Arduino与Java的接口问题
我遵循了测试流程,但在测试中遇到了一些问题。目前,当我尝试手动输入时,我的Arduino程序运行良好 Arduino上的C代码段:Arduino与Java的接口问题,java,c,serial-port,arduino,Java,C,Serial Port,Arduino,我遵循了测试流程,但在测试中遇到了一些问题。目前,当我尝试手动输入时,我的Arduino程序运行良好 Arduino上的C代码段: char line[20]; int line_pos = 0; char action[10]; unsigned long duration; boolean data_ready = false; void setup() { Serial.begin(9600); delay(1500); Serial.println("Ready!"); }
char line[20];
int line_pos = 0;
char action[10];
unsigned long duration;
boolean data_ready = false;
void setup()
{
Serial.begin(9600);
delay(1500);
Serial.println("Ready!");
}
void loop()
{
char state;
if(Serial.available()>0)
{
delay(20);
state = Serial.read();
if(state == '!')
{
data_ready = true;
line[line_pos] = state;
line_pos = 0;
}
else
{
line[line_pos] = state;
line_pos = line_pos + 1;
}
if(data_ready == true)
{
split(line);
Serial.print(action);
delay(20);
Serial.print("!");
delay(20);
Serial.print(duration);
delay(20);
Serial.print("!");
Serial.println("Data has been split");
if(strcmp(action, "left") == 0)
{
Serial.println("Received left");
}
else if(strcmp(action, "right") == 0)
{
Serial.println("Received rightt");
}
else if(strcmp(action, "straight") == 0)
{
Serial.println("Received straight");
}
memset(line, 0, 20);
data_ready = false;
}
}
}
void split(char input[20])
{
char *param, *ptr;
param = strtok_r(input, "#", &ptr);
strncpy(action, param, sizeof(action));
action[sizeof(action)-1] = '\0';
param = strtok_r(NULL, "!", &ptr);
duration = strtoul(param, ¶m, 10);
}
当我输入“left#123!”时,我在COM中得到如下输出,结果与预期一致。这里没有问题:
准备好了!
左边123!数据已被拆分
收到左键
下面是我的Java代码:
import java.io.InputStream;
import java.io.OutputStream;
import gnu.io.CommPortIdentifier;
import gnu.io.SerialPort;
import gnu.io.SerialPortEvent;
import gnu.io.SerialPortEventListener;
import java.util.Enumeration;
public class SerialTest implements SerialPortEventListener {
SerialPort serialPort;
/** The port we're normally going to use. */
private static final String PORT_NAMES[] = {
"/dev/tty.usbserial-A9007UX1", // Mac OS X
"/dev/ttyUSB0", // Linux
"COM3", // Windows
};
/** Buffered input stream from the port */
private InputStream input;
/** The output stream to the port */
private OutputStream output;
/** Milliseconds to block while waiting for port open */
private static final int TIME_OUT = 2000;
/** Default bits per second for COM port. */
private static final int DATA_RATE = 9600;
private String display = "";
public void initialize() {
CommPortIdentifier portId = null;
Enumeration portEnum = CommPortIdentifier.getPortIdentifiers();
// iterate through, looking for the port
while (portEnum.hasMoreElements()) {
CommPortIdentifier currPortId = (CommPortIdentifier) portEnum.nextElement();
for (String portName : PORT_NAMES) {
if (currPortId.getName().equals(portName)) {
portId = currPortId;
break;
}
}
}
if (portId == null) {
System.out.println("Could not find COM port.");
return;
}
try {
// open serial port, and use class name for the appName.
serialPort = (SerialPort) portId.open(this.getClass().getName(),
TIME_OUT);
// set port parameters
serialPort.setSerialPortParams(DATA_RATE,
SerialPort.DATABITS_8,
SerialPort.STOPBITS_1,
SerialPort.PARITY_NONE);
// open the streams
input = serialPort.getInputStream();
output = serialPort.getOutputStream();
// add event listeners
serialPort.addEventListener(this);
serialPort.notifyOnDataAvailable(true);
} catch (Exception e) {
System.err.println(e.toString());
}
}
/**
* This should be called when you stop using the port.
* This will prevent port locking on platforms like Linux.
*/
public synchronized void close() {
if (serialPort != null) {
serialPort.removeEventListener();
serialPort.close();
}
}
/**
* Handle an event on the serial port. Read the data and print it.
*/
public synchronized void serialEvent(SerialPortEvent oEvent) {
if (oEvent.getEventType() == SerialPortEvent.DATA_AVAILABLE) {
try {
int available = input.available();
byte chunk[] = new byte[available];
input.read(chunk, 0, available);
System.out.println(display);
display += (new String(chunk)).trim();
if(display.contains("!"))
{
display = display.substring(0, display.indexOf("!"));
if(display.equals("Ready"))
{
String reply = "left#123!";
byte reply_byte[] = new byte[reply.length()];
reply_byte = reply.getBytes("UTF-16LE");
output.write(reply_byte);
}
display = "";
}
} catch (Exception e) {
System.err.println(e.toString());
}
}
// Ignore all the other eventTypes, but you should consider the other ones.
}
public static void main(String[] args) throws Exception {
SerialTest main = new SerialTest();
main.initialize();
System.out.println("Started");
}
}
以下是Java代码在控制台中打印出来的内容:
Rea
L
0
资料
数据仓库
达塔哈斯比
Datahasbe sp
数据已被拆分
串行输入似乎不是以流畅的方式读取,而是以重复的部分读取。有人能帮我诊断问题并给我一个解决方案吗?这里至少有两件事需要注意,但这是基于我对Java以外的语言的经验,因此它可能不会以完全相同的方式运行 首先,事件看起来像是在几个字符后触发的,也许你的Arduino发送速度不够快,无法同时显示所有字符。这会导致Java代码重复输出,因为您正在打印
display
,然后将新的块添加到其中。如果你找不到感叹号,它永远不会被清除。您最好打印chunk
,以便准确查看收到的内容
第二种情况是,您可能只接收新数据的事件,因此,如果在触发事件和调用input.read()
之间出现新数据,则不会触发另一个事件。最好在事件处理程序中有一个循环,在仍然有可用数据时继续,例如:
public synchronized void serialEvent(SerialPortEvent oEvent) {
if (oEvent.getEventType() == SerialPortEvent.DATA_AVAILABLE) {
try {
int available = input.available();
while (available > 0)
{
byte chunk[] = new byte[available];
input.read(chunk, 0, available);
System.out.println(new String(chunk));
// Perform your packet processing here
// See if there is any more data that came in while we were
// processing the event
available = input.available();
}
} catch (Exception e) {
System.err.println(e.toString());
}
}
// Ignore all the other eventTypes, but you should consider the other ones.
}
谢谢在处理事件时,如何准确地检查是否有新数据传入?我如何知道这些新数据是否不是重复的旧数据?@ask:您使用循环检查新数据,调用input.available()
,并进行处理,直到其读数为零。它不会重复旧数据,因为当您调用input.read()
时,将从输入中提取您读取的字节数,以便下次不会读取它们。它正常工作了吗。但是使用了if语句,而不是while循环。每当一个字节到达时,就会调用serialEvent函数。