如果想要使用树莓派的gpio、iic、spi等外设资源，我们就需要用到树莓派
一、wringpi
wringpi在raspbian系统中都有预装，如果想要重新安装和更新可以执行以下命令：
sudo apt-get install wringpi
sudo apt-get upgrade wiringpi
安装完成后查看wiringpi的版本：
gpio -v
如果安装成功，会打印版本相关的信息：
root@raspberrypi:/share/raspberry/soft# gpio -v
gpio version: 2.50
Copyright (c) 2012-2018 Gordon Henderson
This is free software with ABSOLUTELY NO WARRANTY.
For details type: gpio -warranty
Raspberry Pi Details:
Type: Pi 3B+, Revision: 03, Memory: 1024MB, Maker: Sony
* Device tree is enabled.
*--> Raspberry Pi 3 Model B Plus Rev 1.3
* This Raspberry Pi supports user-level GPIO access.
我们还可以通过命令来查看树莓派的外部引脚：
gpio readall
root@raspberrypi:/share/raspberry# gpio readall
+-----+-----+---------+------+---+---Pi 3B+-+---+------+---------+-----+-----+
| 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 | OUT | 0 | 7 || 8 | 0 | 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 3B+-+---+------+---------+-----+-----+
wringpi之前一直是开源的，但是后来只有用于商业用途才能获得源代码，现在在网上找到的源代码都是比较老的版本了。
官网地址：http://wiringpi.com/
早期源码：[https://github.com/mm1994uestc/WiringPi.git]https://github.com/mm1994uestc/WiringPi.git)
二、bcm2835
和wringpi相比，bcm2835库更加简洁，它只有两个源文件bcm2835.c和bcm2835.h。在使用过程中我们可以选择将其安装到树莓派中来使用，也可以选择直接将两个文件包含到我们的应用代码中。我个人倾向于后者，因为bcm2835库本身就只有两个源文件，添加到应用层代码很简单而且方便查看源码。
bcm2835官网地址：官网地址
bcm2835下载地址：下载地址
安装方法：
tar -zxvf bcm2835-1.68.tar.gz
cd bcm2835-1.68
./configure
make
sudo make check
sudo make install