Hi-Link LD1125H: Reverse Engineering a cheap 24GHz FMCW Radar - Part II

 Date: December 28, 2024

First attempts of writing a new firmware for this small FMCW radar turned out to be successful: The device is able to send out a static CW signal and receive its down-mixed doppler signal.

To keep it simple the entire firmware is super minimalistic:

  • Setting a static DAC value to PA4
  • ADC DMA which writes into a double buffer at 50kHz
  • UART DMA reads out this buffers and writes it onto the interface at 2MBaud
  • This then is getting parsed by a Python script which calculates the FFT at 10fps

The data transmission is not very robust - just sending raw samples with a small start-of-transmission marker without any checksum.

The entire firmware can be found here.

A small demo with a spinning fan was recorded:

LD1125H in CW mode. The spectrum is the FFT'ized Bang signal.

This project will stop at this point as the lacking separate I/Q channels limits the use of this board.


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⏪ Hi-Link LD1125H: Reverse Engineering a cheap 24GHz FMCW Radar - Part I

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MicRadar R24BBD1: Reverse Engineering another 24GHz CW radar ⏩