logic and a switch may be configured to turn off all power in the user's home and a second loT device with control logic and a switch may be configured to turn off all gas in the user's home. loT devices with sensors may then be positioned on or near electronic or gas-powered equipment in the user's home. If the user is notified that a particular piece of equipment has been left on (e.g., the stove 530), the user may then send a command to turn off all electricity or gas in the home to prevent damage. Alternatively, the control logic 512 in the loT hub 1 10 and/or the loT service 120 may be configured to automatically turn off electricity or gas in such situations.

[0065] In one embodiment, the loT hub 1 10 and loT service 120 communicate at periodic intervals. If the loT service 120 detects that the connection to the loT hub 1 10 has been lost (e.g., by failing to receive a request or response from the loT hub for a specified duration), it will communicate this information to the end user's device 135 (e.g., by sending a text message or app-specific notification).

EMBODIMENTS FOR I MPROVED SECURITY

[0066] In one embodiment, the low power microcontroller 200 of each loT device 101 and the low power logic/microcontroller 301 of the loT hub 1 10 include a secure key store for storing encryption keys used by the embodiments described below (see, e.g., Figures 6-11 and associated text). Alternatively, the keys may be secured in a subscriber identify module (SIM) as discussed below.

[0067] Figure 6 illustrates a high level architecture which uses public key infrastructure (PKI) techniques and/or symmetric key exchange/encryption techniques to encrypt communications between the loT Service 120, the loT hub 1 10 and the loT devices 101 -102.

[0068] Embodiments which use public/private key pairs will first be described, followed by embodiments which use symmetric key exchange/encryption techniques. In particular, in an embodiment which uses PKI, a unique public/private key pair is associated with each loT device 101 -102, each loT hub 1 10 and the loT service 120. In one embodiment, when a new loT hub 1 10 is set up, its public key is provided to the loT service 120 and when a new loT device 101 is set up, it's public key is provided to both the loT hub 1 10 and the loT service 120. Various techniques for securely exchanging the public keys between devices are described below. In one embodiment, all public keys are signed by a master key known to all of the receiving devices (i.e., a form of certificate) so that any receiving device can verify the validity of the public keys by validating the signatures. Thus, these certificates would be exchanged rather than merely exchanging the raw public keys.

[0069] As illustrated, in one embodiment, each loT device 101 , 102 includes a secure key storage 601 , 603, respectively, for security storing each device's private key. Security logic 602, 1304 then utilizes the securely stored private keys to perform the encryption/decryption operations described herein. Similarly, the loT hub 1 10 includes a secure storage 61 1 for storing the loT hub private key and the public keys of the loT devices 101 -102 and the loT service 120; as well as security logic 612 for using the keys to perform encryption/decryption operations. Finally, the loT service 120 may include a secure storage 621 for security storing its own private key, the public keys of various loT devices and loT hubs, and a security logic 613 for using the keys to encrypt/decrypt communication with loT hubs and devices. In one embodiment, when the loT hub 1 10 receives a public key certificate from an loT device it can verify it (e.g., by validating the signature using the master key as described above), and then extract the public key from within it and store that public key in it's secure key store 61 1 .

[0070] By way of example, in one embodiment, when the loT service 120 needs to transmit a command or data to an loT device 101 (e.g., a command to unlock a door, a request to read a sensor, data to be processed/displayed by the loT device, etc) the security logic 613 encrypts the data/command using the public key of the loT device 101 to generate an encrypted loT device packet. In one embodiment, it then encrypts the loT device packet using the public key of the loT hub 1 10 to generate an loT hub packet and transmits the loT hub packet to the loT hub 1 10. In one embodiment, the service 120 signs the encrypted message with it's private key or the master key mentioned above so that the device 101 can verify it is receiving an unaltered message from a trusted source. The device 101 may then validate the signature using the public key corresponding to the private key and/or the master key. As mentioned above, symmetric key

exchange/encryption techniques may be used instead of public/private key encryption. In these embodiments, rather than privately storing one key and providing a corresponding public key to other devices, the devices may each be provided with a copy of the same symmetric key to be used for encryption and to validate signatures. One example of a symmetric key algorithm is the Advanced Encryption Standard (AES), although the underlying principles of the invention are not limited to any type of specific symmetric keys.

