Activating a Relay on Smart Pi One

This page describes how to activate a relay using the Smart Pi One, with detailed steps, wiring instructions, and code examples in both Python and C.

Required Materials

• Smart Pi One
• Relay module (with optoisolator recommended)
• Connecting wires
• Breadboard (optional for easier connections)

Wiring Diagram

Below is a sample wiring diagram for connecting a relay module to the Smart Pi One:

Connecting the Relay

1. Connect the Relay:
2. Connect the input pin of the relay module (IN) to a GPIO pin on the Smart Pi One (GPIO7/PIN: 7).
3. Connect the VCC pin of the relay module to the (5V/PIN:2) on the Smart Pi One.

4. Connect the GND pin of the relay module to the ground (GND/PIN:3) pin on the Smart Pi One.

5. Connect the Load:

6. Connect the device you want to control (e.g., a lamp) to the relay's output terminals. Ensure proper electrical connections are made according to the relay's specifications.

Turning on a RELAY via Command Line (CLI)

Step 1: Turn on the LED

To turn on the LED on GPIO 7:

gpio -g mode 7 out
gpio -g write 7 1

Step 2: Turn off the LED

To turn off the LED:

gpio -g write 7 0

Using Python

Prerequisites: Configuration of smartpi-gpio

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

1. Update system: ```bash 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

2. Clone the repository: ```bash git clone https://github.com/ADNroboticsfr/smartpi-gpio.git cd smartpi-gpio

3. Install the library: ```bash sudo python3 setup.py sdist bdist_wheel sudo pip3 install dist/smartpi_gpio-1.0.0-py3-none-any.whl

4. Activate GPIO interfaces: bash sudo activate_interfaces.sh pip install smartpi-gpio

Creating the Python Script

1. Open a terminal on your Smart Pi One.
2. Create a new Python file using nano:

nano relay_control.py

1. Copy and paste the following Python code into the file:

import time
from smartpi_gpio import GPIO

# Initialize GPIO
gpio = GPIO()

# Set GPIO7 as output for the relay
gpio.setup(7, gpio.OUT)

try:
    while True:
        # Activate the relay (turn on)
        gpio.output(7, gpio.HIGH)
        print("Relay is ON")
        time.sleep(2)  # Keep it on for 2 seconds

        # Deactivate the relay (turn off)
        gpio.output(7, gpio.LOW)
        print("Relay is OFF")
        time.sleep(2)  # Keep it off for 2 seconds
except KeyboardInterrupt:
    pass
finally:
    gpio.cleanup()  # Clean up GPIO

1. Save the file by pressing CTRL + X, then Y, and finally Enter.

Running the Python Script

To run the Python script, use the following command:

python3 relay_control.py

Using a C Program

Creating the C Program

1. Open a terminal on your Smart Pi One.
2. Create a new C file using nano:

nano relay_control.c

1. Copy and paste the following C code into the file:

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "smartpi_gpio.h"

int main() {
    // Initialize GPIO
    smartpi_gpio_init();

    // Set GPIO7 as output for the relay
    smartpi_gpio_set_mode(7, OUTPUT);

    while (1) {
        // Activate the relay (turn on)
        smartpi_gpio_write(7, HIGH);
        printf("Relay is ON\n");
        sleep(2);  // Keep it on for 2 seconds

        // Deactivate the relay (turn off)
        smartpi_gpio_write(7, LOW);
        printf("Relay is OFF\n");
        sleep(2);  // Keep it off for 2 seconds
    }

    // Release GPIO resources (this will never be reached)
    smartpi_gpio_cleanup();
    return 0;
}

1. Save the file by pressing CTRL + X, then Y, and finally Enter.

Compiling and Running the C Program

To compile and run the C program, use the following commands:

gcc -o relay_control relay_control.c -I/path/to/smartpi_gpio/include -L/path/to/smartpi_gpio/lib -lsmartpi_gpio
./relay_control