CODEWITHSUNDEEP
javaandroidarduinoandroid-usbusb-hostcontroller
Enrique Sanchez
Enrique Sanchez

Reputation: 1

Android UsbConnection.bulkTransfer() works but UsbConnection.controlTransfer always returns -1

I'm sending information to an Arduino Nano from an Android device. bulkTransfer returns the correct value (length of data transmitted) but the Arduino receives strange values. I think it is because the baud rate of the Arduino (9600) is different from the baud rate the Android is transmitting, but I can't find the way to know which is this value.

So I have tried to call controlTransfer to set the baud rate of the Android but controlTransfer always return -1. I don't understand why bulkTransfer works but controlTransfer fails.

I'm using this code:

public int sendData(byte[] nbyte) throws IOException, NullPointerException {
  if(nbyte == null) throw new NullPointerException("nbyte cannot be null");
  int result = this.usbDeviceConnection.controlTransfer(0x40, 0, 0, 0, null, 0, 0);// reset
  result = this.usbDeviceConnection.controlTransfer(0x40, 0, 1, 0, null, 0, 0);// clear Rx
  result = this.usbDeviceConnection.controlTransfer(0x40, 0, 2, 0, null, 0, 0);// clear Tx
  result =  this.usbDeviceConnection.controlTransfer(0x40, 0x03, 0x4138, 0, null, 0, 0);
  int len = this.usbDeviceConnection.bulkTransfer(this.usbEndpoint, nbyte, nbyte.length, 5000);
  if(len == -1) throw new IOException("Bulktransfer failed");
  return len;
}

Upvotes: 0

Views: 687

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