Courtesy of Nordic Semiconductor : Bluetooth Low Energy tire pressure monitoring system
The ‘70mai Tire Pressure Monitoring System’ from 70mai employs Nordic’s nRF51 Series SoC to provide wireless connectivity between the in-car console and the user’s smartphone
Nordic Semiconductor today announces that 70mai, a Shanghai, China-based developer of intelligent car solutions and subsidiary of smartphone giant Xiaomi, has selected Nordic’s Bluetooth® Low Energy (Bluetooth LE) nRF51 Series System-on-Chip (SoC) to provide the Bluetooth LE wireless connectivity for its ’70mai Tire Pressure Monitoring System’. The system provides low latency continuous feedback on a vehicle’s tire pressure, allowing the user to take corrective action in the event of abnormal pressure to avoid potential safety issues.
In operation a pressure sensor is fitted to the tire valve stem on each wheel. The sensor employs a 433MHz wireless transmitter to continuously relay tire pressure data to the dashboard-mounted pressure monitoring console. The console displays the current pressure in each tire, while an alarm alerts the driver in the event tire pressure data is outside the user-specified parameters. The console incorporates Nordic’s nRF51 Series SoC, which provides Bluetooth LE wireless connectivity between the device and the user’s Bluetooth 4.0 (and later) smartphone or tablet. In addition to supervising the wireless connectivity, the Nordic SoC’s Arm® Cortex™ M0 CPU operates as the console’s microcontroller, providing the computing power for all the unit’s functionality. The console is powered by a lithium battery, providing a replacement lifetime of between three and five years.
Once paired, tire pressure data is synced to the user’s mobile, and from the company’s iOS- and Android-compatible ’70mai’ app, the driver can review tire pressure status as well as set alarm parameters. Tire pressure data can also be uploaded to the Cloud from the mobile. The system is also compatible with the company’s ’70mai Smart Rear-view Mirror’, a smart mirror that can be fitted over a car’s existing rearview mirror, providing an eye-level display with navigation functionality, as well as a range of safety warning features including tire pressure from the 70mai Tire Pressure Monitoring System.
Nordic’s nRF51 Series is a family of flexible multiprotocol SoCs ideally suited for Bluetooth LE and 2.4GHz proprietary ultra low power wireless applications. The nRF51 Series SoCs are built around the 32-bit Arm CPU, 2.4GHz multiprotocol radio, 256kB/128kB Flash, and 32kB/16kB RAM. The SoCs are supplied with Nordic’s S130 SoftDevice, a Bluetooth 4.2 qualified concurrent multilink RF protocol software supporting simultaneous Central/Peripheral/Broadcaster/Observer role connections. Nordic’s software architecture includes a clear separation between the RF protocol software and the application code, simplifying development and ensuring the SoftDevice doesn’t become corrupted when developing, compiling, testing, and verifying application code.
“We selected the nRF51 Series SoC for its performance, price, and also because of the Nordic SoftDevice. The software architecture made application development much simpler,” says Hugh Zhu, 70mai Hardware Director.
“Also Nordic’s technical information is very rich, and excellent technical support is available both from Nordic and its distributors. This has been of great help in ensuring the smooth progress of this project,” says Dana Lv, 70mai Tire Pressure Monitoring System product line leader.