Android 串口开发 支持N-8-1(数据位停止位校验方式) 设定
依据使用Cmake的方式 对串口开发的便捷了很多,但是的大多数例子,都不支持对数据位、停止位、校验位的设定,毕竟大多数人并不会linux 下的串口编程,查阅很多例子和资料。主要参考了:https://www.cnblogs.com/rui1236/p/5988074.html>。但是按照这个例子中的C的写法无校验(N-8-1)的时候正常,有奇偶校验发出去的准确,但是收到的却不准确。比如HEX(十六进制) 95 收到变成15 第一位被截取了。
部分分析实现过程参考
最后是又从参考了部分linux下的串口对该奇偶校验部分更改实现:
最后改后的 C源码:
#include <termios.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <jni.h>
#include <strings.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)
int fd;
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;
}
}
/**
* 设置串口数据,校验位,速率,停止位
* @param nBits 类型 int数据位 取值 位7或8
* @param nEvent 类型 char 校验类型 取值N ,E, O,,S
* @param mStop 类型 int 停止位 取值1 或者 2
*/
int set_opt(jint nBits, jchar nEvent, jint nStop){
LOGE("set_opt:nBits=%d,nEvent=%c,nSpeed=%d,nStop=%d", nBits, nEvent, nStop);
LOGE("set_opt:nStop=%d", nStop);
struct termios newtio;
if(tcgetattr(fd, & newtio) != 0){
LOGE("setup serial failure");
return -1;
}
bzero( &newtio, sizeof(newtio));
//c_cflag标志可以定义CLOCAL和CREAD,这将确保该程序不被其他端口控制和信号干扰,同时串口驱动将读取进入的数据。CLOCAL和CREAD通常总是被是能的
newtio.c_cflag |= CLOCAL | CREAD;
//设置数据位数
switch(nBits) {
case 7:
LOGE("设置数据位数==7");
newtio.c_cflag &= ~CSIZE;
newtio.c_cflag |= CS7;
break;
default:
case 8:
LOGE("设置数据位数==默认==8");
newtio.c_cflag &= ~CSIZE;
newtio.c_cflag |= CS8;
break;
}
//设置校验位
switch(nEvent) {
case 'o':
case 'O':
newtio.c_cflag |= (PARODD | PARENB);
newtio.c_iflag |= INPCK;
LOGE("设置校验位O奇校验位");
break;
case 'e':
case 'E':
newtio.c_cflag |= PARENB;
newtio.c_cflag &= ~PARODD;
newtio.c_iflag |= INPCK;
LOGE("设置校验位E偶校验位");
break;
case 'N':
case 'n':
newtio.c_cflag &= ~PARENB; //清除校验位
LOGE("设置校验位N");
break;
default:
newtio.c_cflag &= ~PARENB; //清除校验位
LOGE("设置校验位默认N");
break;
}
// 设置停止位
switch(nStop) {
case 1:
newtio.c_cflag &= ~CSTOPB;
break;
case 2:
newtio.c_cflag |= CSTOPB;
break;
default:
newtio.c_cflag &= ~CSTOPB;
// LOGW("nStop:%d,invalid param", nStop);
break;
}
newtio.c_cc[VTIME] = 0;//设置等待时间
newtio.c_cc[VMIN] = 0;//设置最小接收字符
tcflush(fd, TCIFLUSH);
if(tcsetattr(fd, TCSANOW, & newtio) != 0) {
LOGE("options set error");
return -1;
}
LOGE("options set success");
return 1;
}
/*
* Class: android_serialport_SerialPort
* Method: open
* Signature: (Ljava/lang/String;II)Ljava/io/FileDescriptor;
*/
JNIEXPORT jobject JNICALL Java_com_silencefun_comtest_serialport_SerialPort_open
(JNIEnv *env, jclass thiz, jstring path, jint baudrate,
jint databits, jint stopbits, jchar parity) {
speed_t speed;
jobject mFileDescriptor;
/*波特率 */
{
speed = getBaudrate(baudrate);
if (speed == -1) {
/* TODO: throw an exception */
LOGE("Invalid baudrate");
return NULL;
}
}
/* Opening device */
{
jint flags = 0;
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 | O_NONBLOCK);
//fd=fd;
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);
//设置波特率
cfsetispeed(&cfg, speed);
cfsetospeed(&cfg, speed);
if (tcsetattr(fd, TCSANOW, &cfg)) {
LOGE("tcsetattr() failed");
close(fd);
/* TODO: throw an exception */
return NULL;
}
//配置校验位 停止位等等
set_opt(databits, parity, stopbits);
}
