Controlling an LED via GPIO on Smart Pi One

This page describes how to control an LED using GPIO on the Smart Pi One, with detailed steps, wiring instructions, a wiring diagram, and code examples in both Python and C.

Required Materials

• Smart Pi One
• LED (with resistor around 220Ω to 1kΩ if necessary)
• Connecting wires
• Breadboard (optional for easier connections)

Wiring Diagram

Below is the wiring diagram for connecting an LED to GPIO on the Smart Pi One

Connecting the LED

Connect the LED: - Connect the longer leg of the LED (anode) to GPIO (GPIO7/PIN: 7). - Connect the shorter leg of the LED (cathode) to ground (GND/PIN:9). - If necessary, place a resistor in series with the LED to limit the current (typically around 220Ω to 1kΩ).

Turning on an LED 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 led_control.py

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

import time
from smartpi_gpio.gpio import GPIO

# Initialize GPIO
gpio = GPIO()

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

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

        # Turn off the LED
        gpio.output(7, gpio.LOW)
        print("LED 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:

sudo python3 led_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 led_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 LED
    smartpi_gpio_set_mode(7, OUTPUT);

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

        // Turn off the LED
        smartpi_gpio_write(7, LOW);
        printf("LED 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 led_control led_control.c -I/path/to/smartpi_gpio/include -L/path/to/smartpi_gpio/lib -lsmartpi_gpio
sudo ./led_control