Single-chip Bluetooth low energy (BLE) solutions are continuously pushing the envelope in terms of shrinking footprint area and lowering power usage in order to meet the design requirements for wearable and other space-constrained Internet of Things (IoT) applications.
The BLE short-range wireless technology—also known as Bluetooth Smart or Version 4.0+ of the Bluetooth specification—has originally been designed for energy-constrained sensors and connected devices. So the diversity of the IoT realm is constantly driving chipmakers toward toying with power, size, and cost premises.
Take the case of Nordic Semiconductor’s nRF52832 system-on-chip (SoC) for BLE applications, launched in summer 2015. The chipmaker has been aiming this SoC for wearable devices, smart home, toys, and wireless charging.
Nordic’s nRF52832 chipset powers the Arduino Primo baseboard for IoT applications. Image courtesy of Nordic Semiconductor.
The nRF52832 chipset boasted a 64MHz ARM® Cortex®-M4F processor to raise the performance bar, facilitate protocol and application tasks in shorter time frames, and enable power-saving modes more quickly.
Nordic’s BLE chip also featured 512kB flash and 64kB RAM; the firm increased the RAM size to explore new BLE features like IPv6 support. Likewise, more on-chip flash would better facilitate data storage as well as application code. Apart from connectivity features and software stacks, more memory allows more simultaneous Bluetooth connections.
Then, there was a multi-protocol radio transceiver that included BLE, ANT/ANT+, and 2.4 GHz proprietary radio with a receive sensitivity of -96dB and a peak transmit current of 5.5mA and an on-chip RF Balun for antenna matching.
Another prominent feature was the on-chip NFC™ tag for simplifying the process of authenticated pairing between two Bluetooth-enabled devices. This BLE chipset packed all this functionality in a 6.0 by 6.0mm QFN48 package.
Fast forward to July 2016. Nordic has announced the availability of nRF52832’s wafer level chip scale package (WL-CSP) version, which offers the same feature set and comes in a more compact 3.0 by 3.2mm footprint. The quad flat no-leads (QFN) package is larger while the WL-CSP package—the silicon die with solder balls—is smaller and consumes less material.
Here, it’s worth remembering that the WL-CSP is smaller than the QFN package and is thus more suitable for wearable and space-constrained IoT designs. However, it requires greater care on the PCB design because of the need for tighter tolerances.
The smaller WL-CSP version of the nRF52832 chipset offers the same features as its QFN counterpart. Image courtesy of Nordic Semiconductor.
Nordic managers claim it’s the smallest BLE chipset available in the market for lighter and slimmer IoT form factors. It boasts a fully automatic power management system and a range of analog and digital interfaces for connecting to a wide array of components such as sensors, displays, touch controllers, LEDs, keypads, motors, and digital microphones.
Moreover, it supports Nordic’s Bluetooth 4.2 stacks and related software development kits (SDKs), including S132 software stack, nRF5 SDK, nRF5 SDK for HomeKit, and nRF5 SDK for AirFuel resonant wireless charging. Nordic also provides protocol stacks for BLE, ANT and Gazell (2.4 GHz) as software downloads.