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A project log for Hackable CMWX1ZZABZ (LoRa) Devices

Useful STM32L082-based devices with embedded LoRa radio modem programmable with the Arduino IDE via USB connector, i.e, hackable.

Kris WinerKris Winer 02/25/2018 at 18:522 Comments

02/25/2018

The Sentinel is a purpose-designed utility board for safety and security applications including such things as remote monitoring of the environment, motion detection, and human presence detection, etc. It uses the CMWX1ZZABZ module as host and includes a BMD-350 slave nRF52 for BLE over UART serial bridge. The idea of the BLE slave is to act as a local interface with safety or security personnel via the beacon function as well as back up for the main LoRaWAN communication interface.


The Sentinel is intended to be battery-powered and the 150 mA, 3.3V NCV8170 LDO uses just 500 nA to provide board voltage regulation. The Sentinel has many of the same sensors as the LoRaSensorTile including BME280 pressure/temperature/humidity sensors, BMA280 accelerometer, VEML6040 RGBW ambient light sensor but adds the CaliPile (TPiS 1S 1385) IR presence/motion sensor for human presence detection. The Sentinel also has an 8 MByte SPI flash for holding multiple programs or data logging. All of these components are ultra-low power allowing the Sentinel to sleep with ~10 uA current, wake periodically or when a sensor threshold is crossed (via interrupt), and remain "on-guard" for years on a single AAA battery.

The Sentinel pcb is designed to fit into two off-the-shelf plastic boxes, either a 2.5-inch square box from Bud Industries or a 2.4 x 1.4 inch Hammond box.

The pcb is designed with all components on one side and mounted close to the box face for easy access for the indicator led, ambient light and presence sensors via drilled holes in the box to the outside. The holes can be covered with transparent shields or cellophane tape to provide a barrier to excessive moisture. There is enough room in the boxes for one or more small batteries. In most cases, using a 3.6V booster and a single AAA battery would be sufficient for years of service. The boxes could be mounted using a strong magnet or velcro, etc depending on the application. It is an inexpensive and convenient packaging solution that allows for rapid deployment and change of location to fit the need.

Periodic LoRaWAN transmissions would be used for passing state information and alerting to threshold conditions but BLE, with its greater throughput (~1 kByte/s), could be used for large-scale transfer of data stored on the SPI flash memory. The BLE beacon would be configured to sleep most of the time and wake periodically. Upon detection of a smart device for pairing, such as a smart phone or tablet carried by a security guard or safety inspector, the Sentinel could pair, exchange the proper authorization codes, and upload more extensive stored data to the smart device and download changes in configuration, etc.

Intended deployment would be construction sites, manufacturing and utility complexes, basically anywhere humans are now required to monitor safety and security conditions. Rather than replacing humans, the intent is to augment human eyes and ears with a device that is always "on watch" for conditions out of the ordinary and able to report over long distances that human assistance is required.

Discussions

Kris Winer wrote 02/16/2019 at 23:33 point

It is a design prototype, none have been made for sale.

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Samuel Kramer Schwid wrote 02/16/2019 at 23:28 point

hello, where do I find the board the sentinel to buy?

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