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The SPWF04SA and the SPWF04SC are ready-to-use Wi-Fi modules conceived for Internet of Things (IoT) applications. The modules integrate a Cortex-M4-based STM32 microcontroller and a powerful Wi-Fi transceiver, compliant with IEEE 802.11 b/g/n standard for the 2.4 GHz band.

The modules are cloud compatible thanks to the complete protocol package, which includes application and security layers. They can operate in serial-to-Wi-Fi and standalone mode, with customer applications developed in the subsystem based on the MicroPython environment. With low power consumption and an ultra-compact (2.7 x 1.5 cm) footprint, the modules are ideal for fixed and mobile wireless applications, as well as challenging battery-operated applications.






SPWF04S HW Architecture



  • Smart appliances
  • Industrial control and data acquisition
  • Home automation and security systems
  • Wireless sensors
  • Cable replacement
  • Medical equipment
  • Machine-to-machine communication



  • 2.4 GHz IEEE 802.11 b/g/n transceiver
  • High performance STM32F439
    • ARM® Cortex®-M4
    • 256 KB SRAM
    • 2 MB embedded high-speed Flash memory
    • 1 MB Flash memory for user storage, extendable via SD/MMC interface or external SPI Flash
  • Integrated TCP/IP protocol stack
    • 8 simultaneous TCP or UDP clients and 2 socket servers (supporting up to 8 clients each)
    • Secured socket and upper layers (i.e. HTTPS) supporting up to TLS 1.2, including AES (128, 256), hash (MD5, SHA-1, SHA-256) and RSA (1024, 2048)
    • Web server supporting SSI
  • Open, WEP, WPA2 PSK, WPA2 Enterprise
  • WPS for station
  • System modes: Station, IBSS, and miniAP (supporting up to 5 Stations)
  • miniAP easily provisioned (SSID, PWD)
  • Fast Wi-Fi re-association after reset
  • Secure Firmware and FileSystem updates Over The Air (OTA)
  • TX power
    • 18.3 dBm @ 1 Mbps DSSS
    • 13.7 dBm @ 54 Mbps OFDM
  • RX sensitivity
    • -96.0 dBm @ 1 Mbps DSSS
    • -74.5 dBm @ 54 Mbps OFDM
  • 19 configurable GPIOs available
  • UART and SPI interface to host system
  • Advanced low-power modes
    • RX traffic 105 mA typical
    • TX traffic 260 mA typical @ 10 dBm
  • AT command set interface through UART
  • SPI interface with simple protocol
  • Application subsystem
    • Embedded real-time MicroPython environment for customer applications and on-board development
    • MicroPython API library for easy access to Wi-Fi subsystem capabilities and device peripherals (i.e. UART, SPI, I²C)
  • Small form factor: 26.92 x 15.24 x 2.35 mm
  • Single voltage supply (3.3 V typical)
  • Antenna options: integrated antenna/U.FL connector
  • Industrial temperature range: -40°C to 85°C
  • FCC/CE/IC certified
  • RoHS compliant



  • The modules are cloud compatible thanks to the complete protocol package, which includes application and security layers.
  • Supports WPA2-Personal and WPA2-Enterprise security and WPS (Wi-Fi protected setup)
  • For secure end-to-end communication with the cloud, an SSL/TLS stack is embedded in every module, with no licensing charge.
  • Multiple higher level protocols over TCP are supported by the module including: HTTP, MQTT, SMTP, and WebSockets
  • Multiple protocols supported over UDP include: TFTP, SNTP and mDNS; the module also includes IPv6 networking capabilities
  • Includes a MicroPython scripting engine to enable simple and fast custom application development on the module MCU: no external MCU is needed and the customer application runs directly on the module



Order Code Description Production Status
SPWF04SA Integrated Antenna Q2-2017
SPWF04SC Integrated U.Fl. connector Q2-2017


Evaluation Boards

Order Code Description
X-NUCLEO-IDW04A1 Wi-Fi evaluation board based on SPWF04SA module, to allow expansion of the STM32 Nucleo boards; usable also with STEVAL-PCC018V1 Available now in sample and in production from April 2017


SW and Documentation

Order Code Description
STSW-WIFI004 SW Package containing .bin and .ota files




X-NUCLEO-IDW04A1 Eval Board


The X-NUCLEO-IDW04A1 Wi-Fi evaluation board is based on the SPWF04SA module Equipped with the Arduino UNO R3 and ST Morpho connector, this evaluation board is designed to be plugged directly on the STM32 Nucleo board and can be cascaded with multiple boards to develop a larger ecosystem. The X-NUCLEO-IDW04A1 interfaces with the MCU on the STM32 Nucleo board via the UART serial port and SPI interface. Wi-Fi application development is made easy through the example code via the free development firmware library.