====== WiringPi ======

===== Introduction =====

WiringPi is a C++ library for Raspberry Pi, we port it to Khadas SBC, With this library you can use many of the functionalities provided by the GPIO header: digital pins, SPI, I2C, UART, etc.

===== WiringPi Instructions =====

There are two methods here, via command line or C program.

==== Get Pin Info ====

Run ''gpio readall'', and it will print a table about the status of all GPIO pins.

''GPIO'' –> GPIO native number \\
''wPi'' –> WiringPi number \\
''Mode'' –> GPIO Mode ,''ALT'' mean that this pin defined as a special function \\
''V'' –> 1 - HIGH, 0 - LOW \\
''PU/PD'' –> ''PU'' - pull up, ''PD'' - pull down, ''DSBLD'' - disabled

==== Using via Command Line ====

Here’s an example of controlling wpi number 1.

  * Set GPIO mode to output 
```shell
$ gpio mode 1 out
```
  * Set output low level
```shell
$ gpio write 1 0
```
  * Set output high level
```shell
$ gpio write 1 1
```

==== Using via C Program ====

The test program changes the level value every 5S.

```c wiringpi.c
// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
/*
 * Copyright (c) 2022 Wesion Technology Co., Ltd.
 *
 * Author: Yan <yan-wyb@foxmail.com> 
 *
 */

#include <stdio.h>
#include <wiringPi.h>

const int gpio_pin = 1;

int main()
{
    if(-1 == wiringPiSetup()){
        printf("set up error");
        exit(1);
    }

    pinMode(gpio_pin,OUTPUT);

    while(1){
        digitalWrite(gpio_pin,HIGH);
        printf("wPi Pin %d now is GIGH\n",gpio_pin);
        delay(5000);
        digitalWrite(gpio_pin,LOW);
        printf("wPi Pin %d now is LOW\n",gpio_pin);
        delay(5000);
    }

    exit(0);
}
```

Compile

```shell
$ gcc -o wiringpi wiringpi.c -lwiringPi -lpthread -lrt -lm -lcrypt
```

Run
```shell
sudo ./wiringpi
wPi Pin 1 now is GIGH
wPi Pin 1 now is LOW
wPi Pin 1 now is GIGH
wPi Pin 1 now is LOW
```
You can use ''gpio read 1'' to observe the pin level changes.

==== Special Pin Functions ====

Special pin functions of wiringpi include ''SPI'',''I2C'',''ADC'',''SoftPWM''.
Please refer to the [[/products/sbc/common/applications/gpio/40pin-header|40-Pin Header]] for the corresponding physical pins.