On Raspberry PI I use the WiringPi library for both C and Python development. Below is an example of cycling through three GPIO pins to light up a set of LEDs.
- GPIO 17 – Pin 6 maps to the WiringPi logical pin 0
- GPIO 22 – Pin 7 maps to the WiringPi logical pin 2
- GPIO 27 – Pin 7 maps to the WiringPi logical pin 3
[code lang=”c”]#include <wiringPi.h>
int main (void)
{
int offset;
offset = 100;
wiringPiSetup () ;
pinMode(0, OUTPUT);
pinMode(2, OUTPUT);
pinMode(3, OUTPUT);
for (;;) // Loop continously
{
digitalWrite (0, HIGH) ;
delay(offset); // delay ‘offset’ miliseconds
digitalWrite(0, LOW); // turn off 0
digitalWrite(2, HIGH); // turn on 2
delay(offset);
digitalWrite(2, LOW); // turn off 2
digitalWrite(3, HIGH); // turn on 3
delay (offset);
digitalWrite(3, LOW); // turn off 3
} // Loop back and start over
return 0 ;
}[/code]
Compile using gcc:
#gcc gpiox.c -o wp gcc wpiox.c -o wp -lwiringPi
The ‘-lwiringPi’ tells the gcc compiler to use the wiring Pi library. Then run using…
#./wp
And watch the LEDs flash…