Sparkfun’s Pulsed Coherent Radar Sensor features Acconeer XM125 60 GHz module, works through walls, offers up to 20-meter range

SparkFun has launched a new Qwiic breakout board for the Acconeer XM125 60 GHz pulsed coherent radar sensor that can measure distance to humans even through walls and works at a distance of up to 20 meters.

We’ve seen tiny 24GHz or 60GHz radar modules for several years now, and Supachai even reviewed the Seeed Studio mmWave sensor using ESPHome and Home Assistant late last year with the solution relying on Frequency-Modulated Continuous Wave (FMCW) technology. The Acconneer XM125 is a Pulse-radar module that emits electromagnetic waves in short bursts instead of continuously like FMCW radars and allows longer measurement ranges potentially at the cost of lower accuracy.

SparkFun Pulsed Coherent Radar Sensor Acconeer XM125 Qwiic

Sparkfun Pulse Coherent Radar Sensor specifications:

  • Acconeer XM125 Module
    • A121  60GHz Pulsed Coherent Radar (PCR)
      • Integrated baseband, RF front-end, and antenna in package
      • Detects distance, speed, motion, and objects up to 20 meters away
      • Millimeter precise readings
      • Low power consumption
    • STMicro STM32L431CBY6 32-bit Arm Cortex-M4 MCU clocked up to 80 MHz, with 128KB flash, 68KB SRAM
    • Dimensions – 18.6 x 15 mm
  • USB – 1x USB Type-C connector with ESD protection diodes for data lines, CH340C USB-to-Serial converter
  • Expansion
    • 2x horizontal Qwiic connectors
    • 11-pin + 9-pin headers with GPIO, I2C, UART, SWD, 5V, 3.3V, 1.8V, GND…
  • Debugging – 2×5 SWD header footprint
  • Misc
    • Reset and Boot buttons
    • Power LED
    • Jumpers
      • USB Shield (SHLD)
      • Power LED (LED)
      • I2C Pull-Up Resistors (I2C)
      • Wake Up (WU)
      • I2C Address (ADDR) – Not implemented yet, and the address is currently fixed to 0x52
  • Power Management
    • Voltage – 5V or 3.3V but all logic is 3.3V
    • AP2112K 3.3V/600mA voltage regulator
    • RT9080 1.8V/600mA voltage regulator
  • Dimensions – 50.8 x 25.4mm
  • Weight – 6.35 grams

60 GHz mmWave radar sensor through walls


The module is open-source hardware and Sparkfun provides the PDF schematics and Eagle hardware design files. There’s also an Arduino library on GitHub and instructions to get started can be found on the documentation website. The XM125 breakout board needs to be connected to an Arduino-compatible board with a Qwicc connector and relies on both Arduino code and STM32 tools, with Sparkfun mentioning it’s not quite as easy to use as their other boards as some extra steps are required.

Besides measuring distances with millimeter precision, the module can also detect motion, measure the speed of an object, and support gesture recognition. You can watch a video of distance measurement (to a human) in the video below including a demo that shows it working through a wall, something that’s not possible with ultrasonic or ToF sensors.

Sparkfun sells the “Pulsed Coherent Radar Sensor – Acconeer XM125 (Qwiic)” module for $49.95 plus shipping.

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