[英]Serial ports writing/reading in linux
我需要通過Raspberry Pi上的串口實現兩台設備之間的通信(板載最后一個Raspbian)。 兩者都使用CP2102控制器並連接到Pi。
終奌站:
pi@pi ~ $ ls -l /dev/serial/by-id
total 0
Silicon_Labs_CP2102_USB_to_UART_Bridge_Controller_0001-if00-port0 -> ../../ttyUSB2
pi@pi ~ $ ls -l /dev/serial/by-path
total 0
platform-bcm2708_usb-usb-0:1.2.1:1.0-port0 -> ../../ttyUSB1
platform-bcm2708_usb-usb-0:1.2.4:1.0-port0 -> ../../ttyUSB2
platform-bcm2708_usb-usb-0:1.3:1.0-port0 -> ../../ttyUSB0
通常當我向SERIAL A發送命令時,Device A通過SERIAL A回復並通過SERIAL B發送數據。之后我需要將這些數據重新轉換為Device B(SERIAL C)並從SERIAL C接收回答。
問題是SERIAL A回復出現在SERIAL B上,SERIAL B數據出現在SERIAL A上。
我嘗試過不同的語言和串行庫,但結果是一樣的。 所以問題是:為什么在使用Raspberry Pi時會發生這種情況? 如何在Raspberry Pi上實現此功能?
PS這兩個設備都正常工作。 我的C#代碼非常完美。 我為該實現使用了System.IO.Ports.SerialPort類,它看起來像Pi4J和RXTX解決方案。
PPS我嘗試在RPi上使用的一些代碼:
Serial ,C ++ :(非常糟糕的一段代碼)
Serial port("/dev/ttyUSB2", 115200U);
Serial port1("/dev/ttyUSB1", 115200U);
port1.setTimeout(Timeout::max(), 250, 0, 250, 0);
port.setTimeout(Timeout::max(), 250, 0, 250, 0);
cout << "Is the serial port open?";
if (port1.isOpen()) {
cout << " Yes." << endl;
uint8_t data[2] = { 0xAA, 0x00 };
port1.write(data, 2);
data[1] = 0xFF;
sleep(1);
port1.write(data, 2);
while (port.available() < 7);
int av = port.available();
string ss;
port.read(ss, av);
for (int i = 0; i < av; i++){
cout << (uint)ss.at(i) << " ";
}
cout << "av: " + (uint)av << endl;
}
RXTX,Java:
public class Bridge_rxtx {
public static final int baudrate = 115200;
protected SerialPort spDevB_Data;
SerialReader devB_DataListener;
protected SerialPort spDevA_Data;
SerialReader DevA_DataListener;
protected SerialPort spDevA_Control;
SerialPortEventListener DevA_ControlListener;
public Bridge_rxtx(String comDevB_Data, String comDevA_Data, String comDevA_Control) {
try {
spDevB_Data = setupPort(comDevB_Data);
spDevA_Data = setupPort(comDevA_Data);
spDevA_Control = setupPort(comDevA_Control);
} catch (Exception ignored){
ignored.printStackTrace();
}
try {
devB_DataListener = new SerialReader(spDevB_Data.getInputStream(), spDevA_Data.getOutputStream(), "B-A");
DevA_DataListener = new SerialReader(spDevA_Data.getInputStream(), spDevB_Data.getOutputStream(), "A-B");
DevA_ControlListener = new SerialPortEventListener() {
@Override
public void serialEvent(SerialPortEvent spe) {
throw new UnsupportedOperationException("Not supported yet.");
}
};
spDevB_Data.notifyOnDataAvailable(true);
spDevA_Data.notifyOnDataAvailable(true);
spDevA_Control.notifyOnDataAvailable(true);
} catch (IOException ex) {
Logger.getLogger(Bridge_rxtx.class.getName()).log(Level.SEVERE, null, ex);
}
}
public void launchBridge(){
System.out.println("Starting...");
try {
spDevA_Control.getOutputStream().write(new byte[] {(byte)0xAA, (byte) 0x00}, 0, 2);
} catch (IOException ex) {
Logger.getLogger(Bridge_rxtx.class.getName()).log(Level.SEVERE, null, ex);
}
try {
Thread.sleep(200);
} catch (InterruptedException ex) {
Logger.getLogger(Bridge_rxtx.class.getName()).log(Level.SEVERE, null, ex);
}
try {
spDevA_Control.getOutputStream().write(new byte[] {(byte)0xAA, (byte) 0xFF}, 0, 2);
} catch (IOException ex) {
Logger.getLogger(Bridge_rxtx.class.getName()).log(Level.SEVERE, null, ex);
}
