android gpio开发脉宽 android gpio控制

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云端小悟空 2023-11-04 20:24:49

文章标签 android gpio开发脉宽 java 引脚 System 文章分类 Android 移动开发

在嵌入式设备中对GPIO的操作是最基本的操作。一般的做法是写一个单独驱动程序，网上大多数的例子都是这样的。其实linux下面有一个通用的GPIO操作接口，那就是我要介绍的 “/sys/class/gpio” 方式。
首先，看看系统中有没有“/sys/class/gpio”这个文件夹。如果没有请在编译内核的时候加入 Device Drivers —> GPIO Support —> /sys/class/gpio/… (sysfs interface)。

/sys/class/gpio 的使用说明：  

01 gpio_operation 通过/sys/文件接口操作IO端口 GPIO到文件系统的映射  

02 * 控制GPIO的目录位于/sys/class/gpio  

03 * /sys/class/gpio/export文件用于通知系统需要导出控制的GPIO引脚编号  

04 * /sys/class/gpio/unexport 用于通知系统取消导出  

05 * /sys/class/gpio/gpiochipX目录保存系统中GPIO寄存器的信息，包括每个寄存器控制引脚的起始编号        base，寄存器名称，引脚总数 导出一个引脚的操作步骤  

06 * 首先计算此引脚编号，引脚编号 = 控制引脚的寄存器基数 + 控制引脚寄存器位数  

07 * 向/sys/class/gpio/export写入此编号，比如12号引脚，在shell中可以通过以下命令实现，  

echo 12 > /sys/class/gpio/export  

  命令成功后生成/sys/class/gpio/gpio12目录，如果没有出现相应的目录，说明此引脚不可导出：  

08    

09 * direction文件，定义输入输入方向，可以通过下面命令定义为输出  

10   echo out > /sys/class/gpio/gpio12/direction  

11 * direction接受的参数：in, out, high, low。high/low同时设置方向为输出，  

    并将value设置为相应的1/0。  

12 * value文件是端口的数值，为1或0.  

13   echo 1 >/sys/class/gpio/gpio12/value  

下面在2440下进行一下测试  

1.取得GPIO信息，在终端中敲入以下命令  

1 $ cd /sys/class/gpio  

2 $ for i in gpiochip* ; do echo `cat $i/label`: `cat $i/base` ; done  

终端中显示如下  

1 GPIOA: 0  

2 GPIOE: 128  

3 GPIOF: 160  

4 GPIOG: 192  

5 GPIOH: 224  

6 GPIOB: 32  

7 GPIOC: 64  

8 GPIOD: 96  

2.计算GPIO号码  

我们把GPE11用来控制LED。  

GPE0的头是128，GPE11 就是128+11 = 139.  

1 $ echo 139 > /sys/class/gpio/export  

ls 一下看看有没有 gpio139 这个目录  

3.GPIO控制测试。  

控制LED所以是输出。  

所以我们应该执行  

1 $ echo out > /sys/class/gpio/gpio139/direction  

之后就可以进行输出设置了。  
1 $ echo 1 > /sys/class/gpio/gpio139/value


==========================================================

GPIO.java
============================GPIO.java=================================
 package com.test.gpio;
 
 import java.io.DataOutputStream;
 import java.io.IOException;
 
