MR24HPC1 mmWave Sensor Shows "Unknown" States with ESP32C3

Hi everyone! :wave:

I’m working on integrating a MR24HPC1 mmWave sensor with an ESP32C3 Supermini (Tenstar Robot) through ESPHome. While the device connects beautifully to Home Assistant, I’m hitting a wall where all sensor states remain “Unknown”. I’m hoping someone might spot what I’m missing.

Hardware Setup

Components:

  • ESP32C3 Supermini (Tenstar Robot)
  • MR24HPC1 mmWave Sensor
  • ESPHome 2024.12.2
  • Latest Home Assistant Core

Connections:

ESP32C3 Pin MR24HPC1 Pin
5V VCC
GND GND
GPIO4 (D2) RX
GPIO5 (D3) TX

Current Status

What’s Working:

  • Device connects to WiFi perfectly (signal strength: -41 dB)
  • Shows up in Home Assistant correctly
  • ESPHome compilation and installation successful
  • All logs look clean and normal
  • OTA updates configured and working

The Issue:

  • All sensor entities show as “Unknown”
  • Includes presence detection, motion sensors, distance measurements
  • No sensor data seems to be transmitted at all
  • UART communication appears configured but might not be working

Configuration Highlights

Key parts of my YAML:

uart:
  id: uart_bus
  baud_rate: 115200
  rx_pin: 4
  tx_pin: 5
  parity: NONE
  stop_bits: 1

seeed_mr24hpc1:
  id: my_seeed_mr24hpc1

# Full sensor configuration available if needed

What I’ve Tried

  • Flashed firmware both directly and through ESPHome Builder
  • Double-checked all wiring multiple times
  • Verified power supply is stable
  • Enabled DEBUG logging level
  • Checked UART configuration against documentation
  • Tried with and without the external components source

Could this be a UART communication issue that I’m not seeing in the logs? Any ideas what else I should check?

Thanks for any help! :pray:

Have you really checked for the right pinout? Because the C3 variants got quite big differences there.

1 Like

Yes i did. Sadly this is not the explaination, hower thanks for the reminder - could have been an easy fix.