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12. Input Devices (Indonesia group)

This is group assignment page of Input Devices (Indonesia Student) :

Group assignment:

  • probe an input device’s analog levels and digital signals

In this weekly assignment we will take measurements on:

  • Gas Sensor MQ-02 (Analog)
  • PIR Sensor HC-SR301 (digital)

MQ-02 (Gas Sensor)

MQ-02 is a sensor for detecting gas in general (general combustible gas).

Technical data from the sensor as follows

the datasheet can be seen here

In this task we try to run this sensor and then measure the value of the voltage generated when there is a change in environmental conditions (gas)

When idle, the sensor shows a voltage of 1.3V. When there is combustion gas detected by the MQ-02 sensor, the voltage issued by the sensor rises to 2.3V. The signal pattern changes gradually indicating the type of analog signal. The greater the combustion gas captured by the sensor, the greater the voltage issued by the sensor to the MCU

HC-SR301 (PIR Sensor)

This sensor is a Passive Infrared Receiver (PIR) motion detection sensor.


  • Working voltage: DC 2.7-12V
  • Static power consumption: <0.1mA
  • Delay time: 2 seconds
  • Blocking time: 2 seconds
  • Trigger: can be repeated
  • Sensing range: 100 degree cone angle, 3-5m (depends on lens)
  • Working temperature: -20~+60C
  • PCB Dimension: 10x8mm
  • Total size: 12x25mm
  • Module Lens: Small Lens

We try to use this sensor to detect motion in front of the sensor. If there is movement then the sensor will send a digital signal. We will capture the signal sent using an oscilloscope.

In this sensor the type of signal that is issued is a digital signal (high or low). when the sensor detects movement, the sensor will issue a “HIGH” value (this sensor detects a high voltage value of 3.4 V). whereas when no motion is detected, no output voltage is output.

Last update: June 25, 2022