The Commercial lighting space for many years was dominated with florescent tube lighting. While these provided significant savings over the use of incandescent lighting, they suffered some significant performance, maintenance, and use issues. These included short life span, wide color temperature variation, random flickering & hum, and an inability to dim and save power effectively. In addition, frequently turning the florescent lights on/off based on occupancy significantly decreased lifespan and increased power use during startup which often negated the power saving when the fixture was off.
The development of a commercial LED lighting has prompted a total redesign of how commercial lighting should be approached. This has included the addition of smart controls systems as key element that is used to provide total energy management. These fixtures are now often a networked device. These LED lighting fixtures are the cornerstone of IoT Lighting.
With the introduction of Networking to the LED fixtures, security vulnerabilities need to be considered.
The design these new LED lighting fixtures has many software elements that can provide additional levels of efficiency. This increased efficiency allows power savings of up to 90% over traditional florescent lighting fixtures.
Several standards have emerged to ensure that energy savings will be realized when upgrading to more efficient lighting fixtures. The “Title 24” standard introduced into California is one such specification that these fixtures must comply with to pass code compliance.
This IoT Design will examine the elements used in creating a leading-edge lighting solution.
The lighting solution described here involves many elements that work together to provide a complete solution to Commercial building lighting. Key to the system is the iMatrix IoT Platform. This system includes all elements used to create the total solution.
The system consists of the following items:
1. Fixture Controller and Power Management
a. Cypress WICED Wi Fi Module for Fixture control and communications
b. Cypress PSoC 4 for special sensor processing used with Occupancy detection
2. iMatrix WICED Client to provide Cloud Connectivity for Controls and Sensors
3. iMatrix Mobile Applications for Android and iOS use for provisioning and fixture controls
4. iMatrix Cloud Application for site design, floor plan layouts and fixture placements.
5. iMatrix Cloud Application to monitor and manage deployed fixtures and other sensor elements.
The Fixture controller can be directly integrated into Fixtures or used as a stand-alone controller to manage and control and standard 0-10V dimmable fixture or other
The full system Architecture can be visualized in the following diagram.
Fixture Controller and Power Management
The Fixture Controller and Power Management system consist of three primary Modules:
1. Control Module incorporating Cypress WICED Wi Fi Module, Cypress PSoC Controller
2. Sensors Module
3. Power Module incorporating relay controls, power measurement and dimming controls (in and out)
The following diagrams show block diagrams of the key elements of each section.
The first diagram illustrates the structure of the Control module. This encompass the WICED Wi-Fi Module, PSoC Controller and interfaces to USB Port, I2C BUS, Wireless switch Controller and interfaces to Sensors and Power modules.
The USB port is used during manufacturing and testing to provide diagnostic feedback.
Both the WICED Module and the PSoC Processor have JTAG interfaces that are used during the manufacturing process to load software.
Security Certificates are issued to the device in manufacturing and maybe programmed over the air or directly using the USB port.
The Sensor Module contains sensors that are located close to the exterior of the Light fixture controller that need access to the environment. This includes the support circuitry for the audio sensor.
The Power module supports interfaces to the line power, LED Drivers and Dim Output controls and Wired Dim Inputs controls.
The Power module must pass several UL tests that are applicable for Lighting Fixtures. These systems support a wide supply voltage range and operate commercial 110-277 VAC circuits.
Inventek WICED Wi Fi Module
The Inventek WICED Wi-Fi Module provided the core element in the Fixtures control. This module includes a powerful STM32 Microprocessor coupled with the Cypress Dual Band Wi-Fi and Bluetooth radio sub systems with integrated antennas.
The processor controls all aspects of the Fixtures operation.
The key items that the processor monitors are:
1. Turning Fixture LED Driver ON/OFF
2. Controlling Dim Level of LED Driver
3. Monitoring for Occupancy/Vacancy Condition
4. Daylight Harvesting
5. Monitor Power use
6. Monitor Temperature & Humidity
7. Monitor for Seismic activity
8. Providing a secure network connection to local fixtures and remote servers
9. Provide direct control using BLE wireless switches.
10. Connect to additional BLE Sensors
11. Provide automatic dimming in response to Automatic Demand Reponses systems
12. Provide Over the Air Updates for both the core WICED software elements along with the PSoC 4 processor.
The STM32 processor software was developed using the fully featured Cypress WICED SDK for Wi Fi. This powerful system includes the framework necessary to provide a real-time IoT system with all the functions needed for a networked Lighting fixture.
