4. Asynchronous api

Asynchronous api example

Remember to check the example module for a complete example

Use

Now that we already have our UsbSerialDevice object this is what needs to be done in order to use the Asynchronous api

UsbSerialDevice serial = UsbSerialDevice.createUsbSerialDevice(device, usbConnection); 
...
serial.open();
serial.setBaudRate(115200);
serial.setDataBits(UsbSerialInterface.DATA_BITS_8);
serial.setParity(UsbSerialInterface.PARITY_ODD);
serial.setFlowControl(UsbSerialInterface.FLOW_CONTROL_OFF); 

Flow control is also supported in CP210x and FTDI devices

/**
Values:
    UsbSerialInterface.FLOW_CONTROL_OFF
    UsbSerialInterface.FLOW_CONTROL_RTS_CTS 
    UsbSerialInterface.FLOW_CONTROL_DSR_DTR
**/
serial.setFlowControl(UsbSerialInterface.FLOW_CONTROL_RTS_CTS);

Reading from the serial port is performed through a callback. Note that this callback is not executed in the UI thread. That means you can' touch anything UI related here.

private UsbSerialInterface.UsbReadCallback mCallback = new UsbSerialInterface.UsbReadCallback() {

		@Override
		public void onReceivedData(byte[] arg0) 
		{
			// Code here :)
		}
		
};

Pass a mCallback reference to the UsbSerialDevice object

serial.read(mCallback);

Now, write something

serial.write("DATA".getBytes());

You can also set RTS and DTR signals

serial.setRTS(true); // Raised
serial.setRTS(false); // Not Raised
serial.setDTR(true); // Raised
serial.setDTR(false); // Not Raised

Changes in the CTS and DSR lines will be received in the same manner. Define a callback and pass a reference of it.

private UsbSerialInterface.UsbCTSCallback ctsCallback = new UsbSerialInterface.UsbCTSCallback() {
        @Override
        public void onCTSChanged(boolean state) {
           // Code here :)
        }
    };
    
private UsbSerialInterface.UsbDSRCallback dsrCallback = new UsbSerialInterface.UsbDSRCallback() {
        @Override
        public void onDSRChanged(boolean state) {
           // Code here :)
        }
    };
    
serial.getCTS(ctsCallback);
//serial.getDSR(dsrCallback);

When you are done, close the device

serial.close();

Supported baud rates

300, 600, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200, 230400, 460800, 921600