Test GPIO pins on BeagleBone Black by toggling high to low

Tutorial: Test GPIO pins on BeagleBone Black using Bash
This tutorial describes how to write and execute a Bash script to test the GPIO pins on the BeagleBone Black. GPIO (General Purpose Input/Output) pins are versatile and can be controlled programmatically. Here we will guide you step by step to toggle GPIO pins using a simple script.

1. Prerequisites Before you begin, make sure you meet the following:

You can use the BeagleBone Black board.
The motherboard runs a Linux-based operating system.
You have root access (some operations require elevated privileges).
Your motherboard’s GPIO pin numbers and mappings are known.

1. Understanding GPIO Pins GPIO pins are accessible through the Linux file system under /sys/class/gpio. Each GPIO pin is represented by a number that you can use to control its state. For example:

P8 pin 12 corresponds to GPIO1_12, and the GPIO number is 44.
The formula for calculating the number of GPIOs is:
GPIO pin = (Bank number × 32) + pin number.
For more information, see BeagleBone Black GPIO Pinout.

1. Script Overview This script does the following:

Export GPIO pins for user control.
Set the pin direction to output.
Switch the pin status (high/low) 3 times with an interval of 1 second.
Cancel the export pin after testing.

1. Bash Script This is the script:

#!/bin/bash

# Define the GPIO pin to test
# Examples of GPIO numbers:
# P8 Pin 11 -> GPIO1_13 = 45
# P8 Pin 12 -> GPIO1_12 = 44
# P8 Pin 14 -> GPIO0_26 = 26
# P8 Pin 16 -> GPIO1_14 = 46

TESTPIN=44  # Replace with your target GPIO pin number

# Export the GPIO pin to make it available
echo "$TESTPIN" > /sys/class/gpio/export

# Set the direction of the pin as output
echo "out" > /sys/class/gpio/gpio$TESTPIN/direction

# Toggle the pin value HIGH and LOW three times
for i in {1..3}; do
  echo "Setting gpio$TESTPIN HIGH"
  echo "1" > /sys/class/gpio/gpio$TESTPIN/value
  sleep 1  # Wait for 1 second

  echo "Setting gpio$TESTPIN LOW"
  echo "0" > /sys/class/gpio/gpio$TESTPIN/value
  sleep 1  # Wait for 1 second
done

# Unexport the GPIO pin after testing
echo "$TESTPIN" > /sys/class/gpio/unexport

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