While working for MapLarge, we started investigating wireless SoC's that could provide the lowest possible power consumption. I found Nordic Semiconductor SoC's to be the best choice because of their ability to draw extremely low amounts of power in sleep, there are ample amounts of documentation, SDK examples and user examples out on the open web, and the parts have also been somewhat adopted by the open source communities. We built a variety of products with Bluetooth Low Energy, LTE-M, GPS and LoRa radios. We also spent considerable time learning and using Zephyr RTOS to obtain low power. Below are some of my favorite boards that I made for Nordic chips.

This Bluetooth Beacon was the simplest device we made, as it had only one SoC. The goal was to make a small device for basic sensor readings using BLE beacons, powered with a coin cell battery maximum battery life. At this point I have had several of these devices running since Oct 2021, so they have over 2 years of battery life. It's sleep current draw is 5 uA @ 3.0 V.

• Laird BL654 module for nRF52840 BLE SoC (the module allows for a much smaller footprint)
• CR2032 replaceable battery
• Sensirion SHTC3 temperature and humidity sensor
• Crocus CT8132SK Tunnel Magneto-resistance (TMR) digital magnetic sensor
• LIS2DW12 accelerometer
• Push button (hold to enter config mode)
• RGB LED
• Waterproof case for mounting or keychain connection

The LTE asset tracker as a much larger device that combined multiple radios into this IoT device. The main application ran on the nRF9160 LTE SoC, while the nRF52840 allowed for BLE connectivity to apps in addition to scanning for other BLE beacons to retrieve sensor data. There was also a Microchip WLR089U0 LoRa module for sending additional data over LoRa. This tracking device ran on either a rechargeable battery or 6 AA batteries for over a year of battery life. Its sleep current draw is < 100 uA @ 5V.

• nRF9160 LTE+GPS SoC
• LTE-M operation for main data reporting
• Laird BL654 module for nRF52840 BLE SoC
• Same SHTC3, LIS2DW12, and CT8132SK sensors as above
• TSL25721 light sensor, BME280 temperature, humidity and pressure sensor
• uBlox ZOE-M8Q for superior GPS performance as well as simultaneous LTE + GPS operation
• Custom flexible NFC antenna for easy BLE pairing
• nanoSIM slot
• microSD slot
• Onboard flash memory

We had a proposal for a project that involved both BLE and LoRa, but it required some kind of display and no need for LTE. So, I designed another board that had only the nRF52840 and WLR089U0 and added an e-ink screen. This monochromatic screen only draws power (about 10mA) while it is updating the screen. This is the perfect screen for a device that only needs to occasionally update the screen. Unfortunately this project never made it off the ground so all I have is this prototype board. Maybe I will find another use for it some day.

• Laird BL654 module for nRF52840 BLE SoC
• Same SHTC3, LIS2DW12, CT8132SK, TSL25721, and BME280 sensors as above
• 1.54“ E-ink screen (AES200200A00-1.54ENRS)
• Waterproof USB-C connector for charging and data transfer
• Rechargeable 400 mAH Li-po battery
• RGB LEDs
• 4 pushbuttons for menu navigation