Dennis Núñez-Fernández

BSc in Electronic Engineering, Universidad Nacional de Ingeniería (UNI)


Controlling GPIO and PWM in C/C++ with WiringPi library on Raspberry Pi

Check the pins of the RPi 3:

$ gpio readall +-----+-----+---------+------+---+---Pi 3---+---+------+---------+-----+-----+ | BCM | wPi | Name | Mode | V | Physical | V | Mode | Name | wPi | BCM | +-----+-----+---------+------+---+----++----+---+------+---------+-----+-----+ | | | 3.3v | | | 1 || 2 | | | 5v | | | | 2 | 8 | SDA.1 | IN | 1 | 3 || 4 | | | 5v | | | | 3 | 9 | SCL.1 | IN | 1 | 5 || 6 | | | 0v | | | | 4 | 7 | GPIO. 7 | IN | 1 | 7 || 8 | 1 | IN | TxD | 15 | 14 | | | | 0v | | | 9 || 10 | 1 | IN | RxD | 16 | 15 | | 17 | 0 | GPIO. 0 | IN | 0 | 11 || 12 | 0 | IN | GPIO. 1 | 1 | 18 | | 27 | 2 | GPIO. 2 | IN | 0 | 13 || 14 | | | 0v | | | | 22 | 3 | GPIO. 3 | IN | 0 | 15 || 16 | 0 | IN | GPIO. 4 | 4 | 23 | | | | 3.3v | | | 17 || 18 | 0 | IN | GPIO. 5 | 5 | 24 | | 10 | 12 | MOSI | IN | 0 | 19 || 20 | | | 0v | | | | 9 | 13 | MISO | IN | 0 | 21 || 22 | 0 | IN | GPIO. 6 | 6 | 25 | | 11 | 14 | SCLK | IN | 0 | 23 || 24 | 1 | IN | CE0 | 10 | 8 | | | | 0v | | | 25 || 26 | 1 | IN | CE1 | 11 | 7 | | 0 | 30 | SDA.0 | IN | 1 | 27 || 28 | 1 | IN | SCL.0 | 31 | 1 | | 5 | 21 | GPIO.21 | IN | 1 | 29 || 30 | | | 0v | | | | 6 | 22 | GPIO.22 | IN | 1 | 31 || 32 | 0 | IN | GPIO.26 | 26 | 12 | | 13 | 23 | GPIO.23 | IN | 0 | 33 || 34 | | | 0v | | | | 19 | 24 | GPIO.24 | IN | 0 | 35 || 36 | 0 | IN | GPIO.27 | 27 | 16 | | 26 | 25 | GPIO.25 | IN | 0 | 37 || 38 | 0 | IN | GPIO.28 | 28 | 20 | | | | 0v | | | 39 || 40 | 0 | IN | GPIO.29 | 29 | 21 | +-----+-----+---------+------+---+----++----+---+------+---------+-----+-----+ | BCM | wPi | Name | Mode | V | Physical | V | Mode | Name | wPi | BCM | +-----+-----+---------+------+---+---Pi 3---+---+------+---------+-----+-----+


Controlling a led in C/C++ with Wiring Pi

Use the next connection for wiring:

Create the file test_led.c or test_led.cpp:

#include <wiringPi.h> #include <stdio.h> #include <stdlib.h> #include <stdint.h> int main(void) { printf("Raspberry Pi wiringPi led test program\n"); if (wiringPiSetup() == -1) exit(1) ; pinMode(0, OUTPUT); int i = 0; for(i = 0;i<10;i++){ digitalWrite(0, HIGH); delay(500); digitalWrite(0, LOW); delay(500); } return 0; }

Compile test_led.c using:

$ gcc -Wall -o test_led test_led.c -lwiringPi

Or compile test_led.cpp using:

$ gcc -Wall -o test_led test_led.cpp -lwiringPi

Execute using:

$ sudo ./test_led

So, the led will start blinking for 10 seconds.


Controlling PWM in C/C++ with Wiring Pi

Use the next connection for wiring:

Create the file test_pwm.c or test_pwm.cpp:

#include <wiringPi.h> #include <stdio.h> #include <stdlib.h> #include <stdint.h> int main(void) { printf("Raspberry Pi wiringPi PWM test program\n"); if (wiringPiSetup() == -1) exit(1) ; pinMode(1, PWM_OUTPUT); pwmSetRange(10); pwmWrite(1, 9) ; //pwmWrite(PIN, VALUE) for(;;){ delay(1); } return 0; }

Compile test_pwm.c using:

$ gcc -Wall -o test_pwm test_pwm.c -lwiringPi

Or compile test_pwm.cpp using:

$ gcc -Wall -o test_pwm test_pwm.cpp -lwiringPi

Execute using:

$ sudo ./test_pwm

So, the intensity of the led will change according the VALUE you choose.