Cloud-compatible Wi-Fi Module secures IoT and M2M comms

March 08, 2017 // By Graham Prophet
This cloud-compatible Wi-Fi module from STMicroelectronics, for IoT and M2M devices, provides advanced Internet-security and application protocols, and hosts a microcontroller capable of supporting operation in standalone or serial-to-Wi-Fi modes.

The SPWF04 Wi-Fi module integrates an ARM Cortex-M4 STM32 microcontroller with a set of multi-functional GPIOs and with 2 MB on-chip Flash and 256 kbyte RAM for code and data storage. Features include a hardware cryptographic accelerator and an SPI port for faster host communications. Its MicroPython scripting engine simplifies development of custom applications to run directly on the module in standalone mode. Host interactions can use AT commands via a UART, compatible with the previous generation of Wi-Fi modules, or equivalent proprietary protocol over SPI.


Support for strong internet-security protocols includes WPA2-Enterprise, which enables enhanced authentication and access control in large networks, and Wireless Protected Setup (WPS) that helps safely connect devices like printers or embedded systems. There is also support for advanced HTTPS and encryption protocols including Transport Layer Security (TLS), as well as Secured Over-The-Air (OTA) updates for applying software, firmware, or Flash file-system upgrades in the field via the Wi-Fi connection.


A full-featured TCP/IP protocol stack including HTTP, HTTPS, MQTT, SMTP, and WebSockets, simplifies connections to the Cloud and mobile devices such as smartphones or tablets. Multiple UDP* protocols, including TFTP, SNTP, and mDNS, aid device discovery and file exchanges. Further highlights include IPv6 support, extended web-server functionality (SSI) to simplify interaction with connected devices, and a REST (REpresentational State Transfer) API that enables bandwidth-efficient interaction with web resources.


Versatile operating modes simplify integration with existing network infrastructure, using the module in Station mode, or setting up direct point-to-point connections using the module in MiniAP mode as an access point for other devices (up to five stations). The SPWF04 also comes with an extensive socket layer, capable of managing up to eight socket clients or two socket servers simultaneously handling up to eight clients each, or two WebSocket clients.


The SPWF04 has high RF output power and receiver sensitivity, ensuring reliable communication even in harsh environments. It measures 26.92 x 15.24 x