Uploaded August 2026 | Updated September 2026, 3 weeks ago

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No camera. No light. This little board still knows where you're standing — and it gives you real X/Y coordinates for up to 3 people at once.

It's an HLK-LD2450: a 24GHz mmWave radar with one transmit and two receive antennas on a 44 × 15 mm board. It streams target positions over UART to an ESP32-S3, which plots them live on a 4.2" reflective LCD — no backlight, so it actually gets easier to read in direct sunlight.

Honest verdict after a day of outdoor testing: distance tracking is solid, but side-to-side movement is weak. That's physics, not a bad part — Doppler radar only measures motion toward or away from the sensor, so walking across the beam looks like standing still. Still plenty good for presence, wake-on-approach, and automatic lighting.

More tests coming. What should I try next?

Build:
· HLK-LD2450 24GHz mmWave radar
[amzn.to/4gApzoP]
· ESP32-S3 + 4.2" reflective LCD, 400 × 300, 1-bit
[waveshare.com/esp32-s3-rlcd-4.2.htm?&aff_id=116255]
· 3D-printed bracket, M2.5 mount

#mmwave #radar #esp32 #esp32s3 #electronics #diyelectronics #maker #embedded #3dprinting #sensors #homeautomation #shorts