[0071 ] Using a symmetric key implementation, each device 101 enters into a secure key exchange protocol to exchange a symmetric key with the loT hub 1 10. A secure key provisioning protocol such as the Dynamic Symmetric Key Provisioning Protocol

(DSKPP) may be used to exchange the keys over a secure communication channel (see, e.g., Request for Comments (RFC) 6063). However, the underlying principles of the invention are not limited to any particular key provisioning protocol. [0072] Once the symmetric keys have been exchanged, they may be used by each device 101 and the loT hub 1 10 to encrypt communications. Similarly, the loT hub 1 10 and loT service 120 may perform a secure symmetric key exchange and then use the exchanged symmetric keys to encrypt communications. In one embodiment a new symmetric key is exchanged periodically between the devices 101 and the hub 1 10 and between the hub 1 10 and the loT service 120. In one embodiment, a new symmetric key is exchanged with each new communication session between the devices 101 , the hub 1 10, and the service 120 (e.g., a new key is generated and securely exchanged for each communication session). In one embodiment, if the security module 612 in the loT hub is trusted, the service 120 could negotiate a session key with the hub security module 1312 and then the security module 612 would negotiate a session key with each device 120. Messages from the service 120 would then be decrypted and verified in the hub security module 612 before being re-encrypted for transmission to the device 101 .

[0073] In one embodiment, to prevent a compromise on the hub security module 612 a one-time (permanent) installation key may be negotiated between the device 101 and service 120 at installation time. When sending a message to a device 101 the service 120 could first encrypt/MAC with this device installation key, then encrypt/MAC that with the hub's session key. The hub 1 10 would then verify and extract the encrypted device blob and send that to the device.

[0074] In one embodiment of the invention, a counter mechanism is implemented to prevent replay attacks. For example, each successive communication from the device 101 to the hub 1 10 (or vice versa) may be assigned a continually increasing counter value. Both the hub 1 10 and device 101 will track this value and verify that the value is correct in each successive communication between the devices. The same techniques may be implemented between the hub 1 10 and the service 120. Using a counter in this manner would make it more difficult to spoof the communication between each of the devices (because the counter value would be incorrect). However, even without this a shared installation key between the service and device would prevent network (hub) wide attacks to all devices.

[0075] In one embodiment, when using public/private key encryption, the loT hub 1 10 uses its private key to decrypt the loT hub packet and generate the encrypted loT device packet, which it transmits to the associated loT device 101 . The loT device 101 then uses its private key to decrypt the loT device packet to generate the command/data originated from the loT service 120. It may then process the data and/or execute the command. Using symmetric encryption, each device would encrypt and decrypt with the shared symmetric key. If either case, each transmitting device may also sign the message with it's private key so that the receiving device can verify it's authenticity.

[0076] A different set of keys may be used to encrypt communication from the loT device 101 to the loT hub 1 10 and to the loT service 120. For example, using a public/private key arrangement, in one embodiment, the security logic 602 on the loT device 101 uses the public key of the loT hub 1 10 to encrypt data packets sent to the loT hub 1 10. The security logic 612 on the loT hub 1 10 may then decrypt the data packets using the loT hub's private key. Similarly, the security logic 602 on the loT device 101 and/or the security logic 612 on the loT hub 1 10 may encrypt data packets sent to the loT service 120 using the public key of the loT service 120 (which may then be decrypted by the security logic 613 on the loT service 120 using the service's private key). Using symmetric keys, the device 101 and hub 1 10 may share a symmetric key while the hub and service 120 may share a different symmetric key.

