失眠网 > 玩转树莓派（六）使用C语言通过BCM2835库控制GPIO

玩转树莓派（六）使用C语言通过BCM2835库控制GPIO

时间：2022-09-04 21:20:33

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 CWorkSpacepi@raspberrypi:~ $ cd CWorkSpace/pi@raspberrypi:~/CWorkSpace $ mkdir bcm2835pi@raspberrypi:~/CWorkSpace $ cd bcm2835/

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

pi@raspberrypi:~/CWorkSpace/bcm2835 $ wget /mikem/bcm2835/bcm2835-1.50.tar.gz---02-04 00:08:38-- /mikem/bcm2835/bcm2835-1.50.tar.gz正在解析主机 ()... 192.185.48.187正在连接 ()|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-02-04 00:09:03 (10.5 KB/s) - 已保存 “bcm2835-1.50.tar.gz” [252178/252178])pi@raspberrypi:~/CWorkSpace/bcm2835 $ lsbcm2835-1.50.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 $ lsaclocal.m4 ChangeLogconfig.h.in configureCOPYING doc INSTALLltmain.sh Makefile.in NEWS srcAUTHORSconfig.guess config.sub configure.ac depcomp examples install-sh Makefile.am missingREADME test-driverpi@raspberrypi:~/CWorkSpace/bcm2835/bcm2835-1.50 $ ./configure && makepi@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 18int 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.cpi@raspberrypi:~/CWorkSpace/bcm2835 $ gcc -o gpio_out_bcm2835 gpio_out_bcm2835.c -l bcm2835pi@raspberrypi:~/CWorkSpace/bcm2835 $ ./gpio_out_bcm2835 gpio out: 0gpio out: 1gpio out: 2gpio out: 3gpio out: 4gpio out: 5gpio out: 6gpio out: 7gpio out: 8gpio out: 9gpio 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

//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