做外贸没有网站/站长seo查询

参考资料

链接: BeagleBone Black使用（一）：狗板简介

链接: 使用Beaglebone Black的IO口

开机

直接用usb连接到电脑上，这是个otg口，虚拟成了网卡：

网口登录：
Debian GNU/Linux 10 beaglebone ttyS0

BeagleBoard.org Debian Buster IoT Image 2020-04-06

Support: http://elinux.org/Beagleboard:BeagleBoneBlack_Debian

default username:password is [debian:temppwd]
默认用户名密码：debian:temppwd

串口登录（串口可以直接荣root登录 root|root）：

led控制

开启

 echo none > /sys/class/leds/beaglebone:green:usr3/trigger && echo 1 > /sys/class/leds/beaglebone:green:usr3/brightness

关闭

 echo none > /sys/class/leds/beaglebone:green:usr3/trigger && echo 0 > /sys/class/leds/beaglebone:green:usr3/brightness

python代码：

#!/usr/bin/python
#//
#	blink.py
#	Blinks one LED wired to P9_15.
#	Wiring:	P9_15 connects to the plus lead of an LED.  The negative lead of the
#			LED goes to a 220 Ohm resistor.  The other lead of the resistor goes
#			to ground.
#	Setup:	
#	See:	
#//
import Adafruit_BBIO.GPIO as GPIO
import timeout = "P9_15"GPIO.setup(out, GPIO.OUT)while True:GPIO.output(out, GPIO.HIGH)time.sleep(0.5)GPIO.output(out, GPIO.LOW)time.sleep(0.5)

c代码：

//	blinkLED.c
//      Blinks the USR3 LED.
//	Wiring:	None
//	Setup:	
//	See:	

#include <stdio.h>
#include <unistd.h>int main() {FILE * trigger = fopen("/sys/class/leds/beaglebone:green:usr3/trigger", "w");FILE * brightness = fopen("/sys/class/leds/beaglebone:green:usr3/brightness", "w");int on = 0;fprintf(trigger, "none\n");while(1) {fprintf(brightness, "%d\n", on);fflush(brightness);if(!on) on = 1;else on = 0;usleep(500000);}
}

//	ring.pru0.c
//      Does the "Ring Test" given here: https://pub.pages.cba.mit.edu/ring/
//	Reads P8_19 and writes it to P9_16 as fast as it can.
//	Wiring:	P9_16 connects to the plus lead of an LED.  The negative lead of the
//			LED goes to a 220 Ohm resistor.  The other lead of the resistor goes
//			to ground (P9_1 or P9_2).
//			Wire P8_19 to P9_16 to produce the 'ring' circuit.
//              A Switch goes to P8_19 and 3.3V  (P9_3 or P9_4).
//	Setup:	config_pin P9_16 pruout and config_pin P8_19 to pruin
//	See:	prugpio.h to see which pins attach to R30
//	PRU:	pru0

#include <stdint.h>
#include <pru_cfg.h>
#include <pru_ctrl.h>
#include <stddef.h>
#include <rsc_types.h>
#include "resource_table_empty.h"
#include "prugpio.h"volatile register unsigned int __R30;
volatile register unsigned int __R31;void main(void) {/* Read GPIO input P9_25 and invert to GPIO output P9_29 */while(1) {if(__R31 & P8_19)__R30 = 0;else__R30 = P9_16;}
}