[0077] While certain specific details are set forth above in the description above, it should be noted that the underlying principles of the invention may be implemented using various different encryption techniques. For example, while some embodiments discussed above use asymmetric public/private key pairs, an alternate embodiment may use symmetric keys securely exchanged between the various loT devices 101 -102, loT hubs 1 10, and the loT service 120. Moreover, in some embodiments, the data/command itself is not encrypted, but a key is used to generate a signature over the data/command (or other data structure). The recipient may then use its key to validate the signature.

[0078] As illustrated in Figure 7, in one embodiment, the secure key storage on each loT device 101 is implemented using a programmable subscriber identity module (SIM) 701 . In this embodiment, the loT device 101 may initially be provided to the end user with an un-programmed SIM card 701 seated within a SIM interface 700 on the loT device 101 . In order to program the SIM with a set of one or more encryption keys, the user takes the programmable SIM card 701 out of the SIM interface 500 and inserts it into a SIM programming interface 702 on the loT hub 1 10. Programming logic 725 on the loT hub then securely programs the SIM card 701 to register/pair the loT device 101 with the loT hub 1 10 and loT service 120. In one embodiment, a public/private key pair may be randomly generated by the programming logic 725 and the public key of the pair may then be stored in the loT hub's secure storage device 41 1 while the private key may be stored within the programmable SIM 701 . In addition, the programming logic 525 may store the public keys of the loT hub 1 10, the loT service 120, and/or any other loT devices 101 on the SIM card 601 (to be used by the security logic 1302 on the loT device 101 to encrypt outgoing data). Once the SIM 701 is programmed, the new loT device 101 may be provisioned with the loT Service 120 using the SIM as a secure identifier (e.g., using existing techniques for registering a device using a SIM). Following provisioning, both the loT hub 1 10 and the loT service 120 will securely store a copy of the loT device's public key to be used when encrypting communication with the loT device 101 .

[0079] The techniques described above with respect to Figure 7 provide enormous flexibility when providing new loT devices to end users. Rather than requiring a user to directly register each SIM with a particular service provider upon sale/purchase (as is currently done), the SIM may be programmed directly by the end user via the loT hub 1 10 and the results of the programming may be securely communicated to the loT service 120. Consequently, new loT devices 101 may be sold to end users from online or local retailers and later securely provisioned with the loT service 120.

[0080] While the registration and encryption techniques are described above within the specific context of a SIM (Subscriber Identity Module), the underlying principles of the invention are not limited to a "SIM" device. Rather, the underlying principles of the invention may be implemented using any type of device having secure storage for storing a set of encryption keys. Moreover, while the embodiments above include a removable SIM device, in one embodiment, the SIM device is not removable but the loT device itself may be inserted within the programming interface 702 of the loT hub 1 10.

[0081 ] In one embodiment, rather than requiring the user to program the SIM (or other device), the SIM is pre-programmed into the loT device 101 , prior to distribution to the end user. In this embodiment, when the user sets up the loT device 101 , various techniques described herein may be used to securely exchange encryption keys between the loT hub 1 10/loT service 120 and the new loT device 101 .

[0082] For example, as illustrated in Figure 8A each loT device 101 or SIM 401 may be packaged with a barcode or QR code 701 uniquely identifying the loT device 101 and/or SIM 701 . In one embodiment, the barcode or QR code 801 comprises an encoded representation of the public key for the loT device 101 or SIM 1001 .

Alternatively, the barcode or QR code 801 may be used by the loT hub 1 10 and/or loT service 120 to identify or generate the public key (e.g., used as a pointer to the public key which is already stored in secure storage). The barcode or QR code 601 may be printed on a separate card (as shown in Figure 8A) or may be printed directly on the loT device itself. Regardless of where the barcode is printed, in one embodiment, the loT hub 1 10 is equipped with a barcode reader 206 for reading the barcode and providing the resulting data to the security logic 1012 on the loT hub 1 10 and/or the security logic 1013 on the loT service 120. The security logic 1012 on the loT hub 1 10 may then store the public key for the loT device within its secure key storage 101 1 and the security logic 1013 on the loT service 120 may store the public key within its secure storage 1021 (to be used for subsequent encrypted communication).

