This is a doppler radar module capable of detecting movement and can be used both with as well as without a microprocessor or microcontroller based development kit. The module is able to detect any movement in it’s path or nearby surroundings. The sensitivity of the module can be regulated by angling the module in certain ways to obtain the desired sensitivity. This module is inexpensive and can be easily used with other devices. It can find numerous applications in triggered alarm systems and home automation systems. The module consists of two antennas on the same board, one a transmitter antenna and another one a receiver antenna. The radar uses a unique doppler technique for the purpose of detecting movement in its path. It can detect movement even when it is kept in an insulated box. The device works on 4-28V DC and gives an output voltage of 3.3V DC.
How to use the module?
(i) Without Arduino Connections:
• Connect the Vin pin of the module to the positive terminal of a 5V DC supply
• Connect the GND pin of the module to the negative terminal of the 5V DC supply.
• Connect the negative terminal of the LED to the GND of the module.
• Connect the Positive terminal of the LED to one leg of the resistor (the sole purpose of this resistor is to protect the LED from getting damaged).
• Connect the open leg of the resistor to the output pin of the module.
Follow the above instructions or use the circuit diagram given below to easily connect the circuit.
(ii) With Arduino Connections:
• Connect the Vin pin of the module to the 5V pin of the Arduino.
• Connect the GND pin of the module to the GND pin of the Arduino.
• Connect the negative terminal of the LED to the common GND.
• Connect the positive terminal of the LED to one leg of the resistor.
• Connect the other leg of the resistor to digital pin 13 of the Arduino.
• Connect one leg of the pushbutton to the common GND of the circuit.
• Connect the opposite leg of the pushbutton digital pin 3 of the Arduino.
• Connect the same leg of the pushbutton to a resistor and the other end of the resistor to the 5V pin of the Arduino.
• Connect the OUTPUT pin of the RCWL module to the digital pin 2 of Arduino.
Connect the circuit according to the above instructions or follow the diagram given below. Please know that when the pushbutton is used in this configuration, it gives a digital output LOW when pressed.
According to the above code whenever there is a movement in the detection range of the sensor the LED will light up, we can use the pushbutton to turn OFF the LED. This mechanism can be seen as us arming the microwave sensor alarm system every time we press the pushbutton. We can also add an LDR to the above circuit by connecting it to the CDS pin of the module to detect any movement in the absence of light.