GPIO (General-Purpose Input/Output) is a flexible interface found on microcontrollers, single-board computers (like Raspberry Pi), and other embedded systems. It allows these devices to interact with external components or circuits by providing programmable digital pins that can be configured as either inputs or outputs.
https://www.sinsmarts.com/blog/what-is-a-gpio/
Key Features:
Digital Signals:
GPIOs handle binary signals: HIGH (1) or LOW (0), typically represented by voltage levels (e.g., 3.3V or 5V for HIGH, 0V for LOW).
Programmable Direction:
Input Mode: Reads external signals (e.g., detecting a button press or sensor state).
Output Mode: Sends signals to control external devices (e.g., lighting an LED, driving a relay).
No Built-in Functionality:
GPIOs have no predefined purpose—their behavior is defined entirely by software. This makes them versatile but requires manual configuration.
Common Use Cases:
Input Examples:
Reading data from buttons, switches, or motion sensors.
Receiving signals from digital communication protocols (e.g., I²C, SPI, UART—though these often use dedicated pins).
Output Examples:
Turning LEDs on/off.
Controlling motors via driver circuits.
Sending signals to displays or other peripherals.
Important Considerations:
Voltage Compatibility: GPIOs operate at specific voltages (e.g., 3.3V on Raspberry Pi, 5V on Arduino). Exceeding these can damage the pin or device.
Current Limits: GPIO pins can usually source/sink only small currents (e.g., ~16mA per pin on Raspberry Pi). Always use resistors (e.g., for LEDs) or driver circuits (e.g., transistors) for higher loads.
No Analog Support: GPIOs are digital-only. For analog signals (e.g., reading a potentiometer), an ADC (Analog-to-Digital Converter) is required.
Software Control: Configuration and operation rely on code (Python, C, etc.). Libraries like RPi.GPIO (Raspberry Pi) or wiringPi simplify programming.
Example on Raspberry Pi:
python
import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BCM) # Use Broadcom pin numbering
led_pin = 18 # Assign GPIO18
button_pin = 24 # Assign GPIO24
Configure pins:
GPIO.setup(led_pin, GPIO.OUT) # Set LED pin as OUTPUT
GPIO.setup(button_pin, GPIO.IN) # Set button pin as INPUT
Turn LED on when button is pressed:
while True:
if GPIO.input(button_pin) == GPIO.HIGH:
GPIO.output(led_pin, GPIO.HIGH) # LED ON
else:
GPIO.output(led_pin, GPIO.LOW) # LED OFF
Summary:
GPIO pins are the "swiss army knife" of hardware interfaces, enabling basic but critical interactions between a computing device and the physical world. They are essential for DIY electronics, IoT projects, robotics, and automation. Always refer to your device’s documentation to avoid misuse!
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