The standard WICED Software Stack is shown in the following diagram
The Interface to the Wi-Fi and Bluetooth networks use a suite of API calls to manage these communication channels. The Wi-Fi module in conjunction with the WICED SDK provide an Enterprise Wi-Fi IoT Security suite. The light fixture uses IEEE 802.1X for wireless authentication and TLS over TCP for connection to remote iMatrix Servers. Certificates used for the IEEE 802.1X and TLS connections are installed during the manufacturing phase of the product life cycle and are standard elements of the iMatrix Cloud services for Manufacturing.
Local messages sent between fixtures (for group/room occupancy updates) and the Mobile Application utilize the efficient CoAP protocol. These protocol suites are incorporated in the WICED SDK for Wi Fi.
The inclusion of a secure (Over the Air) OTA Update service is a critical element of an IoT product. In addition to upgrading the software of the main processor the system
supports downloading firmware images to slave processors, in this case a Cypress PSoC 4.
The iMatrix WICED Client sits on top of the WICED SDK and use the WICED API to perform iMatrix cloud related services.
The Light Fixture software interfaces with both the WICED API for Timer, peripheral I/O services (GPIO, SPI, I2C, and PWM) and uses the iMatrix API to provide iMatrix Cloud connectivity functions.
The Local CoAP messages are routed through the iMatrix API to allow the Light Fixture to be notified of occupancy conditions of adjoining fixtures that are within their group.
Cypress PSoC 4
The Cypress PSoC combines an ARM M0 processor along with programmable Analog blocks. These elements are shown in the following diagram.
In this design a Cypress PSoC 4 was used to do the heavy lifting of analyzing the activity from a Passive Infra-Red (PIR) Detector and the analysis of the audio monitor. This two-factor system is used to determine occupancy/vacancy. The PIR operates well to detect occupancy however many PIR only systems falsely detect vacancy conditions while the occupant is still present. Using and audio monitor allows the system to detect human presence by listening specifically for things like key clicks of a mouse, typing and the turning of a page. These elements assist in ensure that the systems do not falsely detect a vacancy condition and then turn the light fixture off while the occupant is present.
Both of these occupancy items utilize the integrated programmable analog blocks included in the PSoC Processor. Specific items utilized include the I2C Slave Bus, A-D, Op Amps, and Current Sources.
The PSoC Process has sufficient processing capabilities to take on the task of performing hundreds of Fast Fourier Transforms (FFTs) as it analyzes the audio monitor while at the same time processing inputs from the PIR and handling requests for status updates from the Host WICED module.
iMatrix WICED Client
The iMatrix WICED Client runs on the WICED Module and is the primary software used to collect sensor data and relay this to the iMatrix Cloud system for real time as well as time series storage. By constantly monitoring the various sensors of the fixture triggers can be used to notify when error/failed conditions are detected. The sampling rates and trigger levels are defined in the product design during the initial definition of the product. These levels can be update for one or all of the fixtures using iMatrix Cloud services. The iMatrix WICED Client provides a secure encrypted TLS/TCP connection to the iMatrix Cloud System.
Light Fixture Software
The Light Fixture is an autonomous system with complex software that has many tasks that simultaneously monitor for changes in the environment to control its operation.
For example, during the manufacturing process the model type of the fixture is programmed into the configuration system on the fixture. The fixture software knows the appropriate power use expected based on the dim level of the fixture. If this dim level falls below what is expected at a certain dim level then the likely issue is a failed driver or LED board. Maintenance personal can be alerted and quickly service the unit.
iMatrix Cloud & Mobile Elements of the System
The full system includes the iMatrix Cloud Application, called Apollo, and a matching Apollo Mobile Application used for control and provisioning.
Using the iMatrix Cloud Application, Apollo, the user initially creates a floor plan of their building and places the fixtures and other items (Switches & other BLE Sensors). The following diagram illustrates a typical installation showing the placement of fixtures on a floor plan.
The Mobile Application is used to provision the fixtures in the field. Fixtures are grouped using a hierarchical structure based on Sites->Buildings->Floors->Rooms->Groups. During the provisioning cycle the fixtures are assigned to their associated groups. This is then used to allow the Mobile application to control the operation and setting of the fixtures either individually or by group.
The following illustration show an example of the mobile Application controlling three different groups of Fixtures.
Using the Cypress WICED Wi Fi and PSoC solution allowed Inventek Systems to create a power IoT Commercial LED Lighting Controller. Coupling this with the iMatrix IoT Cloud platform provides a couple end to end Commercial Lighting Solution. These designs and other IoT Systems are available for licensing from Inventek Systems. For further information please refer to the web site https://inventeksys.imatrix.io/
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