Open PIR (Passive Infrared Sensor)

Open PIR - Passive Infrared Sensor

13968-01

PIR

  • Human or animals will emit heat (as infrared radiation)
  • Senses infrared waves to detect motion
  • Uses
    • Alarms
    • Motion sensing cameras / lights
  • Not a distance sensor

PIR Specifications

  • Distance range: up to 16 feet
  • Detection range: ~110 degrees x 70 degrees
  • Specifications vary by device and lens

Components

  • Main sensor is the small metal disc which detection infrared radiation

image-20240422104044162

## Components

  • Clear / white lenses acts to focus a wider area of radiation onto the sensor to increase range

13968-04

Operation (Sparkfun PIR)

  • Requires 1-2 sec delay in setup() to get initial reading from room
  • Digital output from OUT pin
  • HIGH when no movement detected
  • LOW when movement detected
  • Sensitive adjustment (screwdriver)
  • Time adjustment (screwdriver)
  • Single / dual swtich

Sensitivity Adjustment (SEN)

openpir_pots

  • Sensitivity (potentiometer): how much motion triggers alarm
  • Adjust the view distance of the OpenPIR
  • Clockwise turn increase the distance the sensor sees
  • you turn this trimpot, the further your sensor should be able to see. When you receive the board, the trimpot will be centered, and the sensor will react to a person moving about in the 6 to 8 foot (2 to 2.5m) range. At the maximum sensitivity, the sensor will detect a person walking by at about 16 feet (5m).Other PIR sensors have different configurable options

Time Adjustment (SEN)

openpir_pots

  • Time adjust (potentiometer): how long after motion stops does signal remain active
  • Adjust the length of time the output remains HIGH. This trimpot is used to adjust the oscillator frequency of the NCS36000.
  • Clockwise increases the length of time OUT remains high
  • Time range: 400 ms to 7.5 s

Retriggering

openpir_switch_1

  • Retriggering (switch / jumper): controls if alarm stays active for the same movement
  • Controls if alarm stays active for the same movement
  • Single-pulse mode can be used to detect an object entering or exiting the PIR’s field-of-view
  • Dual-pulse detection can be used to detect an object entering and leaving the view area.

Wiring

Open PIR (Sparkfun) Photon 2
VCC 3.3v
GND GND
OUT Any digital pin
A (Optional) Any analog pin

Note: The wire color and pin order is specific to the Sparkfun OpenPIR sensor and not all PIR sensors

Wiring

Screenshot 2024-06-29 at 11.44.31 PM

Exercise

  • Part 1: Connect sensor; turn on on-board LED when motion is detected and turn off when motion stops
  • Part 2: Adjust the potentiometers to experiment with the view distance and and hold length

Credit

Updated: