【Qzone】把喜欢的事做到极致 Kernel->JNI->Application_duplicate declaration of type' at token-优快云博客

本文链接：https://blog.youkuaiyun.com/devwang_com/article/details/52644251

本文介绍如何在Android应用中通过JNI调用C语言函数控制PWM。包括编写Android应用界面、JNI C语言文件、Android.mk配置文件等内容。

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2015-4-1 22:49

ANDROID 应用控制 PWM

从硬件到软件
从C语言到JAVA语言

中间没有涉及HAL和Framework

GEC210 S5PV210
20150401 为什么骗我？

1st
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Kernel
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------

* linux/drivers/char/gec210_pwm.c

* This program is free software; you can redistribute it and/or modify

* it under the terms of the GNU General Public License version 2 as

* published by the Free Software Foundation.

#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/init.h>

#include <linux/platform_device.h>

#include <linux/fb.h>

#include <linux/backlight.h>

#include <linux/err.h>

#include <linux/pwm.h>

#include <linux/slab.h>

#include <linux/miscdevice.h>

#include <linux/delay.h>

#include <mach/gpio.h>

#include <mach/regs-gpio.h>

#include <plat/gpio-cfg.h>

#define DEVICE_NAME "pwm"

#define PWM_IOCTL_SET_FREQ 1

#define PWM_IOCTL_STOP 0

#define NS_IN_1HZ (1000000000UL)

#define BUZZER_PWM_ID 0

#define BUZZER_PMW_GPIO S5PV210_GPD0(0)

static struct pwm_device *pwm4buzzer;

static struct semaphore lock;

static void pwm_set_freq(unsigned long freq) {

int period_ns = NS_IN_1HZ / freq;

pwm_config(pwm4buzzer, period_ns / 2, period_ns);

pwm_enable(pwm4buzzer);

}

static void pwm_stop(void) {

pwm_config(pwm4buzzer, 0, NS_IN_1HZ / 100);

pwm_disable(pwm4buzzer);

}

static int gec210_pwm_open(struct inode *inode, struct file *file) {

if (!down_trylock(&lock))

return 0;

else

return -EBUSY;

}

static int gec210_pwm_close(struct inode *inode, struct file *file) {

up(&lock);

return 0;

}

static long gec210_pwm_ioctl(struct file *filep, unsigned int cmd,

unsigned long arg)

{

switch (cmd) {

case PWM_IOCTL_SET_FREQ:

if (arg == 0)

return -EINVAL;

pwm_set_freq(arg);

break;

case PWM_IOCTL_STOP:

default:

pwm_stop();

break;

}

return 0;

}

static struct file_operations gec210_pwm_ops = {

.owner = THIS_MODULE,

.open = gec210_pwm_open,

.release= gec210_pwm_close,

.unlocked_ioctl= gec210_pwm_ioctl,

};

static struct miscdevice gec210_misc_dev = {

.minor = MISC_DYNAMIC_MINOR,

.name = DEVICE_NAME,

.fops = &gec210_pwm_ops,

};

static int __init gec210_pwm_dev_init(void) {

int ret;

ret = gpio_request(BUZZER_PMW_GPIO, DEVICE_NAME);

if (ret) {

printk("request GPIO %d for pwm failed\n", BUZZER_PMW_GPIO);

return ret;

}

gpio_set_value(BUZZER_PMW_GPIO, 0);

s3c_gpio_cfgpin(BUZZER_PMW_GPIO, S3C_GPIO_OUTPUT);

gpio_set_value(BUZZER_PMW_GPIO, 0);

pwm4buzzer = pwm_request(BUZZER_PWM_ID, DEVICE_NAME)

if (IS_ERR(pwm4buzzer)) {

printk("request pwm %d for %s failed\n", BUZZER_PWM_ID, DEVICE_NAME);

return -ENODEV;

}

pwm_stop();

gpio_set_value(BUZZER_PMW_GPIO, 0);

s3c_gpio_cfgpin(BUZZER_PMW_GPIO, S3C_GPIO_SFN(2));

gpio_free(BUZZER_PMW_GPIO);

gpio_set_value(BUZZER_PMW_GPIO, 0);

init_MUTEX(&lock);

ret = misc_register(&gec210_misc_dev);

printk(DEVICE_NAME "\tinitialized\n");

return ret;

