STM32WL – a new microcontroller with integrated LoRa long range radio system

 

The STM32WL system expands the portfolio of STMicroelectronics microcontrollers equipped with a radio system (STM32W family). Made in SOC technology, STM32WL integrates the LoRa standard with efficient uC with the Cortex M4 core. This system is a pioneer of the STM32 family in the field of wireless communication in the band below GHz (sub-GHz), offering easy using and reliability. It is perfectly adapted to a wide range of industrial and consumer applications worldwide.

The growing market demand for long-range narrowband communication underlies the creation of the STM32WL system. According to the idea of the STM32W family, it combines uC and a radio system. In this case LoRa technology was implemented.
STM32WL
The uC used is based on the well-known Arm® Cortex®-M4 core, and the radio system is based on the IP core SX126x. The system can work not only in the LoRa® standard, it also provides many standard modulations (G) FSK, (G) MSK, BPSK. Thanks to this, it flexibly fits into wireless applications with LoRaWAN® or with different protocol in a completely open way, e.g. for the needs of IoT. The built-in LoRaWAN® stack is available as an option.

STM32WL was developed with use of the same technology as that in STM32L4 microcontrollers. Thanks to this, STM32WL on the one hand contains a similar set of digital and analog peripherals and on the other is characterized by very low power consumption providing long battery life.

To ensure worldwide compatibility, the STM32WL MCUs are equipped with two RF power amplifiers (15dBm and 22dBm) and a wide linear frequency range to match any needs in the unlicensed RF band.

STM32WL

Wireless connection worldwide

STM32WLE5 microcontrollers comply with the requirements for the physical layer of the LoRaWAN® specification issued by LoRa Alliance®. Available LoRa®, (G) FSK, (G) MSK and BPSK modulations can also be used in older and proprietary protocols.

The radio is suitable for systems that comply with radio regulations, including but not limited to ETSI EN 300 220, FCC CFR 47 Part 15, Chinese regulatory requirements and Japanese ARIB T-108. The continuous frequency range from 150 to 960 MHz supports all major ISM sub-GHz bands worldwide.

 

STM32WL

 

System peripherals

The STM32WLE5 line covers a wide range of communication functions, including up to 43 GPIO, integrated SMPS to optimize energy consumption, many low power modes to maximize battery life.

Security and ID

In addition to the wireless functions and very low power consumption, STM32WL microcontrollers include built-in hardware functions such as 128- / 256-bit AES hardware encryption, PCROP read / write protection and public key cryptography with an elliptic curve encryption engine.

 

STM32WL

 

Where to use the STM32WL microcontroller? STM32WL fits perfectly as part of many LPWAN-based applications:

  1. Smart cities & buildings
    • Up to +22 dBm output power for wide
    • -148 dBm sensitivity with LoRA: robust RF link
    • Reduced BOM cost
  2. Logistics
    • Unique IDs for enhanced traceability
    • Down to 390 nA mode with RTC and 32KBof RAM for extended battery lifetime
    • Small form factor with UFBGA 5×5 packages
  3. Industrial IoT
    • Up to 105C deg. MCU capable
    • Only 5 µs wakeup time for best latencies
    • Only 5.4mA as LoRa RX consumption for battery optimization
  4. Smart agriculture
    • Link budget >160 dB = very long ranges
    • Excellent battery lifetime: only 15 mA for LoRa TX consumption @ 10dBm
    • PCROP, ECC, TRNG, PKA for best design robustness
  5. Smart home
    • Down to 71 µA/MHz in run mode for efficient action
    • 12-bit ADC &DAC for mixed applicative use cases
  6. Utilities
    • Worldwide compatibility 150 MHz to 960 MHz linear range
    • Multi-protocol cable
    • ST longetivity commitment: 10 year life time

Antennas – it’s good to use proven products
STM32WL
Matching the right antenna to your wireless application is always a challenge for the designer. When creating an application based on the S2-LPTX transmitter, it is worth considering the use of antennas from Proant or Unictron. In particular, we recommend the Pro-OB-471 model from Proant (PIFA type antenna for the frequency range: 860MHz – 870MHz, 902MHz – 928MHz) and model AA701 from Unictron (ceramic antenna for the operating frequency range: 863 – 870 Mhz). The Unictron PRO-OB-471 antenna shows very low sensitivity of radio parameters to metal elements located in close proximity to the antenna.

Recommended quartz and TCXO

For the application based on the S2-LPTX system, we propose small quartz for surface mounting, which are dedicated to this solution. The NDK product called NX3225GA has compact dimensions (3.2 × 2.5 × 0.75 mm) and high frequency stability. For applications that require a narrow radio channel and work in a wide temperature range, we recommend TCXO NT2016SA from NDK.

 

STM32WL
Apply STM32WL module in your application – evaluation board Masters

In cooperation with STMicroelectronics, Masters designed an evaluation board based on the STM32WL module. Please contact our R&D department rd@masters.com.pl to receive the evaluation board, samples and additional technical support.