[0083] In one embodiment, the data contained in the barcode or QR code 801 may also be captured via a user device 135 (e.g., such as an iPhone or Android device) with an installed loT app or browser-based applet designed by the loT service provider. Once captured, the barcode data may be securely communicated to the loT service 120 over a secure connection (e.g., such as a secure sockets layer (SSL) connection). The barcode data may also be provided from the client device 135 to the loT hub 1 10 over a secure local connection (e.g., over a local WiFi or Bluetooth LE connection).

[0084] The security logic 1002 on the loT device 101 and the security logic 1012 on the loT hub 1 10 may be implemented using hardware, software, firmware or any combination thereof. For example, in one embodiment, the security logic 1002, 1012 is implemented within the chips used for establishing the local communication channel 130 between the loT device 101 and the loT hub 1 10 (e.g., the Bluetooth LE chip if the local channel 130 is Bluetooth LE). Regardless of the specific location of the security logic 1002, 1012, in one embodiment, the security logic 1002, 1012 is designed to establish a secure execution environment for executing certain types of program code. This may be implemented, for example, by using TrustZone technology (available on some ARM processors) and/or Trusted Execution Technology (designed by Intel). Of course, the underlying principles of the invention are not limited to any particular type of secure execution technology.

[0085] In one embodiment, the barcode or QR code 701 may be used to pair each loT device 101 with the loT hub 1 10. For example, rather than using the standard wireless pairing process currently used to pair Bluetooth LE devices, a pairing code embedded within the barcode or QR code 701 may be provided to the loT hub 1 10 to pair the loT hub with the corresponding loT device.

[0086] Figure 8B illustrates one embodiment in which the barcode reader 206 on the loT hub 1 10 captures the barcode/QR code 801 associated with the loT device 101 . As mentioned, the barcode/QR code 801 may be printed directly on the loT device 101 or may be printed on a separate card provided with the loT device 101 . In either case, the barcode reader 206 reads the pairing code from the barcode/QR code 801 and provides the pairing code to the local communication module 880. In one embodiment, the local communication module 880 is a Bluetooth LE chip and associated software, although the underlying principles of the invention are not limited to any particular protocol standard. Once the pairing code is received, it is stored in a secure storage containing pairing data 885 and the loT device 101 and loT hub 1 10 are automatically paired. Each time the loT hub is paired with a new loT device in this manner, the pairing data for that pairing is stored within the secure storage 685. In one embodiment, once the local communication module 880 of the loT hub 1 10 receives the pairing code, it may use the code as a key to encrypt communications over the local wireless channel with the loT device 101 .

[0087] Similarly, on the loT device 101 side, the local communication module 890 stores pairing data within a local secure storage device 895 indicating the pairing with the loT hub. The pairing data 895 may include the pre-programmed pairing code identified in the barcode/QR code 801 . The pairing data 895 may also include pairing data received from the local communication module 880 on the loT hub 1 10 required for establishing a secure local communication channel (e.g., an additional key to encrypt communication with the loT hub 1 10).

[0088] Thus, the barcode/QR code 801 may be used to perform local pairing in a far more secure manner than current wireless pairing protocols because the pairing code is not transmitted over the air. In addition, in one embodiment, the same barcode/QR code 801 used for pairing may be used to identify encryption keys to build a secure connection from the loT device 101 to the loT hub 1 10 and from the loT hub 1 10 to the loT service 120.

[0089] A method for programming a SIM card in accordance with one embodiment of the invention is illustrated in Figure 9. The method may be implemented within the system architecture described above, but is not limited to any particular system architecture.

