IR Presence Detector with Smart Pi One

In this guide, we will demonstrate how to read the values from an IR presence detector connected to the Smart Pi One, using the SmartPi-GPIO library.

We will cover the following methods: - CLI commands - Python script

Required Materials

• Smart Pi One
• IR presence detector (e.g., HC-SR501 or similar)
• Connecting wires
• Breadboard (optional for easier connections)

Wiring Diagram

The IR presence detector typically has three pins: VCC, GND, and DOUT (digital output).

• VCC connects to 3.3V (Pin 1).
• GND connects to Ground (Pin 6).
• DOUT connects to GPIOG11 (Pin 7) to read the presence detection signal.

Pin Number	Pin Name	Function
1	3.3V	Power Supply
7	GPIOG11	IR Presence Output
6	GND	Ground

Prerequisites: Configuration of smartpi-gpio

To install SmartPi-GPIO on your Smart Pi One, follow these steps:

1. Update system:

sudo apt update 
sudo apt-get install -y python3-dev python3-pip libjpeg-dev zlib1g-dev libtiff-dev
sudo mv /usr/lib/python3.11/EXTERNALLY-MANAGED /usr/lib/python3.11/EXTERNALLY-MANAGED.old

1. Clone the repository:

git clone https://github.com/ADNroboticsfr/smartpi-gpio.git
cd smartpi-gpio

1. Install the library:

sudo python3 setup.py sdist bdist_wheel
sudo pip3 install dist/smartpi_gpio-1.0.0-py3-none-any.whl

1. Activate GPIO interfaces:

sudo activate_interfaces.sh

Reading Values via CLI

You can read the values from the IR presence detector using the CLI.

Steps:

1. Configure the pin for digital input:

sudo gpio 7 mode in

1. Example to read and display values continuously: Use a loop to read the state of the IR presence detector and print a message only when presence is detected:

while true; do
  value=$(sudo gpio 7 read)
  echo "IR presence detector value: $value"
  sleep 1
done

This will display "IR presence detector value: Pin 7: 1" when the detector senses something.

Using Python

Reading Values with Python

With SmartPi-GPIO and Python, you can write a simple script to read the value from the IR presence detector.

Steps:

1. Create a Python file:

nano ir_presence_detector_read.py

1. Write the following code:

from smartpi_gpio.gpio import GPIO
import time

# Initialize GPIO instance
gpio = GPIO()

# GPIO pin number for the IR presence detector (GPIO7)
ir_detector_pin = 7

# Configure the pin as input
gpio.set_direction(ir_detector_pin, "in")

print("Reading values from the IR presence detector...")

try:
    while True:
        # Read the value from the IR presence detector
        value = gpio.read(ir_detector_pin)
        if value == '1':  # Presence detected
            print("Presence Detected!")
        time.sleep(1)  # Read every second
except KeyboardInterrupt:
    print("Exiting...")

1. Save and exit (CTRL+X, Y, and Enter).

2. Run the Python script:

sudo python3 ir_presence_detector_read.py

This will continuously display "Presence Detected!" when detection occurs.