Introduction
In this lesson, we will learn how to make eight LEDs blink in various effects as you want based on Raspberry Pi.
Components
– 1*Raspberry Pi
– 1*Breadboard
– 1*Network cable (or USB wireless network adapter)
– 8*LED
– 8*Resistor (220Ω)
– Jumper wires
Experimental Principle
Set GPIO0 to GPIO7 to low in turn by programming, then LED0 to LED7 will light up in turn. You can make eight LEDs blink in different effects by controlling their delay time and the order of lighting up.
Experimental Procedures
Step 1: Connect the circuit as shown in the following diagram
Step 2: Edit and save the code with vim (see path/Rpi_BasicKit /02_8led/8Led.c)
Step 3: Compile the code
| gcc 8Led.c -lwiringPi |
Step 4: Run the program
| ./a.out |
Now, when you press Enter, eight LEDs will light up circularly and render different effects.
Further Exploration
We can write the blinking effects of LEDs in an array. If you want to use one of these effects, you can call it in the main() function directly.
C Code
| #include <wiringPi.h> #include <stdio.h>#define LedPin 0int main(void) { if(wiringPiSetup() == -1){ //when initialize wiring failed,print messageto screen printf(“setup wiringPi failed !”); return 1; } printf(“linker LedPin : GPIO %d(wiringPi pin)\n”,LedPin); //when initialize wiring successfully,print message to screen pinMode(LedPin, OUTPUT);while(1){ digitalWrite(LedPin, LOW); //led on delay(500); digitalWrite(LedPin, HIGH); //led off delay(500); }return 0; } |
Python Code
| #!/usr/bin/env python import RPi.GPIO as GPIO import time pins = [11, 12, 13, 15, 16, 18, 22, 7] def setup(): GPIO.setmode(GPIO.BOARD) # Numbers GPIOs by physical location for pin in pins: GPIO.setup(pin, GPIO.OUT) # Set all pins’ mode is output GPIO.output(pin, GPIO.HIGH) # Set all pins to high(+3.3V) to off led def loop(): while True: for pin in pins: GPIO.output(pin, GPIO.LOW) time.sleep(0.5) GPIO.output(pin, GPIO.HIGH) def destroy(): for pin in pins: GPIO.output(pin, GPIO.HIGH) # turn off all leds GPIO.cleanup() # Release resource if __name__ == ‘__main__’: # Program start from here setup() try: loop() except KeyboardInterrupt: # When ‘Ctrl+C’ is pressed, the child program destroy() will be executed. destroy() |