Low Power IoT Design Challenge - Microwave Sensor

I'm going to reuse a remote microwave sensor that I had put together for another project and thought that I should show its implementation.  I am using an inexpensive RCWL-0516 sensor that others in the community have used.  It uses the Doppler frequency shift of a reflected 3 GHz signal to detect motion.  It has a nominal range of about 7 meters and provides a digital output when motion is detected.  You can adjust the range and retrigger time by adding a resistor and capacitor, but you can't get a distance measurement unless you hack into the intermediate analog signals on the detection chip.

Here's a front and back view.  Sensitivity is best orthogonal to the component side (front) of the board.

For rapid prototyping of WiFi/BLE enabled sensors, I've developed a preference for using M5StickC modules from M5Stack.  These modules are ESP32-based and are convenient to use because they include a small LCD screen and 95 mAh battery.  Below is the module that I set up.

I'm publishing the microwave detections and the battery voltage to my local RPi4 MQTT broker.  I also turn on the onboard LED when the detector triggers.

Here's a video showing the Node-Red MQTT Dashboard and its response to the microwave detector module.  The Status is either "Secure" or "Motion" if the detector is triggered.  The "Doppler" chart shows a time history of the trigger events - the output signal resets after about a second of inactivity.  You can also see the LED turn on for every detection.

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Low Power IoT Design Challenge - Microwave Sensor

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Because the battery on the M5StickC is so small, I use an 18650 rechargeable battery pack shown below when I deploy the unit.

In use, I can get detections consistently at about 6 meters which is sufficient for the path up to my entry door.  I have the option of directly connecting the sensor to the PSoC 62S2, but for now I'm going to leave it as a remote unit in case I want to reposition the detection zone.