GPIO输入输出

root@beaglebone:~# cd /sys/class/gpio
root@beaglebone:/sys/class/gpio# ls -l
total 0
--w------- 1 root root 4096 Jan  1 00:00 export
lrwxrwxrwx 1 root root    0 Jan  1 00:00 gpiochip0 -> ../../devices/virtual/gpio/gpiochip0
lrwxrwxrwx 1 root root    0 Jan  1 00:00 gpiochip32 -> ../../devices/virtual/gpio/gpiochip32
lrwxrwxrwx 1 root root    0 Jan  1 00:00 gpiochip64 -> ../../devices/virtual/gpio/gpiochip64
lrwxrwxrwx 1 root root    0 Jan  1 00:00 gpiochip96 -> ../../devices/virtual/gpio/gpiochip96
--w------- 1 root root 4096 Jan  1 00:00 unexport
root@beaglebone:/sys/class/gpio# echo 44 > export
root@beaglebone:/sys/class/gpio# ls -l
total 0
--w------- 1 root root 4096 Jan  1 00:03 export
lrwxrwxrwx 1 root root    0 Jan  1 00:03 gpio44 -> ../../devices/virtual/gpio/gpio44
lrwxrwxrwx 1 root root    0 Jan  1 00:00 gpiochip0 -> ../../devices/virtual/gpio/gpiochip0
lrwxrwxrwx 1 root root    0 Jan  1 00:00 gpiochip32 -> ../../devices/virtual/gpio/gpiochip32
lrwxrwxrwx 1 root root    0 Jan  1 00:00 gpiochip64 -> ../../devices/virtual/gpio/gpiochip64
lrwxrwxrwx 1 root root    0 Jan  1 00:00 gpiochip96 -> ../../devices/virtual/gpio/gpiochip96
--w------- 1 root root 4096 Jan  1 00:00 unexport
root@beaglebone:/sys/class/gpio# cd gpio44
root@beaglebone:/sys/class/gpio/gpio44# ls -l
total 0
-rw-r--r-- 1 root root 4096 Jan  1 00:03 active_low
-rw-r--r-- 1 root root 4096 Jan  1 00:03 direction
-rw-r--r-- 1 root root 4096 Jan  1 00:03 edge
drwxr-xr-x 2 root root    0 Jan  1 00:03 power
lrwxrwxrwx 1 root root    0 Jan  1 00:03 subsystem -> ../../../../class/gpio
-rw-r--r-- 1 root root 4096 Jan  1 00:03 uevent
-rw-r--r-- 1 root root 4096 Jan  1 00:03 value
root@beaglebone:/sys/class/gpio/gpio44# cat direction
in
root@beaglebone:/sys/class/gpio/gpio44# echo out > direction
root@beaglebone:/sys/class/gpio/gpio44# cat direction
out
root@beaglebone:/sys/class/gpio/gpio44# cat value
0
root@beaglebone:/sys/class/gpio/gpio44# echo 1 > value
root@beaglebone:/sys/class/gpio/gpio44# cat value
1
—

解释一下，首先要把某个（本例中是第44个，即P8_12）gpio export一下，变成用户可用的状态，然后目录里就会多出来一个gpio44目录，进入它对相应文件进行读写就可以操作io口了。输入输出是一样的道理。读的话Linux会自动实时更新value文件里的数据，但更新速度有多快暂时还不清楚，高速io操作的话用这种方法感觉不靠谱。不过速度不敏感的话是没问题的。

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <fcntl.h> //define O_WRONLY and O_RDONLY
#define SYSFS_GPIO_DIR "/sys/class/gpio"
#define MAX_BUF 64void main()
{int fd, len;char buf[MAX_BUF];char ch;int i;//export gpio44fd = open(SYSFS_GPIO_DIR "/export", O_WRONLY);len = snprintf(buf,sizeof(buf),"44");write(fd,buf,len);close(fd);//set directionsnprintf(buf,sizeof(buf),SYSFS_GPIO_DIR"/gpio44/direction");fd = open(buf, O_WRONLY);write(fd, "in", 3);close(fd);//read and print value 10 timesfor(i=0;i<10;i++){snprintf(buf,sizeof(buf),SYSFS_GPIO_DIR"/gpio44/value");fd = open(buf, O_RDONLY);read(fd,&ch,1);printf("%c\n",ch);close(fd);usleep(1000000);}
}

查看引脚输入状态（空闲高电平3.3V输出1, 接GND输出 0）

root@beaglebone:/sys/class/gpio# cd gpio44/
root@beaglebone:/sys/class/gpio/gpio44# ls
active_low  device  direction  edge  label  power  subsystem  uevent  value
root@beaglebone:/sys/class/gpio/gpio44# cat direction
in
root@beaglebone:/sys/class/gpio/gpio44#
root@beaglebone:/sys/class/gpio/gpio44#
root@beaglebone:/sys/class/gpio/gpio44#
root@beaglebone:/sys/class/gpio/gpio44#
root@beaglebone:/sys/class/gpio/gpio44# echo out > direction
root@beaglebone:/sys/class/gpio/gpio44#
root@beaglebone:/sys/class/gpio/gpio44# cat direction
out
root@beaglebone:/sys/class/gpio/gpio44# cat value
0
root@beaglebone:/sys/class/gpio/gpio44#
root@beaglebone:/sys/class/gpio/gpio44# echo 1 > value
root@beaglebone:/sys/class/gpio/gpio44# echo 0 > value
root@beaglebone:/sys/class/gpio/gpio44# cd ../gpio6
gpio60/ gpio61/ gpio62/ gpio63/ gpio65/ gpio66/ gpio67/ gpio68/ gpio69/
root@beaglebone:/sys/class/gpio/gpio44# cd ../gpio68/
root@beaglebone:/sys/class/gpio/gpio68# cat value
1
root@beaglebone:/sys/class/gpio/gpio68# cat direction
in
root@beaglebone:/sys/class/gpio/gpio68# cat direction
in
root@beaglebone:/sys/class/gpio/gpio68# cat value
0
root@beaglebone:/sys/class/gpio/gpio68# cat value
1