System.out.println("Started");
}
SerialPort setupPort(String portName) throws Exception {
SerialPort serialPort = null;
CommPortIdentifier portIdentifier = CommPortIdentifier.getPortIdentifier(portName);
if (portIdentifier.isCurrentlyOwned()) {
System.out.println("Error: Port is currently in use");
} else {
CommPort commPort = portIdentifier.open(this.getClass().getName(), 2000);
if (commPort instanceof SerialPort) {
serialPort = (SerialPort) commPort;
serialPort.setSerialPortParams(baudrate, SerialPort.DATABITS_8, SerialPort.STOPBITS_1, SerialPort.PARITY_NONE);
} else {
System.out.println("Error: Only serial ports are handled by this code.");
}
}
return serialPort;
}
public static void main(String[] args) {
Bridge_rxtx bridge = new Bridge_rxtx("/dev/ttyUSB0", "/dev/ttyUSB2", "/dev/ttyUSB1");
bridge.launchBridge();
}
}
Pi4J,Java:
public class Bridge {
public static Bridge instance;
public static final int baudrate = 115200;
protected Serial spDevB_Data;
SerialDataListener devB_DataListener;
protected Serial spDevA_Data;
SerialDataListener devA_DataListener;
protected Serial spDevA_Control;
SerialDataListener devA_ControlListener;
private Bridge() {
}
public Bridge(String comDevB_Data, String comDevA_Data, String comDevA_Control) {
instance = this;
devA_ControlListener = new SerialDataListener() {
//SerialDataEvent in Pi4J doesn't support binary
//data by default. I implemented this myself.
public void dataReceived(SerialDataEvent event) {
System.out.println(bytesToHex(toPrimitives(event.getBinaryData())));
}
};
devB_DataListener = new SerialDataListener() {
public void dataReceived(SerialDataEvent event) {
byte[] data = toPrimitives(event.getBinaryData());
instance.spDevA_Data.write(data);
System.out.println("B -> A: " + bytesToHex(data));
}
};
devA_DataListener = new SerialDataListener() {
public void dataReceived(SerialDataEvent event) {
byte[] data = toPrimitives(event.getBinaryData());
instance.spDevB_Data.write(data);
try {
Thread.sleep(15);
} catch (InterruptedException ex) {
Logger.getLogger(Bridge.class.getName()).log(Level.SEVERE, null, ex);
}
System.out.println("B <- A: " + bytesToHex(data));
}
};
spDevB_Data = SerialFactory.createInstance();
spDevB_Data.addListener(devB_DataListener);
spDevA_Data = SerialFactory.createInstance();
spDevA_Data.addListener(devA_ControlListener);
spDevA_Control = SerialFactory.createInstance();
spDevA_Control.addListener(devA_DataListener);
spDevB_Data.setMonitorInterval(40);
spDevA_Data.setMonitorInterval(80);
spDevA_Control.setMonitorInterval(25);
spDevB_Data.open(comDevB_Data, baudrate);
spDevA_Data.open(comDevA_Data, baudrate);
spDevA_Control.open(comDevA_Control, baudrate);
}
public void SetupBridge() {
spDevA_Control.write(new byte[]{(byte) 0xAA, (byte) 0x00});
try {
Thread.sleep(20);
} catch (InterruptedException ex) {
Logger.getLogger(Bridge.class.getName()).log(Level.SEVERE, null, ex);
}
spDevA_Control.write(new byte[]{(byte) 0xAA, (byte) 0xFF});
}
}
沒有足夠的聲譽評論:我的有根據的猜測是,它與Linux枚舉硬件的方式有關。 我認為您的USB設備可能會有另一個串行路徑,具體取決於使用的發行版和連接順序。
您確定每次都使用相同的USB端口嗎? 並且正確的USB端口映射到/ dev / tty?
您可以通過確保具有相應的udev規則來強制HID始終具有相同的名稱。 這里有一些信息
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