$6 RAK3172 WisDuo LoRaWAN module features STMicro STM32WL LoRa SoC

RAK3172 WisDuo is a LoRaWAN module smaller than most coins with 15.5×15 mm dimensions made possible thanks to STMicro STM32WL Cortex-M4 LoRa SoC, which we previously found in Seeed Studio’s $10 LoRa-E5 module and corresponding development boards.

But while Seeed Studio relies on STM32WLE5JC SoC with 256KB flash and 64KB RAM in a 73-pin UFBGA package, RAKwireless RAK3172 Wisduo is powered by STM32WLE5CC with the same amount of memory or storage, but in a  48-pin UFQFPN package, and an even lower price at just $5.99 in single units.

RAK3172 WisDuo

RAK3172 Wisduo specifications:

  • SoC – STMicro STM32WLE5CC55 Arm Cortex‐M4 MCU @ 48 MHz with 256 KB flash memory with ECC, 64 KB RAM, and a sub-GHz radio based on Semtech SX126x
  • LoRaWAN 1.0.3 specification compliant
  • Supported bands – EU433, CN470, IN865, EU868, AU915, US915, KR920, RU864, and AS923
  • LoRaWAN Activation by OTAA/ABP
  • LoRa Point to Point (P2P) communication
  • Range – Greater than 15 km with optimized antenna
  • Host interface – UART with AT Command Set via UART interface
  • Other I/Os – SPI, I2C, ADC, GPIO
  • Supply Voltage – 2.0 V ~ 3.6 V
  • Dimensions – 15.5 x 15 mm
  • Power Consumption – 1.69 μA in sleep mode
  • Temperature Range – -40°C to 85°C
rak3172 block diagram
Block Diagram
rak3172 pinout diagram
Pinout diagram

The module can connect to various LoRaWAN server platforms like TheThingsNetwork (TTN), Chirpstack, Actility, etc…, and also supports LoRa Point to Point (P2P) communication mode so a gateway may not even be needed.

You’ll find documentation and firmware files for the module on RAKwireless documentation website. I also noticed ARMbed repository on Github with the code to run Arm mbed OS on the two STM32WL modules we’ve discussed in this post.

RAK3172 Wisduo module can be purchased on RAK’s one shop for $5.99 plus shipping. There’s also the RAK3272S breakout board which will allow you to more easily access the I/O of the module sold for $15.

rak3172 breakout boardI remember when we started to write about LPWAN technology several years ago, the long-term goal was to get $2 LPWAN modules, and we’re not there yet albeit close with some 868/915MHz modules going for under $4, but considering WiFi IoT modules can be had for that price, I don’t see why eventually LoRa, Sigfox, and/or other LPWAN modules could not eventually become just as cheap.

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9 Replies to “$6 RAK3172 WisDuo LoRaWAN module features STMicro STM32WL LoRa SoC”

  1. Proprietary radio standards…
    Unfortunately there’s nothing similar to Bluetooth or WLAN competing with lora, else prices would be on a level of an esp module

  2. Anyone have any experience applying LORA indoors — for example between floors in a multi-story steel and concrete building with low data rate? I would expect the range to be better than WiFi but still rather limited.

    1. Yes, the range is better than WiFi. WiFi operates on 2.4 and 5Ghz. So, no wonder it has a hard time within buildings. Lora operates on < 1 Ghz. (The frequency depends on your region)
      But you can also just use good old 433 Mhz. There are cheap ICs out there who operate on 433 Mhz. The CC1101 is a good candiate. We have a 6LoWPANish stack for it in RIOT. So, you can even operate IPv6 on it.

    2. LoRa can’t be used like Wi-Fi or Bluetooth. You can’t transmit for more than 30 seconds at the most in any TTN region and in Europe you technically have much stricter limits.
      You also have a radio that isn’t capable of sending nearly as much data as Bluetooth can.
      There’s a good tool in the link that allows you to calculate how much data you can send depending on the frequency and region.

      If you want something a bit more long-range for your home, maybe consider ZigBee or Nordic Semi’s Bluetooth chips, as they can do over 1km in open terrain with the right antenna and PA.

      1. LoRa can’t be used like Wi-Fi or Bluetooth.” That is technically incorrect. LoRA is in the first place the physical layer. And in fact you can use it like WiFi, if you want to. What you are thinking about LoraWAN.
        You can always use Lora without LoraWAN, if you want to. Of course, no TTN endpoint is going to understand your packets, but if you don’t need that, it is fine.

        You also have a radio that isn’t capable of sending nearly as much data as Bluetooth can.
        Technically that isn’t a problem at all. Problem are only the duty-cycles. On some frequencies they are between 0.1% and 10%. But if they only want to it within a building, they can also use less power and Lora on 433 Mhz.

        1. Or lora on 2.4Ghz (sx1280) with the same power and duty cycle limits as any other standard usable in this band…

    1. @Deets said: “No IPEX modules in stock? Shortages?”

      Obviously none in stock direct from the manufacturer means yes, there is a shortage. There seems to be no shortage of modules without I-PEX connectors though. So I went looking for a shortage of I-PEX connectors… Nope, plenty available:


      The RAK3172 was announced back on at least 13-April-2021 (see Item-10):

      – Roundup: RAKwireless New IoT Offerings and Innovations Announced at Spring Launch Event April 13, 2021, 17:48 GMT


      So maybe the modules are just now hitting the market and there’s high demand for the I-PEX connector versions because I-PEX(M) to SMA(F) pigtails are cheap and readily available, which makes rapid prototyping easier.

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