ST is launching today the STM32WBA6, our first device to allow the concomitant use of Bluetooth and 802.15.2 standards on a single chip, thanks to a bump in memory. Indeed, the new wireless MCU now comes with up to 2 MB of flash memory and 512 KB of RAM. Additionally, this is a dual bank flash, thus enabling live firmware updates for mission-critical systems. The STM32WBA6 also supports a STOP2 mode, which provides even more remarkable power savings thanks to a consumption of only 5 µA (with the real-time clock on), compared to 7.2 µA for STOP1. Often requested by our customers, this new STOP mode provides a new middle ground between runtime and standby.
How is the STM32WBA6 doing more?
New dual bank memory
The bump in a flash and RAM means it’s possible to use the STM32WBA6 as a single chip host MCU for a Matter end node device capable of offering over-the-air updates and a concomitant mode. For instance, that could mean an application that offers Bluetooth and Thread simultaneously. Previously, the STM32WBA5 could work in a Thread border router in a Matter ecosystem. Now, thanks to its 2 MB of Flash, developers can run the wireless stack for end nodes on the STM32WBA6. Consequently, designers can vastly simplify their design and lower their bill of materials, as they no longer require additional external memory.
ST also adopted a dual bank memory, which is unusual for an MCU designed for end-node devices. Traditionally, competing solutions don’t bother with such an intricate architecture. However, ST chose to adopt it because Thread, Zigbee, Matter, Bluetooth, and others are naturally low-bandwidth protocols. It means that downloading the firmware update can take a significant amount of time, and turning off the device during this time could seriously worsen the user experience. Thanks to dual bank memory, users can keep using their device and install the update to one of the memory banks.
New USB High-Speed controller
The STM32WBA6 is the first STM32WB to come with a USB High Speed (USB 2.0) controller, which is essential to help fill up the extra memory faster when flashing firmware, among other things. Too often, makers overlook the USB controller. The MCU mainly targets end devices, like those in home automation, which means final users primarily interact through a smartphone app and use a battery. Most of the time, only developers or engineers in industrial settings use the USB interface for flashing operations, maintenance, or log analysis. However, moving to USB HS significantly improves the quality of life of the few who use it, which explains why we sought to add it to our new wireless MCU.
New design possibilities
Finally, the STM32WBA6 brings an improved radio IP, pin-to-pin compatibility with the STM32WBA5, numerous packages (WLCSP88, QFN48, QFN68, BGA121), and up to 86 GPIOs, which is helpful when creating a feature-rich application with sensors or an NFC reader. Not only were we able to come up with a device with more RAM, but we are leveraging a reliable radio that offers +10 dBm output power, -100.5 dBm of RX sensitivity in Bluetooth LE at 1 Mbps, packages ranging from 0.35 mm in thickness to 0.5 mm, and more pins than what is traditionally available. While others may offer a similar radio, very few can match our packaging diversity and programming flexibility.
How is the STM32WBA6 keeping power consumption in check
New STOP2 mode
The STM32WBA6 is also unique because it brings a STOP2 low-power mode absent on the STM32WBA5. The reason we can offer such a mode is due to our manufacturing improvements. Few realize that every STOP mode requires dedicated logic and other components that take up space on the die. A bigger die can be harder to cool, more expensive, and subject to lower yields, making the whole device more expensive. The STM32WBA6 not only adds a new STOP mode but doubles the memory found on the STM32WBA5. Consequently, the die is bigger, but being an integrated device manufacturer with fabs worldwide, ST was able to solve the inherent challenges of a larger die.
Similarly, we worked with other ST divisions to develop a 50Ω in/out external front-end power amplifier for all STM32WBA devices. We will officially release it at the end of the year, enabling our customers to reach up to +20 dBm in output power with a small form factor part. The front-end integrates harmonic filtering together with an RF switch, providing seamless support for antenna diversity and AoA/AoD use cases. Traditionally, competing solutions tend to integrate such a device in a system-on-chip. The problem is that it seriously increases overall power consumption. By using this external device, designers can easily improve their radio performance while keeping their power consumption in check.