}

static void __exit gec210_pwm_dev_exit(void) {

pwm_stop();

misc_deregister(&gec210_misc_dev);

}

module_init(gec210_pwm_dev_init);

module_exit(gec210_pwm_dev_exit);

MODULE_LICENSE("GPL");

MODULE_AUTHOR("GEC");【资料来自班主任周老师的光盘】

MODULE_DESCRIPTION("S5PV210 PWM Driver");

------------------------------------------------------------------------------------------------------------------------------------------------------------------------
/Kernel
------------------------------------------------------------------------------------------------------------------------------------------------------------------------

2nd

------------------------------------------------------------------------------------------------------------------------------------------------------------------------
JNI
------------------------------------------------------------------------------------------------------------------------------------------------------------------------

#include <jni.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <utils/Log.h>

#define LOG_NDEBUG 0

#define LOG_TAG "pwm"

int fd=-1;

/ *

*此方法为上述Java文件openPwmDev方法的实现体

*native方法代表此方法实现体在C组件动态库完成

JNIEXPORT void JNICALL Java_com_gec_pwmjnitest_activity_PwmJniTestActivity_openPwmDev(JNIEnv * env, jobject object)

{

LOGE("Java_com_gec_pwmjnitest_activity_PwmJniTestActivity_openPwmDev\n");

//打开PWM设备节点

fd=open("/dev/pwm",O_RDWR);

}

*freq变量就是从Java层传入的频率

*通过ioctl调用驱动控制pwm频率

JNIEXPORT void JNICALL Java_com_gec_pwmjnitest_activity_PwmJniTestActivity_opPwm(JNIEnv * env, jobject object,jint op,jlong freq)

{

LOGE("Java_com_gec_pwmjnitest_activity_PwmJniTestActivity_opPwm\n");

ioctl(fd, op , freq );

}

JNIEXPORT void JNICALL Java_com_gec_pwmjnitest_activity_PwmJniTestActivity_closePwmDev(JNIEnv * env, jobject object)

{

LOGE("Java_com_gec_pwmjnitest_activity_PwmJniTestActivity_closePwmDev\n");

//关闭PWM设备节点

close(fd);

}

------------------------------------------------------------------------------------------------------------------------------------------------------------------------
/JNI
------------------------------------------------------------------------------------------------------------------------------------------------------------------------

3rd

------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Application
------------------------------------------------------------------------------------------------------------------------------------------------------------------------

package com.gec.pwmjnitest.activity;

import android.app.Activity;

import android.os.Bundle;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.EditText;

public class PwmJniTestActivity extends Activity {

/** Called when the activity is first created. */

private EditText freId;

private Button btnStart,btnStop;

/ *

*静态加载C组件动态库（动态库名称是libpwmtest.so）

*注意动态库名称不是pwmtest.so，必须要在pwmtest前面加上lib

static

{

System.loadLibrary("pwmtest");

}

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

openPwnDev();

freId=(EditText)findViewById(R.id.freId);

btnStart=(Button)findViewById(R.id.btn_start_id);

btnStop=(Button)findViewById(R.id.btn_stop_id);

btnStart.setOnClickListener(new OnClickListener() {

public void onClick(View v) {

// TODO Auto-generated method stub

String sfreq=freId.getText().toString();

//输入参数频率

opPwm(1,Long.parseLong(sfreq));

}

});

btnStop.setOnClickListener(new OnClickListener() {

public void onClick(View v) {

// TODO Auto-generated method stub

String sfreq=freId.getText().toString();

opPwm(0,Long.parseLong(sfreq));

}

});

}

@Override

protected void onDestroy() {

// TODO Auto-generated method stub

super.onDestroy();

closePwmDev();

}

*声明三个native方法

*native方法代表此方法实现体在C组件动态库完成

*op=1:代表启动蜂鸣器， op=0:代表停止蜂鸣， freq:输入蜂鸣器的频率

public native void openPwmDev();

/ *

*op=1:代表启动蜂鸣器， op=0:代表停止蜂鸣， freq:输入蜂鸣器的频率

public native void opPwm(int op,long freq);

public native void closePwmDev();