 public class GPIO {
 
/**


private static int num, gpio_number;
private static String gpio_num = null;
private static String exportPath;
private static String directionPath;
private static String valuePath;
static Process process = null;
static DataOutputStream dos = null;
public static int gpio_crtl(String gpio, String direction, int level){
if(gpio.length() != 4){
System.out.println("input gpio error!");
return 0;
};
gpio_num = gpio.substring(2, 4); //从String gpio（如PC20）中提取出String 20；      
num = Integer.parseInt(gpio_num);//将String 20转化为int 20；
System.out.println("num:"+num+"\n");
if((gpio.indexOf("pa") >= 0) || (gpio.indexOf("PA") >= 0)){
gpio_number = num; 
}else if((gpio.indexOf("pb") >= 0) || (gpio.indexOf("PB") >= 0)){
gpio_number = num + 24; 
}else if((gpio.indexOf("pc") >= 0) || (gpio.indexOf("PC") >= 0)){
gpio_number = num + 54; 
}else if((gpio.indexOf("pd") >= 0) || (gpio.indexOf("PD") >= 0)){
gpio_number = num + 85; 
}else if((gpio.indexOf("pe") >= 0) || (gpio.indexOf("PE") >= 0)){
gpio_number = num + 119; 
}else if((gpio.indexOf("pf") >= 0) || (gpio.indexOf("PF") >= 0)){
gpio_number = num + 137; 
}else if((gpio.indexOf("pg") >= 0) || (gpio.indexOf("PG") >= 0)){
gpio_number = num + 149; 
}else if((gpio.indexOf("ph") >= 0) || (gpio.indexOf("PH") >= 0)){
gpio_number = num + 167; 
}else if((gpio.indexOf("pi") >= 0) || (gpio.indexOf("PI") >= 0)){
gpio_number = num + 201; 
}
exportPath = "echo " + gpio_number + " > /sys/class/gpio/export";
directionPath = "echo out > " + " /sys/class/gpio/gpio" + gpio_number + "/direction";
valuePath ="echo " + level + " > /sys/class/gpio/gpio" + gpio_number + "/value";
System.out.printf(exportPath + "\n" + directionPath + "\n" + valuePath + "\n");
try {
process = Runtime.getRuntime().exec("su");
dos = new DataOutputStream(process.getOutputStream());
dos.writeBytes(exportPath+"\n"); 
dos.flush(); 
dos.writeBytes(directionPath+"\n");
dos.flush();
dos.writeBytes(valuePath +"\n");
dos.flush();
dos.close();
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
return 0; 
}
 
 }
==========================GPIO.java end===============================
LED.java
============================LED.java=================================
 package com.test.gpio;
 
 import java.io.DataOutputStream;
 import java.io.IOException;
 
 public class LED {
static Process process = null;
public static void setLed(){
DataOutputStream dos = null;
try {
process = Runtime.getRuntime().exec("su");
dos = new DataOutputStream(process.getOutputStream());
dos.writeBytes("echo 74 > /sys/class/gpio/export"+"\n");
dos.flush(); 
//设置引脚功能为输出
dos.writeBytes("echo out > /sys/class/gpio/gpio74/direction"+"\n");
dos.flush();
dos.close();
System.out.println("echo 74 > /sys/class/gpio/export"+"echo out > /sys/class/gpio/gpio74/direction");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} 
}

public static void cmdLedOff() {
// TODO Auto-generated method stub
DataOutputStream dos = null;

try {
process = Runtime.getRuntime().exec("su");
dos = new DataOutputStream(process.getOutputStream());
dos.writeBytes("echo 0 > /sys/class/gpio/gpio74/value"+"\n");

dos.flush();
dos.close();
System.out.println("echo 0 > /sys/class/gpio/gpio74/value");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} 
}

public static void cmdLedOn() {
// TODO Auto-generated method stub
DataOutputStream dos = null;


try {
process = Runtime.getRuntime().exec("su");
dos = new DataOutputStream(process.getOutputStream());
dos.writeBytes("echo 1 > /sys/class/gpio/gpio74/value"+"\n");

dos.flush();
dos.close();
System.out.println("echo 1 > /sys/class/gpio/gpio74/value");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} 
}

public static void ledFlash() {
// TODO Auto-generated method stub

while (true) {
cmdLedOn();
try {
Thread.sleep(500);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
cmdLedOff();
try {
Thread.sleep(500);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} 

}

 }
==============================LED.java  end=============================
MainActivity.java
==============================MainActivity.java===========================
 package com.test.gpio;
 
 import android.os.Bundle;
 import android.app.Activity;
 import android.view.View;
 import android.widget.Button;
 import android.widget.TextView;
 
 public  class MainActivity extends Activity implements View.OnClickListener{
TextView gpio_name;
TextView direction;
TextView  value;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
gpio_name = (TextView) findViewById(R.id.editText1);
direction = (TextView) findViewById(R.id.editText2);
value = (TextView) findViewById(R.id.editText3); 
Button set = (Button)findViewById(R.id.button1);
Button led_on = (Button)findViewById(R.id.button2);
Button led_off = (Button)findViewById(R.id.button3);
Button led_flash = (Button)findViewById(R.id.button4);
LED.setLed();
set.setOnClickListener(this);
led_on.setOnClickListener(this);
led_off.setOnClickListener(this);
led_flash.setOnClickListener(this);
}
public void onClick(View v) {
switch(v.getId()){
case R.id.button1:
// TODO Auto-generated method stub
System.out.println("gpio crtl");
String gp = gpio_name.getText().toString();
String dir = direction.getText().toString();
int val = Integer.valueOf(value.getText().toString());
GPIO.gpio_crtl(gp, dir, val);
break;
case R.id.button2:
System.out.println("led on");
LED.cmdLedOn();
break;
case R.id.button3:
System.out.println("led off");
LED.cmdLedOff();
break;
case R.id.button4:
System.out.println("led flash");
LED.ledFlash();
break;
default:
System.out.println("no opreate!");
break;
} 
} 
 }
=============================MainActivity.java end==========================
gpio_crtl，但无法实现。请大神指点，为什么没权限。即使已经remount的系统仍无法操作：
gpio_crtl============================
 /*******gpio******
 * <for i in gpiochip* ; do echo `cat $i/label`: `cat $i/base` ; done>
 * Allwinner A20 PAD
 * Vstarcam wangjian 2014.07.10
 * GPA: 0
 * GPE: 119
 * GPF: 137
 * GPG: 149
 * GPH: 167
 * GPI: 201
 * axp_pin: 229
 * GPB: 24
 * GPC: 54
 * GPD: 85
 *******************/
 #include<stdlib.h>
 #include <ctype.h>
 #include <stdio.h>
 #include <errno.h>
 
 
 int gpio_crtl(char *gpio, char *direction, int level)
 {
int num, gpio_number, status;
char *gp, *name = NULL;
char *exportPath = NULL;
char *directionPath = NULL;
char *valuePath = NULL;
char *gpio_str = NULL;

if(gpio == NULL || direction == NULL)
return -1;
if(strncpy(gp, gpio, 2) == NULL)//从输入字符串GPIO（如PC20）中提取出字符串“PC”
return -1;
if(strncpy(name, const gpio[2], 2) == NULL)//从输入字符串GPIO（如PC20）中提取出字符串“20”
return -1;
gpio_number = atoi(name);//将字符串“20”转化为整数型
switch(gp){
case ("PA" || "pa"):
num = gpio_number;
break;
case ("PB" || "pb"):
num = gpio_number + 24;
break;
case ("PC" || "pc"):
num = gpio_number + 54;
break;
case ("PD" || "pd"):
num = gpio_number + 85;
break;
case ("PE" || "pe"):
num = gpio_number + 119;
break;
case ("PF" || "pf"):
num = gpio_number + 137;
break;
case ("PG" || "pg"):
num = gpio_number + 149;
break;
case ("PH" || "ph"):
num = gpio_number + 167;
break;
case ("PI" || "pi"):
num = gpio_number + 201;
break;
default:
return -1;
}
itoa(num, gpio_str, 10);
   sprintf(exportPath, "echo %d > /sys/class/gpio/export ", num);
   status = system(exportPath);
   if(status == -1)
 return -1;
   if (!WIFEXITED(status)){//子进程的状态检测
  printf("exportPath exit illegal![%d]/n", errno) ;

   }
   sprintf(directionPath, "echo %s > /sys/class/gpio/%s/direction",direction ,strcat("gpio",gpio_str));
   status = system(directionPath);
   if(status == -1)
 return -1;
   if (!WIFEXITED(status)){
  printf("directionPath

   }
   sprintf(valuePath, "echo %d > /sys/class/gpio/%s/value",level ,strcat("gpio",gpio_str));
   status = system(valuePath);
   if(status == -1)
 return -1;
   if (!WIFEXITED(status)){
  printf("valuePath

   }
 }

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