/* 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_silencefun_comtest_serialport_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);
}
在写Native 方法的时候 要对应参数类型和位置,SerialPort类中改:
public class SerialPort {
private static final String TAG = "SerialPort";
/*
* Do not remove or rename the field mFd: it is used by native method close();
*/
private FileDescriptor mFd;
private FileInputStream mFileInputStream;
private FileOutputStream mFileOutputStream;
public SerialPort(File device, int baudrate, int dataBits, int stopBits, char parity) throws SecurityException, IOException {
mFd = open(device.getAbsolutePath(), baudrate,dataBits,stopBits,parity);
if (mFd == null) {
Log.e(TAG, "native open returns null");
throw new IOException();
}
mFileInputStream = new FileInputStream(mFd);
mFileOutputStream = new FileOutputStream(mFd);
}
public SerialPort(File device, int baudrate, int flags) throws SecurityException, IOException {
mFd = open(device.getAbsolutePath(), baudrate,8,2,'E');
if (mFd == null) {
Log.e(TAG, "native open returns null");
throw new IOException();
}
mFileInputStream = new FileInputStream(mFd);
mFileOutputStream = new FileOutputStream(mFd);
}
// Getters and setters
public InputStream getInputStream() {
return mFileInputStream;
}
public OutputStream getOutputStream() {
return mFileOutputStream;
}
/**
* 调用JNI中 打开方法的声明
* @param dataBits 类型 int数据位 取值 位7或8
* @param parity char校验类型 取值N ,E, O,,S
* @param stopBits 类型 int 停止位 取值1 或者 2
* @return
*/
private native static FileDescriptor open(String path, int baudrate, int dataBits, int stopBits, char parity);
public native void close();
static {
System.loadLibrary("native-lib");
}
}
这样再打开 串口,也就是SerialHelper类中增加成员变量和set方法
// 默认 N-8-1
private char parity = 'N';//char校验类型 取值N ,E, O,,S
private int dataBits = 8;//dataBits 类型 int数据位 取值 位7或8
private int stopBits = 1;//stopBits 类型 int 停止位 取值1 或者 2
/**
*设定校验位等
*/
public void setN81(String idataBits, String istopBits, String cparity) {
this.parity =cparity.charAt(0);
this.dataBits = Integer.parseInt(idataBits);
this.stopBits = Integer.parseInt(istopBits);
}
同时更改原来的打开方法 :
mSerialPort = new SerialPort(new File(sPort), iBaudRate, dataBits, stopBits, parity);
// 对比原来的 初始化方法
// mSerialPort = new SerialPort(new File(sPort), iBaudRate, 0);
同样在初始化串口对象之后打开串口之前,进行N-8-1的设定,然后再打开串口
if (isChecked) {
//ComA=new SerialControl("/dev/s3c2410_serial0", "9600");
ComA.setPort(SpinnerCOMA.getSelectedItem().toString());
ComA.setN81(Spinner_databits1.getSelectedItem().toString(),
Spinner_stopbits1.getSelectedItem().toString(),
Spinner_parity1.getSelectedItem().toString());
//setN81(String idataBits, String istopBits, String cparity) {
Log.e("N81----->", Spinner_databits1.getSelectedItem().toString() +
pinner_stopbits1.getSelectedItem().toString() +
Spinner_parity1.getSelectedItem().toString());
ComA.setBaudRate(SpinnerBaudRateCOMA.getSelectedItem().toString());
OpenComPort(ComA);
} else {
CloseComPort(ComA);
checkBoxAutoCOMA.setChecked(false);
}
模拟器中截图:
该项目 github 路径,欢迎建议 指正。 https://github.com/silencefun/ComTest/tree/master/Android_SetN81
部分 分析实现过程 参考
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