Jarrod Krebs
Collecting data from the surrounding environment can be beneficial if you want to understand changes in environmental factors caused by building-automation algorithms and gather more sensor data relating to the security of the structure. One problem with adding more sensors to a building is the vast amount of cabling required to power and communicate with these devices. Internet of Things (IoT) devices with wireless sensors alleviate cabling issues, and I wrote about resolving battery-life problems in my previous blog post, “Increasing battery life in IoT devices.” But some applications are still wired, including two that I want to tackle today: ambient light sensors and door and window sensors. There are ways to make these traditionally wired applications wireless, and it’s not as cumbersome as you might think!
When used in commercial buildings, ambient light sensors detect the intensity of light in a given area and balance the overall ambient light in a given work space. Light sensors are usually wired to the lights they control. A wireless solution can be created by connecting the lights to a smart controller with wireless connectivity and installing a wireless light sensor near a window. The wireless sensing node would also make retro fitting the system easier.
If the sunlight coming through the window is not enough to light the work area, but the lights in the room are not adjustable, then the room could be too bright. Let's say that 60% of the light enters the room through skylights and windows. A wireless ambient light sensor platform can sense the intensity of that light and dynamically adjust the artificial light source to produce the other 40%. Since the artificial light source isn’t running at full power when natural light is also present, the building will consume less energy (Figure 1).
If wireless ambient light sensing seems interesting, see TI’s Energy Harvesting Ambient Light and Environment Sensor Node for Sub-1GHz Networks Reference Design.
Door and window sensors will also soon become wireless. Many industrial and building-automation security systems use sensors to monitor the opening and closing of doors and windows. In a security system, a central monitoring device generates notifications and alarms based on information from multiple door and window sensors. That creates a lot of wiring that needs installation. Plus, switching all door and window sensors to battery power makes the maintenance cost of changing batteries prohibitive.
Door and window sensor applications typically use magnets to determine when a door or window opens or closes. In a typical configuration the magnet is embedded in the door or window and the sensor is attached to the door or window frame. The sensor and magnet are placed such that they are in close proximity when the door or window is closed, and away from each other when the window or door is opened. Because these sensors are used primarily in security applications, tampering detection is required. Some configurations use multiple sensors to detect magnet tampering.
To enable long battery life, TI’s Low-Power Door and Window Sensor with Sub-1GHz and 10-Year Coin Cell Battery Life Reference Design uses two ultra-low-power digital Hall effect sensors, as shown in Figure 2.
Enabled by the ultra-low-power digital Hall effect sensors and SimpleLink™ wireless microcontroller (MCU) platform, this reference design demonstrates a door and window sensor solution that requires no wiring, while also fully maximizing battery life.
Battery life will be a key concern as more building-automation applications turn to wireless sensor nodes. Ultra-low-power sensors, op-amps, and wireless microcontrollers from Texas Instruments can help lower average current in your battery powered applications.
TI PROVIDES TECHNICAL AND RELIABILITY DATA (INCLUDING DATASHEETS), DESIGN RESOURCES (INCLUDING REFERENCE DESIGNS), APPLICATION OR OTHER DESIGN ADVICE, WEB TOOLS, SAFETY INFORMATION, AND OTHER RESOURCES “AS IS” AND WITH ALL FAULTS, AND DISCLAIMS ALL WARRANTIES, EXPRESS AND IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT OF THIRD PARTY INTELLECTUAL PROPERTY RIGHTS.
These resources are intended for skilled developers designing with TI products. You are solely responsible for (1) selecting the appropriate TI products for your application, (2) designing, validating and testing your application, and (3) ensuring your application meets applicable standards, and any other safety, security, or other requirements. These resources are subject to change without notice. TI grants you permission to use these resources only for development of an application that uses the TI products described in the resource. Other reproduction and display of these resources is prohibited. No license is granted to any other TI intellectual property right or to any third party intellectual property right. TI disclaims responsibility for, and you will fully indemnify TI and its representatives against, any claims, damages, costs, losses, and liabilities arising out of your use of these resources.
TI’s products are provided subject to TI’s Terms of Sale (www.ti.com/legal/termsofsale.html) or other applicable terms available either on ti.com or provided in conjunction with such TI products. TI’s provision of these resources does not expand or otherwise alter TI’s applicable warranties or warranty disclaimers for TI products.
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright © 2023, Texas Instruments Incorporated