Bluetooth 5.2 garage door monitoring system provides open and close alerts

Two Commas’ Garage Door Minder uses Nordic’s nRF52811 and nRF52820 SoCs for wireless connectivity between transmitter and meshed receivers

Nordic Semiconductor today announces that West Sacramento, CA-based engineering and design firm, The Two Commas Company, has selected Nordic’s nRF52811 Bluetooth® 5.2/Bluetooth Low Energy (Bluetooth LE) System-on-Chip (SoC) and nRF52820 Bluetooth LE multiprotocol SoC for its patented ‘Garage Door Minder® (Version 2)’. The home security solution is simple to install, does not require the support of a home Wi-Fi network, and represents the first Bluetooth LE wireless garage door monitoring system of its kind, according to the company.

Garage Door Minder comprises a transmitter device using the nRF52811 SoC which attaches to a garage door and features a tilt switch sensor to alert of the door opening, as well as a USB receiver (with optional wall plug adaptor) integrating the nRF52820 SoC. When notified by the transmitter that a door has been opened, the receiver will generate audible (beeper) and visual (LED flash) alerts until the door is closed, acting as a useful reminder to householders to close their garage door, or acting as notification in the event the garage door has been opened without their knowledge.

Nordic’s support through the supply chain and development processes has gone above and beyond our expectations

Robert Lawson, The Two Commas Company

Bluetooth mesh network

According to the company, the transmitter and receiver can communicate wirelessly over an indoor range of approximately 30 meters (100 feet) and an outdoor range of approximately 180 meters (600 feet) using the Bluetooth LE connectivity provided by the Nordic SoCs. In addition, multiple receivers can be connected with the push of a button via a nRF52820 SoC-enabled Bluetooth mesh network to extend the operating range even further. Nordic’s nRF52820 SoC supports Bluetooth 5.2’s high throughput (2Mbps) and Long Range functionality, as well as Bluetooth mesh which is ideal for home automation applications. Full Speed (12Mbps) USB operation is a key feature of the nRF52820. USB is a popular connectivity interface that enables low-latency and high-bandwidth communication with a range of host devices.

Users of the Garage Door Minder can also use their Bluetooth 4.0 (and later) smartphone as a receiver, from which the associated iOS/Android ‘Door Minder’ app can provide vibration/beeper alerts when the garage door is open, as well as sleep button functionality to delay notifications. The Garage Door Minder transmitter uses two ER14250 half AA lithium batteries to achieve a minimum battery life of 2-3 years based on a total transmit mode of around 15 minutes per day, thanks in part to the low power characteristics of the Nordic nRF52811 SoC.

Fully-featured connectivity solution

Nordic’s nRF52811 multiprotocol SoC is a fully-featured connectivity solution that supports Bluetooth 5.1 Direction Finding, which brings precise positioning capability to the SoC in addition to all the features of Bluetooth 5. The nRF52811 combines a 64MHz, 32-bit Arm® Cortex® M4 processor, with a 2.4GHz multiprotocol radio (supporting Bluetooth 5.2, Bluetooth Direction Finding, Thread, Zigbee, IEEE 802.15.4, and proprietary 2.4GHz RF protocol software) featuring 4dBm output power with -97dBm sensitivity (at 1Mbps in Bluetooth 5 mode), and 192kB Flash memory plus 24kB RAM.

Nordic’s nRF52820 SoC brings a lower end option with built-in USB and a fully featured multiprotocol radio. The nRF52820 combines a 64MHz 32-bit Arm Cortex-M4 processor with 2.4GHz multiprotocol radio (supporting Bluetooth 5.2, Bluetooth Direction Finding, Long Range, Bluetooth mesh, Thread, Zigbee, IEEE 802.15.4, and proprietary 2.4GHz RF protocol software) and 256kB Flash memory plus 32kB RAM. The SoC’s 2.4GHz radio features 8dBm TX power and -95dBm sensitivity (at 1Mbps in Bluetooth LE mode) for a link budget of +103 dBm. The SoC features 12Mbps Full Speed USB device and extended temperature range of -40 to 105°C.

The nRF52820 includes up to 18 GPIOs and a range of analog and digital interfaces such an analog comparator, SPI, UART, TWI, and QDEC. When connected to a USB host, the nRF52820 can be directly powered by the always-present 5V VBUS signal. Nordic provides a reference layout for this configuration.

The nRF Connect SDK [Software Development Kit] is recommended for nRF52811 and nRF52820 software development. The nRF Connect SDK integrates the Zephyr RTOS, supports applications using Bluetooth LE, Bluetooth mesh and Thread, and includes examples, Bluetooth LE profiles and driver support for all peripherals.

“We selected Nordic solutions for Garage Door Minder due to a number of benefits including long range capability, low power consumption, and Nordic’s commitment to superior product support,” says Robert Lawson, Company Founder and Product Inventor, The Two Commas Company. “Nordic’s support through the supply chain and development processes has gone above and beyond our expectations.”