These IoT-oriented MCUs are suitable for smart metering (water, gas, electricity), alarm systems, smart building devices, logistics tracking, and proximity sensing. They are also ideal for advanced monitoring systems, such as smart city monitoring, smart agriculture (including soil condition and livestock welfare reporting), forest fire detection, water metering, and leakage detection.
Developers working on new products can leverage flexible product options, ultra-low-power architecture, best-in-class RF efficiency, and innovative features to optimize wireless communication range, streamline product design, and maximize battery life.
The new MCUs integrate ST's unique analog flow sensing controller (LCSC), simplifying and optimizing water meter designs. The LCSC circuitry works with traditional electromechanical water meters to measure flow without MCU intervention and offers tamper protection. These features enhance water meter security, extend battery life to over 15 years, and optimize integration and cost structures.
Additionally, the series includes an ultra-low-power (4.2 µA) wideband wake-up RF receiver. While the main communication RF transceiver is powered down to save energy, this receiver listens for wake-up signals with negligible battery impact. It responds quickly upon receiving the correct RF wake-up signal, enabling applications like mobile meter reading or firmware updates for battery-powered monitoring devices. Wake-up signals from fixed position beacon tags can also transmit information via OOK modulation, providing convenient asset tracking or location marking solutions for logistics and warehousing.
The chip integrates a full suite of programmable memory, peripherals, and security services, enabling developers to create feature-rich applications with minimal external circuitry. Features include 256 KB flash memory, 32 KB SRAM, flexible peripherals such as a 16-segment LCD driver, 12-bit 1Msample/s ADC, analog comparators, DAC, multiple timers, and RTC. Security services include secure boot, secure firmware updates, 128-bit AES, and RNG.
The series supports 413–479 MHz or 826–958 MHz license-free bands, with a special model, STM32WL33CCV6A, designed for 169 MHz communication. The STM32WL33 integrates dual programmable power amplifiers with RF output power options of +14 dBm and +20 dBm, further optimizing efficiency during active transmission. To save energy, regulations in the EU, South Korea, and Japan limit RF output power to +14 dBm. In North America and APAC, the +20 dBm option allows extended communication range. This flexibility enables global deployment and roaming for tracking applications.
The highly configurable RF transceiver supports multi-protocol operation and flexible modulation schemes, including 4-(G)FSK, 2-(G)FSK, (G)MSK, DBPSK, DSSS, and ASK, with data rates up to 600 kbit/s. A programmable autonomous state machine (Radio Sequencer) automates standard RF operations, such as frequency hopping, low-duty-cycle operations, LBT, RX Sniff, and auto-acknowledgment, reducing MCU intervention and improving RF efficiency.
RF receiver sensitivity of -132 dBm @300 bit/s 433 MHz OOK and -128 dBm @300 bit/s 868 MHz 2-(G)FSK ensures stable, reliable long-range communication. At +20 dBm output power and -128 dBm sensitivity (868 MHz), the link budget supports wireless communication distances exceeding 1 km at 300 bps GFSK.
The MCU features an IQ interface for custom modulation schemes, enhancing reception sensitivity. Developers can use tools like GNURadio for performance testing before embedding optimized protocol stacks. Standard protocols supported include wM-Bus, Mioty, Wize, Sigfox, 6LowPAN, and Wi-SUN Home Area Network (HAN).
As a wireless system-on-chip (SoC), the STM32WL33 series seamlessly integrates with ST’s MEMS inertial and environmental sensors, leveraging ST's ML/AI algorithms and tools to develop applications requiring location and situational awareness, as well as battery-powered remote monitors and wireless sensors for industrial, smart city, or agricultural use cases.
The STM32WL33 series connects developers to the extensive STM32 ecosystem, now including STM32CubeWL3 software, middleware, NUCLEO-WL33CC1 (868–915 MHz), and NUCLEO-WL33CC2 (433 MHz) development boards. The series also offers dedicated matched filters (MLPF-WL-01D3/02D3/04D3) using ST’s integrated passive device (IPD) technology for space-saving RF performance optimization. Additionally, free reference designs (STDES-WL3xxxx) reduce development costs and simplify RF design, covering frequency bands, RF power, MCU packages, and PCB layers. These designs are pre-certified and fine-tuned for specific use cases.
The Wireless Studio Environment (STM32CubeWiSE) offers a graphical user interface for accelerated learning and out-of-the-box experiences. The toolbox includes the WiSE-RadioCodeGen RF protocol automation code generator and WiSE-RadioExplorer browser. The generator features the new WL33 Radio Sequencer, while the browser helps users optimize RF features and complete RF certification processes efficiently.
The STM32WL33K8V6 in QFN32 packaging is now available. NUCLEO-WL33CC1 and NUCLEO-WL33CC2 development boards are also available on the ST eStore and through authorized distributors.