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Arduino And The RWCL-0516 Subsystem
| Gene's Quick  Lab Ref

2017 OCTOBER | Gene Casanova

Senior Systems Engineer

Embedded Electronics

Solid State Electronics Combined With Microcontrollers And Synthetic Logic (AI)..... Clear Your Mind Of Silly Movie Ideas, And Open Your Mind To New Concepts And Perspective; Evolve A Attitude, And Welcome Effective Enlightenment To AI..... Discover The Next Realm Of Reality On Earth = Smart Machines...

.....Gene Casanova circa 1978

What Is RWCL-0516?

The RCWL-0516 is a microwave radar integrated circuit subsystemboard; intended to be a sensor switch; made available by CGI Computer Wares, located in Industrial Milwaukee WI USA; in the Great Lakes Region of USA.

The RCWL-0516 subsystemboard is intended for controlling devices; such as light sources (room lamps and wall mounted lights); by motion detection, and turn off after a short period of time has passed (a timeout).

The RCWL-0516 radar subsystemboard, provides a low-power consumption, low-power output, short-range (~~5m) dopiler radar.

RCWL-0516 is a doppler radar microwave motion sensor subsystemboard with sensor antenna onboard.

The front side of the systemboard is the side with components.  This side is the detection side; emitting the radar radiation; creating the invisable radar detection area.

Do not obstruct the forward side of the PCB with anything metalic or liquid.

The back side should have clearance of more than 1cm from any metal.

Doppler Radar

A critical function of a doppler radar is to be able to 'mix' the reflected signal with the transmitted signal to arrive at a frequency which is the difference between the transmitted and reflected signal.

RCWL-0516 RADAR Pattern

The front side must not be blocked by any metal.

A minimal space of 1cm is required in front and back of PCB.

Night detecting function onboard on /off optional control.

Adjustable repeat trigger time.

Adjustable detecting distance = by adding SMD components to the corresponding pins.

RCWL-0516 Pinouts


It provides a 3.3V output to drive a MCU (good for 100mA ?).
Commnd Circuit Ground Connection; -VDC
Data Output; Trigger: HIGH (3.3V) when motion detected. 0V standby.
VIN (Vcc)
4 - 28+ VDC Supply.
Output 0.7 VDC; Photo Cell (CdS) photoresistor PCB location.  Appears to be an optional component and fucntional feature of the detection circuit.  The RCWL-0516 does not come with a CDS insatlled.

A 'CdS' cell is a light sensor component. As a CdS is exposed to more light, the resistance of the device, descreases.

Understand Doppler Radar To Use This Subsystem

Research the scienetific principle (physics) doppler radar is based on, and the functiionality of a doppler radar system.

Principles of Doppler Radar

The "Doppler- Effect" is the apparent change in frequency or pitch, when a sound source moves either toward or away from the listener, or when the listener moves either toward or away from the sound source. This principle, discovered by the Austrian physicist Christian Doppler, applies to all wave motion.

Christian Doppler explained in 1842, when one stands near a railroad track, listening to the sound of a train passing, the train sounds different, as it approaches, than it does, as it recedes.  This change is known as the "Doppler effect".

Doppler radar can measure the velocity of targets relative to the radar.

The radar creates an electromagnetic energy pulse; focused by an antenna, and transmitted through the atmosphere.

An object in the path of this electromagnetic pulse, referred to as "target", scatters the electromagnetic energy.  Some of this energy is scattered back towards the radar device.

The receiving radar antenna (typically the same transmitting antenna) collects this back-scattered radiation, and feeds it to a device referred to as a "receiver".

The wavelength of a radio-wave is the distance between one crest of a wave to the next crest of a wave.

The phase of a wave, measured in degrees, where 360 degrees is one wavelength, indicates the current position of the wave relative to a reference position.  When the radar radio wave position changes, relative to the vertical line, this is referred to as a "phase shift".

Of interest, is the signal component received back at the radar.  A received signal is typically much weaker than the original sent from the transmitter, and is referred to as the "return signal".

The quantity of a radar measurement, is the returned power which, with knowledge of other radar characteristics, is converted to a quantity unit referred to as the "reflectivity factor", or shorten to "reflectivity".

The factors governing the choice of a wavelength to be used in a particular radar, include, sensitivity, which is its ability to detect weak targets at long range, the radar ability to resolve small features, the types of targets to be studied, and the effects of the intervening atmosphere on the transmitted energy.  Other factors must be considered, such as radar size, weight, and cost.  Most weather radars have wavelengths ranging between 0.8 centimeters (cm) and 10.0 cm.  Generally short wavelengths mean smaller and less expensive equipment.

Short wavelength radars are more effective in detecting small particles. Short wavelength electromagnetic energy, is partially absorbed by particles (a process referred to as "attenuation").  This makes it difficult to accurately measure the intensity of back-scattered energy, for more distant targets, beyond the range of closer targets.

In practice the Doppler-frequency occurs twice at a radar.  Once on the way from the radar to the aim, and then for the reflected (and already afflicted by a Doppler-shift) energy on the way back.

Locating A Target

A radar needs 3 pieces of information to determine the location of a target.

The first piece of information is the angle of the radar beam with respect to north; called the "azimuth angle".

The second is the angle of the beam with respect to the ground; called the "elevation angle".

The third piece of information needed is the distance (D) from radar to target.

A Quick Look, Arduino & RWCL-0516

The following Arduino probe program, can be used to detect and display the output from an RWSL-0516 sensor board.

Load the following Arduion RWCL-0516 C source code (sketch) in an Arduino, using the Arduino IDE application:

void setup() {
void loop() {

Using Advanced Arduion IDE Features

When writting output fromt he sensor, begin by writting a zero value, followed by the utput data, followed by the value '4500'. The beginning zero and the ending '4500' are used to set the range of the Arduino IDE "Plotter" function; utilizing the "auto ranging" feature.

Arduion Doppler Radar

Quick And Simple Tinker Radar Sesnor

A working doppler radar using an Arduino UNO, a RWCL-0516 subsystemboard, and the following program, written in Arduino C source code (sketch):

/* Doppler Radar Sensor v1.2
 * Doppler_Radar_Sensor.c
 * By Gene Casanova
 * Source Code fixed & edited version.
 * 2017 October
 * Copyright - Must Retain.
 * Private Use granted.
 * Commercial Use Must Obtain License.
const int pinSensor = 8;
const int pinLed = 3;
int ismotion;

void setup() {
Serial.begin(9600); //Begin a serial interface @ 9600 baud.
pinMode (pinSensor, INPUT); // Set sensor pin to INPUT Mode.
pinMode (pinLed, OUTPUT); // Set LED pin to OUTPUT mode.
void loop() {
ismotion = digitalRead(pinSensor); // Read Sensor Pin. if(ismotion == 1){ // Sensor Detected Difference.
digitalWrite(pinLed,HIGH); // Enable LED pin.
Serial.println("Detect"); // Output "Detect" Report to Serial Port Connected Console.
Serial.println("No Detect");


Sensor Sysmboard PinsArduino UNO Pins
3V3N/C (no connection)
OUTDigital Pin 8



The University of Illinois at Urbana-Champaign, IL, USA. http://ww2010.atmos.uiuc.edu/(Gh)/home.rxml


Use The Technology Wisely & Keep It Simple

- Cheers!

Gene Casanova

Software, Network, System & Data Center Builder & Developer | Development Services Available - Documentation Writing; Freelance Small Jobs; To Outsourced Long Term Service Provider Contract Labor Available.

CGI Computer Wares | EST 1979

Send E-MailCONTACT : [click]@CGIComputerWares.com