Micropython PIR example for the Raspberry Pi Pico

In this example we connect a PIR module up to our Raspberry PI Pico, this is quite a simple module to connect as it requires only 3v3, Gnd and the output is ok to connect to a Pico  and does not require any level shifting.

A passive infrared sensor (PIR sensor) is an electronic sensor that measures infrared (IR) light radiating from objects in its field of view. They are most often used in PIR-based motion detectors.

Here is a typical collection of PIR detectors which can be commonly found on the internet and can be used in many projects. They all should work Ok, I have tested the bigger one at the top and the SR602 one at the bottom with the same results.

Interestingly the sensor can be adjusted using the 2 pots on it which you can see underneath

Adjust the distance potentiometer clockwise rotation, increased sensing distance (about 7 meters), on the contrary, the sensing distance decreases (about 3 meters).

Adjust the delay potentiometer clockwise rotation sensor the delay lengthened (300S), on the contrary, shorten the induction delay (5S).

Induction module needs a minute or so to initialize. During initializing time, it will output 0-3 times. One minute later it comes into standby.

Parts Required

The PIR is low cost and you should be able to get one for under $1

Name	Link
Pico	Raspberry Pi Pico Development Board
PIR	HC-SR501 HC-SR505 SR602 AM312 PIR Motion Sensor Detector Module
Connecting cables	Aliexpress linkAmazon.com link Ebay link

 

Schematic/Connection

Black for GND
Red for V+
Yellow for Output

So color coded for ease of use, this layout shows a connection to the module

Code Example

I used Thonny for development, you can use any GPIO pin but you would need to alter the code below.

[codesyntax lang=”python”]

from machine import Pin
import utime
from time import sleep

# Connect GP16 to PIR sensor's OUT pin), please use 3.3V connect to VCC on PIR sensor.
pir = Pin(16, Pin.IN, Pin.PULL_UP)


while True:
    print(pir.value())
    sleep(0.1)

[/codesyntax]

This has a simple output, if no object is detected then 0 is output, if an object is detected then a 1 will be outputted

Here is an adapted example with easier to read output

[codesyntax lang=”python”]

from machine import Pin
import utime
from time import sleep

# Connect GP16 to PIR sensor's OUT pin), please use 3.3V connect to VCC on PIR sensor.
pir = Pin(16, Pin.IN, Pin.PULL_UP)


while True:
  if pir():
    print('Motion detected!')
    sleep(5)
    if not pir():
        print('Motion stopped')

[/codesyntax]

Output

Here is what I saw in Thonny REPL window

Motion detected!
Motion stopped
Motion detected!
Motion stopped

Links