Question

我正在尝试使用下面的.c文件在Android（rooted device）中打开端口。不幸的是，它给了我错误tcsetattr() failed这是登录我的文件（见下面的代码）。我似乎没有解决问题任何帮助表示赞赏。

注意：targetSdkVersion 17

此外，我在dev / ttyS4上测试了canRead()和canWrite()   返回true

#include <termios.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <jni.h>

#include "serial_port.h"

#include "android/log.h"
static const char *TAG="serial_port";
#define LOGI(fmt, args...) __android_log_print(ANDROID_LOG_INFO,  TAG, fmt, ##args)
#define LOGD(fmt, args...) __android_log_print(ANDROID_LOG_DEBUG, TAG, fmt, ##args)
#define LOGE(fmt, args...) __android_log_print(ANDROID_LOG_ERROR, TAG, fmt, ##args)

static speed_t getBaudrate(jint baudrate)
{
    switch(baudrate) {
        case 0: return B0;
        case 50: return B50;
        case 75: return B75;
        case 110: return B110;
        case 134: return B134;
        case 150: return B150;
        case 200: return B200;
        case 300: return B300;
        case 600: return B600;
        case 1200: return B1200;
        case 1800: return B1800;
        case 2400: return B2400;
        case 4800: return B4800;
        case 9600: return B9600;
        case 19200: return B19200;
        case 38400: return B38400;
        case 57600: return B57600;
        case 115200: return B115200;
        case 230400: return B230400;
        case 460800: return B460800;
        case 500000: return B500000;
        case 576000: return B576000;
        case 921600: return B921600;
        case 1000000: return B1000000;
        case 1152000: return B1152000;
        case 1500000: return B1500000;
        case 2000000: return B2000000;
        case 2500000: return B2500000;
        case 3000000: return B3000000;
        case 3500000: return B3500000;
        case 4000000: return B4000000;
        default: return -1;
    }
}

/*
 * Class:     android_serialport_SerialPort
 * Method:    open
 * Signature: (Ljava/lang/String;II)Ljava/io/FileDescriptor;
 */
JNIEXPORT jobject JNICALL Java_com_geotek_invent_rodinbell_port_SerialPort_open
        (JNIEnv *env, jclass thiz, jstring path, jint baudrate, jint flags)
{
    int fd;
    speed_t speed;
    jobject mFileDescriptor;

    /* Check arguments */
    {
        speed = getBaudrate(baudrate);
        if (speed == -1) {
            /* TODO: throw an exception */
            LOGE("Invalid baudrate");
            return NULL;
        }
    }

    /* Opening device */
    {
        jboolean iscopy;
        const char *path_utf = (*env)->GetStringUTFChars(env, path, &iscopy);
        LOGD("Opening serial port %s with flags 0x%x", path_utf, O_RDWR | flags);
        fd = open(path_utf, O_RDWR | flags);
        LOGD("open() fd = %d", fd);
        (*env)->ReleaseStringUTFChars(env, path, path_utf);
        if (fd == -1)
        {
            /* Throw an exception */
            LOGE("Cannot open port");
            /* TODO: throw an exception */
            return NULL;
        }
    }

    /* Configure device */
    {
        struct termios cfg;
        LOGD("Configuring serial port");
        if (tcgetattr(fd, &cfg))
        {
            LOGE("tcgetattr() failed");
            close(fd);
            /* TODO: throw an exception */
            return NULL;
        }

        cfmakeraw(&cfg);
        cfsetispeed(&cfg, speed);
        cfsetospeed(&cfg, speed);

        if (tcsetattr(fd, TCSANOW, &cfg))
        {
            LOGE("tcsetattr() failed");
            close(fd);
            /* TODO: throw an exception */
            return NULL;
        }
    }

    /* Create a corresponding file descriptor */
    {
        jclass cFileDescriptor = (*env)->FindClass(env, "java/io/FileDescriptor");
        jmethodID iFileDescriptor = (*env)->GetMethodID(env, cFileDescriptor, "<init>", "()V");
        jfieldID descriptorID = (*env)->GetFieldID(env, cFileDescriptor, "descriptor", "I");
        mFileDescriptor = (*env)->NewObject(env, cFileDescriptor, iFileDescriptor);
        (*env)->SetIntField(env, mFileDescriptor, descriptorID, (jint)fd);
    }

    return mFileDescriptor;
}

/*
 * Class:     cedric_serial_SerialPort
 * Method:    close
 * Signature: ()V
 */
JNIEXPORT void JNICALL Java_com_geotek_invent_rodinbell_port_SerialPort_close
        (JNIEnv *env, jobject thiz)
{
    jclass SerialPortClass = (*env)->GetObjectClass(env, thiz);
    jclass FileDescriptorClass = (*env)->FindClass(env, "java/io/FileDescriptor");

    jfieldID mFdID = (*env)->GetFieldID(env, SerialPortClass, "mFd", "Ljava/io/FileDescriptor;");
    jfieldID descriptorID = (*env)->GetFieldID(env, FileDescriptorClass, "descriptor", "I");

    jobject mFd = (*env)->GetObjectField(env, thiz, mFdID);
    jint descriptor = (*env)->GetIntField(env, mFd, descriptorID);

    LOGD("close(fd = %d)", descriptor);
    close(descriptor);
}

Answer 1

再次感谢Android版本:(我已经浪费了相当长的时间才能找到这篇文章http://m.blog.csdn.net/caojengineer/article/details/51838394。问题发生在termios.h文件中，在Android 19或Android 21之后发生了变化所以，我简单的做法是将来自Android 19 ndk粘贴的副本termios.h链接到我的.c文件所在的目录，并将#include <termios.h>更改为#include termios.h。请参阅上面的代码段。

Android原生开放串口

1 个答案: