玩转树莓派（六）使用C语言通过BCM2835库控制GPIO

喜欢ヅ旅行 2022-10-27 12:10 301阅读 0赞

# 玩转树莓派（六）使用C语言 通过BCM2835库控制GPIO #

### 目录 ###

*  玩转树莓派（六）使用C语言 通过BCM2835库控制GPIO
 *   *  一、创建环境
     *  二、编写代码
     *  三、编译运行
     *  四、查看效果
     *  五、BCM2835库简单介绍
     *  六、漂亮的Ending

## 一、创建环境 ##

因为BCM2835 Library在Raspberry Pi OS系统中没有内置，所以需要用户自行下载。

*  新建CWorkSpace文件夹
 *  新建bcm2835文件夹

pi@raspberrypi:~ $ mkdir CWorkSpace
    pi@raspberrypi:~ $ cd CWorkSpace/
    pi@raspberrypi:~/CWorkSpace $ mkdir bcm2835
    pi@raspberrypi:~/CWorkSpace $ cd bcm2835/

*  下载bcm2835-1.50.tar.gz（BCM2835 Library）

pi@raspberrypi:~/CWorkSpace/bcm2835 $ wget http://www.airspayce.com/mikem/bcm2835/bcm2835-1.50.tar.gz
    --2021-02-04 00:08:38--  http://www.airspayce.com/mikem/bcm2835/bcm2835-1.50.tar.gz
    正在解析主机 www.airspayce.com (www.airspayce.com)... 192.185.48.187
    正在连接 www.airspayce.com (www.airspayce.com)|192.185.48.187|:80... 已连接。
    已发出 HTTP 请求，正在等待回应... 200 OK
    长度：252178 (246K) [application/x-gzip]
    正在保存至: “bcm2835-1.50.tar.gz”
    
    bcm2835-1.50.tar.gz                  100%[=====================================================================>] 246.27K  7.96KB/s  用时 23s     
    
    2021-02-04 00:09:03 (10.5 KB/s) - 已保存 “bcm2835-1.50.tar.gz” [252178/252178])
    
    pi@raspberrypi:~/CWorkSpace/bcm2835 $ ls
    bcm2835-1.50.tar.gz

*  解压缩bcm2835-1.50.tar.gz

pi@raspberrypi:~/CWorkSpace/bcm2835 $ tar -zxvf bcm2835-1.50.tar.gz

*  配置、编译、安装

pi@raspberrypi:~/CWorkSpace/bcm2835 $ cd bcm2835-1.50/
    pi@raspberrypi:~/CWorkSpace/bcm2835/bcm2835-1.50 $ ls
    aclocal.m4  ChangeLog     config.h.in  configure     COPYING  doc       INSTALL     ltmain.sh    Makefile.in  NEWS    src
    AUTHORS     config.guess  config.sub   configure.ac  depcomp  examples  install-sh  Makefile.am  missing      README  test-driver
    pi@raspberrypi:~/CWorkSpace/bcm2835/bcm2835-1.50 $ ./configure && make
    pi@raspberrypi:~/CWorkSpace/bcm2835/bcm2835-1.50 $ sudo make install

## 二、编写代码 ##

*  编辑gpio\_out\_bcm2835.c

#include <bcm2835.h>
    #include <stdio.h>
    
    #define PIN 18
    int main(void)
    { 
    	int i=0;
    	
    	if (!bcm2835_init())
    		return 1;
    	
    	bcm2835_gpio_fsel(PIN, BCM2835_GPIO_FSEL_OUTP);
    	for(i=0;i<10;i++)
    	{ 
    		printf("gpio out: %d\r\n", i);
    		bcm2835_gpio_write(PIN, i%2);
    		delay(3000);
    	}
    	bcm2835_close();
    	printf("gpio out end\r\n");
    	return 0;
    }

## 三、编译运行 ##

*  编译，编译时要连接bcm2835的库
 *  运行

pi@raspberrypi:~/CWorkSpace/bcm2835 $ vim gpio_out_bcm2835.c
    pi@raspberrypi:~/CWorkSpace/bcm2835 $ gcc -o gpio_out_bcm2835 gpio_out_bcm2835.c -l bcm2835
    pi@raspberrypi:~/CWorkSpace/bcm2835 $ ./gpio_out_bcm2835 
    gpio out: 0
    gpio out: 1
    gpio out: 2
    gpio out: 3
    gpio out: 4
    gpio out: 5
    gpio out: 6
    gpio out: 7
    gpio out: 8
    gpio out: 9
    gpio out end

## 四、查看效果 ##

用万用表量下BCM编号18的GPIO.1的引脚，可以发现其间隔3s的高低电平变换了10次。

pi@raspberrypi:~/PythonWorkSpace $ 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 |   IN | 1 |  7 || 8  | 0 | IN   | TxD     | 15  | 14  |
     |     |     |      0v |      |   |  9 || 10 | 1 | IN   | RxD     | 16  | 15  |
     |  17 |   0 | GPIO. 0 |   IN | 0 | 11 || 12 | 1 | OUT  | 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--+---+------+---------+-----+-----+

## 五、BCM2835库简单介绍 ##

<table> 
 <thead> 
  <tr> 
   <th>函数</th> 
   <th align="left">int bcm2835_init(void)</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>说明</td> 
   <td align="left">Initialise this library.</td> 
  </tr> 
  <tr> 
   <td>返回</td> 
   <td align="left">1：成功；0：失败</td> 
  </tr> 
 </tbody> 
</table>

<table> 
 <thead> 
  <tr> 
   <th>函数</th> 
   <th align="left">int bcm2835_close(void)</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>说明</td> 
   <td align="left">Close this library and deallocate everything</td> 
  </tr> 
  <tr> 
   <td>返回</td> 
   <td align="left">1：成功；0：失败</td> 
  </tr> 
 </tbody> 
</table>

<table> 
 <thead> 
  <tr> 
   <th>函数</th> 
   <th align="left">void bcm2835_gpio_fsel(uint8_t pin, uint8_t mode)</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>说明</td> 
   <td align="left">Each control register has 10 sets of 3 bits per GPIO pin</td> 
  </tr> 
  <tr> 
   <td>输入</td> 
   <td align="left">pin：BCM系统的引脚编号</td> 
  </tr> 
  <tr> 
   <td>——</td> 
   <td align="left">mode： Each control register has 10 sets of 3 bits per GPIO pin（如下）</td> 
  </tr> 
 </tbody> 
</table>

// 000 = GPIO Pin X is an input
    // 001 = GPIO Pin X is an output
    // 100 = GPIO Pin X takes alternate function 0
    // 101 = GPIO Pin X takes alternate function 1
    // 110 = GPIO Pin X takes alternate function 2
    // 111 = GPIO Pin X takes alternate function 3
    // 011 = GPIO Pin X takes alternate function 4
    // 010 = GPIO Pin X takes alternate function 5

<table> 
 <thead> 
  <tr> 
   <th>函数</th> 
   <th align="left">void bcm2835_gpio_write(uint8_t pin, uint8_t on)</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>说明</td> 
   <td align="left">Set the state of an output</td> 
  </tr> 
  <tr> 
   <td>输入</td> 
   <td align="left">pin：BCM系统的引脚编号</td> 
  </tr> 
  <tr> 
   <td>——</td> 
   <td align="left">on： 1：高电平；0：低电平</td> 
  </tr> 
 </tbody> 
</table>

## 六、漂亮的Ending ##

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