[0090] At 901 , a user receives a new loT device with a blank SIM card and, at 802, the user inserts the blank SIM card into an loT hub. At 903, the user programs the blank SIM card with a set of one or more encryption keys. For example, as mentioned above, in one embodiment, the loT hub may randomly generate a public/private key pair and store the private key on the SIM card and the public key in its local secure storage. In addition, at 904, at least the public key is transmitted to the loT service so that it may be used to identify the loT device and establish encrypted communication with the loT device. As mentioned above, in one embodiment, a programmable device other than a "SIM" card may be used to perform the same functions as the SIM card in the method shown in Figure 9. [0091 ] A method for integrating a new loT device into a network is illustrated in Figure 10. The method may be implemented within the system architecture described above, but is not limited to any particular system architecture.

[0092] At 1001 , a user receives a new loT device to which an encryption key has been pre-assigned. At 1002, the key is securely provided to the loT hub. As mentioned above, in one embodiment, this involves reading a barcode associated with the loT device to identify the public key of a public/private key pair assigned to the device. The barcode may be read directly by the loT hub or captured via a mobile device via an app or bowser. In an alternate embodiment, a secure communication channel such as a Bluetooth LE channel, a near field communication (NFC) channel or a secure WiFi channel may be established between the loT device and the loT hub to exchange the key. Regardless of how the key is transmitted, once received, it is stored in the secure keystore of the loT hub device. As mentioned above, various secure execution technologies may be used on the loT hub to store and protect the key such as Secure Enclaves, Trusted Execution Technology (TXT), and/or Trustzone. In addition, at 1003, the key is securely transmitted to the loT service which stores the key in its own secure keystore. It may then use the key to encrypt communication with the loT device. One again, the exchange may be implemented using a certificate/signed key. Within the hub 1 10 it is particularly important to prevent modification/addition/ removal of the stored keys.

[0093] A method for securely communicating commands/data to an loT device using public/private keys is illustrated in Figure 11. The method may be implemented within the system architecture described above, but is not limited to any particular system architecture.

[0094] At 1 101 , the loT service encrypts the data/commands using the loT device public key to create an loT device packet. It then encrypts the loT device packet using loT hub's public key to create the loT hub packet (e.g., creating an loT hub wrapper around the loT device packet). At 1 102, the loT service transmits the loT hub packet to the loT hub. At 1 103, the loT hub decrypts the loT hub packet using the loT hub's private key to generate the loT device packet. At 1 104 it then transmits the loT device packet to the loT device which, at 1 105, decrypts the loT device packet using the loT device private key to generate the data/commands. At 1 106, the loT device processes the data/commands.

[0095] In an embodiment which uses symmetric keys, a symmetric key exchange may be negotiated between each of the devices (e.g., each device and the hub and between the hub and the service). Once the key exchange is complete, each transmitting device encrypts and/or signs each transmission using the symmetric key before transmitting data to the receiving device.

SYSTEM AND METHOD FOR AN INTERNET OF THINGS (loT) MOISTURE SENSOR

[0096] One embodiment of the invention comprises an Internet of Things (loT) moisture sensor which may be coupled to an loT system to provide moisture readings and/or control watering. Figure 12, for example, illustrates a system architecture with three such loT moisture sensor devices 1201 -1203 which may be used for various moisture detection applications. For example, in one embodiment, one or more of the loT moisture sensor devices 1201 -1203 may be placed into the soil (e.g., near grassy areas, bushes, flowers, etc) and report back the current moisture level to the loT cloud service 1220 via the loT hub 1205. The user may then log in via the user device 1210 via an app or application to view the moisture levels. In addition, in one embodiment, one or more watering system loT devices 1204 may be configured to turn on/off the various sprinklers and slow drip watering devices in response to the moisture data provided by the loT moisture sensors 1201 -1203. For example, in one embodiment, when the moisture level of a particular moisture sensor 1201 reaches a user-specified threshold, watering control logic 1216 on the loT cloud service 1220 may transmit a command to turn on the sprinkler or other watering device supplying water to the area measured by the loT moisture sensor 1201 . While shown in the loT cloud service 1220 for the purpose of explanation, the watering control logic 1216 may also be

implemented on the loT hub 1205 or directly within the watering system loT devices 1204.

