我正在尝试编写一个简单的Java程序,根据用户在某些物理传感器上的激励来显示馈送到Arduino板的模拟输入。
如果我自己使用Arduino程序并查看串行监视器,我会看到基于用户输入的模拟读取立即更新。但是,当从我的Java程序读取输入时,物理激励和值的显示之间存在显着的延迟(5-6秒)。
上传到Arduino的代码非常简单,只需循环通过一堆模拟端口并打印数据:
void setup() {
Serial.begin(9600);
pinMode(30, OUTPUT);
}
void loop()
digitalWrite(30, HIGH);
for (int i = 0; i < 10; i++) {
int sensorValue = analogRead(i);
Serial.print(String(i) + ":");
Serial.println(sensorValue);
}
}
我正在使用的Java代码几乎完全从提供的here示例中复制,但我更新了端口名称以适用于我的系统(Mac OS X 10.10.3)。
这是Java代码:
import java.io.BufferedReader;
import java.io.InputStreamReader;
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/cu.usbmodem1411",
"/dev/cu.usbmodem1451",
};
/**
* A BufferedReader which will be fed by a InputStreamReader
* converting the bytes into characters
* making the displayed results codepage independent
*/
private BufferedReader 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;
public void initialize() {
CommPortIdentifier portId = null;
Enumeration portEnum = CommPortIdentifier.getPortIdentifiers();
//First, Find an instance of serial port as set in PORT_NAMES.
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 = new BufferedReader(new InputStreamReader(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 {
String inputLine=input.readLine();
System.out.println(inputLine);
} 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();
Thread t=new Thread() {
public void run() {
//the following line will keep this app alive for 1000 seconds,
//waiting for events to occur and responding to them (printing incoming messages to console).
try {Thread.sleep(1000000);} catch (InterruptedException ie) {}
}
};
t.start();
System.out.println("Started");
}
}
所有程序都打印出Arduino串行监视器的值,但是它通过Java需要比Arduino程序本身更长(5-6秒)。
1)为什么会发生这种情况? 2)我该如何解决?
答案 0 :(得分:0)
对我有用的答案是在我的Arduino代码中添加delay
方法。显然,Java正在被输入的速度所淹没。
当然,Java仍然可以以足够快的速度读取,但有任何实际差异。