}

通过 Eclipse 开发 Android 应用程序界面

编写 JNI 程序的 C 语言文件

编写 Android.mk 文件

编译 Android 程序

本程序原理Android应用层界面开发由JAVA语言实现，然后静态加载C语言组件动

态库， C语言组件动态库必须以JNI框架标准（Java Native Interface (JNI)标准是java

平台的一部分，它允许Java代码和其他语言写的代码进行交互。 JNI 是本地编程

接口，它使得在 Java 虚拟机 (VM) 内部运行的 Java 代码能够与用其它编程语

言(如 C、 C++ 和汇编语言)编写的应用程序和库进行交互操作。），然后在C语言

组件动态库调用PWM驱动程序。

编写 PWMJNITESTACTIVITY.JAVA 源程序代码

工程目录新建 JNI 目录，编写 C 组件动态库 APPPWM.C 文件

根据 JNI1.0 调用规则

C 语言: appPwm.c 文件里面的

openPwmDev ------->Java_com_gec_pwmjnitest_activity_PwmJniTestActivity_openPwmDev

opPwn ------->Java_com_gec_pwmjnitest_activity_PwmJniTestActivity_opPwm

closePwnDev ------> Java_com_gec_pwmjnitest_activity_PwmJniTestActivity_closePwmDev

左边是在 JAVA 类声明的 native 成员方法，右边是 C 语言函数对应成员方法实现体

编写生成 JNI 动态库的配置文件 ANDROID.MK

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_MODULE:=libpwmtest a

LOCAL_SRC_FILES:=appPwm.c b

LOCAL_C_INCLUDES+= \ c

$(JNI_H_INCLUDE)

LOCAL_PRELINK_MODULE := false

LOCAL_MODULE_TAGS:= debug

include $(BUILD_SHARED_LIBRARY) d

其中abcd为注释，下同

a：生成C 动态库名称libpwmtest(JAVA层就是通过加载此库名称来实现互调)

b：编译C文件

c：加载jni库头文件

d：生成libpwmtest动态库，要跟Java静态加载的库名一致

编写应用工程 ANDROID.MK 文件

LOCAL_PATH:= $(call my-dir) a

include $(CLEAR_VARS) b

LOCAL_SRC_FILES := $(call all-subdir-java-files) c

LOCAL_PACKAGE_NAME:= PwmJniTest d

LOCAL_JNI_SHARED_LIBRARIES:= libpwmtest e

include $(BUILD_PACKAGE) f

include $(LOCAL_PATH)/jni/Android.mk g

# Use the folloing include to make our test apk.

include $(call all-makefiles-under,$(LOCAL_PATH)) h

a：一个Android.mk文件首先必须定义好LOCAL_PATH，获得当前目录

b：用来初始化Android.mk文件中” LOCAL_XXX” 的变量

c：编译Java文件

d：生成Android应用apk文件名称

e：生成JNI动态库libpwmtest

f：生成Android应用

g：编译jni目录里面的Android.mk文件

h：编译此工程里面所有的Android.mk文件

PWM 应用编译

将应用工程源代码(PwmJniTest)放到 Android-2.3.1\vendor\samsung\gec210\目录中，先

对整个 Android-2.3.1 系统进行一次完整的编译。编译后按如下流程编译应用程序：

在 Android 源码目录下输入命令

#source build/envsetup.sh （生成的使用环境及环境中的命令）

#lunch 4（选择 full_gec210-eng 开发板）【full_gec210-eng 不知道这个是怎么来的】

#mmm vendor/samsung/gec210/ PwnJniTest（编译当前应用程序）

成功编译后会在 out/target/product/gec210/system/app/目录下生成对应的

PwmJniTest.apk 文件【虽这个不曾尝试但亲测编译过模拟器Goldfish版的确实如此】

仅仅理论木有实践

THE END

114

【Qzone】把喜欢的事做到极致 Kernel->JNI->Application

2015-4-1 22:49

ANDROID 应用控制 PWM 从硬件到软件 从C语言到JAVA语言

中间没有涉及HAL和Framework

GEC210 S5PV210 20150401 为什么骗我？

ANDROID 应用控制 PWM

从硬件到软件
从C语言到JAVA语言

GEC210 S5PV210
20150401 为什么骗我？