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