[0097] The interaction between the various system components shown in Figure 12 may occur as described above. For example, the loT hub 1205 communicates with the loT devices 1201 -1203 over low power wireless communication channels such as Bluetooth Low Energy (BTLE) channels and, in one embodiment, establishes a communication channel with the loT cloud service 1220.

[0098] As illustrated, the loT cloud service 1220 may include an loT device database 1230 comprising database records for each of the loT devices 1201 -1204 and loT hubs 1205 configured in the system (which may include a plurality of loT hubs and devices not shown in Figure 12). loT device management logic 1215 creates the database records for new loT devices and updates the loT device records in response to data transmitted by each of the loT devices 1201 -1204. [0099] The ΙοΤ device management logic 1215 may also implement the various security/encryption functions described above to add new devices to the system (e.g., using QR codes/barcodes) and use keys to encrypt communications and/or generate digital signatures when communicating with the loT devices 1201 -1204. In one embodiment, a user may access information related to each of the loT devices 1201 - 1204 and/or control the devices via an app installed on a user device 1210 which may be a smartphone device such as an Android® device or iPhone®. In addition, the user may access and control the loT devices via a browser or application installed on a desktop or laptop computer.

[00100] In one embodiment, control signals transmitted from the app or application on the user device 1210 are passed to the loT cloud service 1220 over the Internet 1222, then forwarded from the loT cloud service 1220 to the loT hub 1205 and from the loT hub 1205 to one or more of the loT devices 1201 -1204. Of course, the underlying principles of the invention are not limited to any particular manner in which the user accesses/controls the various loT devices 1201 -1204. For example, the user may transmit a control signal to turn on/off watering system loT devices 1204.

[00101 ] Embodiments of the invention may include various steps, which have been described above. The steps may be embodied in machine-executable instructions which may be used to cause a general-purpose or special-purpose processor to perform the steps. Alternatively, these steps may be performed by specific hardware components that contain hardwired logic for performing the steps, or by any

combination of programmed computer components and custom hardware components.

[00102] As described herein, instructions may refer to specific configurations of hardware such as application specific integrated circuits (ASICs) configured to perform certain operations or having a predetermined functionality or software instructions stored in memory embodied in a non-transitory computer readable medium. Thus, the techniques shown in the figures can be implemented using code and data stored and executed on one or more electronic devices (e.g., an end station, a network element, etc.). Such electronic devices store and communicate (internally and/or with other electronic devices over a network) code and data using computer machine-readable media, such as non-transitory computer machine-readable storage media (e.g., magnetic disks; optical disks; random access memory; read only memory; flash memory devices; phase-change memory) and transitory computer machine-readable

communication media (e.g., electrical, optical, acoustical or other form of propagated signals - such as carrier waves, infrared signals, digital signals, etc.). In addition, such electronic devices typically include a set of one or more processors coupled to one or more other components, such as one or more storage devices (non-transitory machine- readable storage media), user input/output devices (e.g., a keyboard, a touchscreen, and/or a display), and network connections. The coupling of the set of processors and other components is typically through one or more busses and bridges (also termed as bus controllers). The storage device and signals carrying the network traffic

respectively represent one or more machine-readable storage media and machine- readable communication media. Thus, the storage device of a given electronic device typically stores code and/or data for execution on the set of one or more processors of that electronic device. Of course, one or more parts of an embodiment of the invention may be implemented using different combinations of software, firmware, and/or hardware.

[00103] Throughout this detailed description, for the purposes of explanation, numerous specific details were set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the invention may be practiced without some of these specific details. In certain instances, well known structures and functions were not described in elaborate detail in order to avoid obscuring the subject matter of the present invention. Accordingly, the scope and spirit of the invention should be judged in terms of the claims which follow.