Bluetooth LE propane tank level sensor uses ultrasound to provide updates on the amount of fuel in a tank

Mopeka’s Pro Check Sensor employs Nordic’s nRF52810 SoC to calculate and send fuel level data from tank to smartphone app via Bluetooth LE

Nordic Semiconductor today announces that Mopeka, a developer of tank/cylinder management platforms, has selected Nordic’s entry-level nRF52810 Bluetooth® Low Energy (Bluetooth LE) System-on-Chip (SoC) to provide the core processing power and wireless connectivity for its ‘Mopeka Pro Check Sensor’.

The Pro Check Sensor is a propane tank level sensor that mounts magnetically underneath a tank/cylinder—for example, that used for a gas barbecue or in an RV that uses propane for the appliances—and uses ultrasound technology to inform the user how much fuel is left. The sensor uses the integrated Nordic SoC’s 64MHz, 32-bit Arm® Cortex® M4 processor, along with various nRF52810 peripherals (for example, Direct Memory Access (DMA), Programmable Peripheral Interconnect (PPI), and PWM) to measure the time of flight of ultrasound waves in the propane and then use that information to calculate the fuel level of the tank.

The SoC’s peripheral set meets our sensor requirements, with PPI in particular providing a major perk

Jason Peck, Mopeka

Nordic-powered connectivity

Using the Bluetooth LE wireless connectivity provided by the Nordic SoC, the fuel level data is then relayed from the Pro Check Sensor to the Android- and iOS-compatible ‘Mopeka Check’ app on the user’s Bluetooth 4.0 (and later) smartphone or tablet. From the customizable companion app, the user is able to set a threshold alarm so when a tank reaches a low fuel level, a push notification will be sent to inform the user. The fuel level readings can be provided either as a percentage of the tank volume or the height from the bottom of the tank. The app is able to monitor multiple sensors and indicate the battery level, signal strength, quality of the read, temperature, and most recent update time. The user can also connect to Mopeka’s Wi-Fi bridge to read the tank/cylinder information from any location. The app automatically switches to Wi-Fi connectivity when outside Bluetooth LE range, then back to Bluetooth LE when the signal is available.

Fast sampling

The Nordic SoC’s powerful Arm Cortex M4 processor and set of peripherals enabled the Pro Check Sensor to sample four times faster, with higher resolution and for longer intervals than previous products that used a competitor’s Bluetooth SoC. This results in enhanced tank-level sensing performance. In addition, the nRF52810 SoC’s ultra low power consumption extends the Pro Check Sensor’s single CR2032 coin cell battery’s lifetime to an estimated 1.5 years for the default sample rate settings (3.5s updates), or alternatively an estimated battery life of up to four years at lower sample rate settings (for example,10s). The nRF52810 has been engineered to minimize power consumption with a fully-automatic power management system that reduces power consumption by up to 80 percent compared with the nRF51 Series.

Nordic’s nRF52810 multiprotocol SoC combines the Arm Cortex M4 processor with a 2.4GHz multiprotocol radio (supporting Bluetooth 5.2, ANT™, and proprietary 2.4GHz RF protocol software) featuring reduced radio energy consumption, with 192kB Flash memory and 24kB RAM. Nordic's unique software architecture provides clear separation between the RF protocol software and the developer's application code, this simplifies development, and ensures the SoftDevice doesn’t get corrupted when the customer is developing, compiling, testing, and verifying their application code.

“We selected Nordic’s nRF52810 SoC for our Mopeka Pro Check Sensor due to a number of key features and benefits including price, speed, and low power consumption,” says Jason Peck, Partner at Mopeka. “The SoC’s peripheral set meets our sensor requirements, with PPI in particular providing a major perk.

“Having used Nordic’s ‘nRF Connect’ Android app for a number of years, it was a natural next step to also use the company’s chips for our Bluetooth LE devices. Nordic’s open and widely available documentation, part supply, and reference designs were also important factors, while the answers to most questions can be found or quickly provided through Nordic’s active DevZone forum.”

In addition to the Mopeka Pro Check Sensor for measuring propane, the company has developed other devices—namely the Mopeka Water Check Sensor, Mopeka Residential Check Sensor, and Mopeka Bulk Storage Check Sensor—for measuring water or air inside a tank. These sensors also employ Nordic’s nRF52810 SoC.