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.
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.
