Android Question USBconnection Bulktransfer

[wroyw]

Hi,
I write my own CP210x class module.
At time I can get/set any parameters.
Write to my device works also ( I see it on my oscilloscope)
BUT when I need Bulktransfer to read data from my device I get always -1 .
The Inqueue count is okay but I can't read the data.

 

[Erel]

Implementing the protocol yourself will be difficult. Both UsbSerial and felUsbSerial libraries support these chips.

 

[wroyw]

I know, but I need the direct write and read functions without events.
The communications works fine , but the reading of the received bytes doesn't work right.
I get as result of Bulktransfer 1 or -1 but not my requested count ...
The Inqueue count is correct (GET_COMM_STATUS)

 

[wroyw]

if I call " USBdev.USBconnection.StartListening("") " before Bulk read it seems to work ...

 

[Erel]

I know, but I need the direct write and read functions without events.

This will not work as UsbManager is also asynchronous. Slow operations should never be done with the main thread. This is why you need to use AsyncStreams for USB communication.

 

[wroyw]

I think it work fine for me ...

Now I can scan the connected USB devices with short commands without events like this :

   optDevice.OpenDevice(0,9600)
   optDevice.Purge(True,True)
   Dim answ As TReceiveBuffer = optDevice.SendDeviceCommand(Array As Short (0x2a,0x00,0x2a),18,250) ' (sendarray , receivecount , timeoutms)
   optDevice.CloseDevice

For the general communication I use the USBserial lib.

 

[wroyw]

You are right. It works well only sometimes.
What is the reason that the Bulktransfer read doesn't read the bytes from my CP210x device ?
The CP210x say 5 bytes in input queue, but Bulktranfer result is 1 or -1 but not 5 ?

 

[wroyw]

Erel,
is that a general Android problem or a special B4A problem/issue ?

 

[Erel]

It is not a B4A problem. The library code just delegates the call to the native API.

 

[wroyw]

So is it an Android problem ? It is not possible to read bytes from USB device with the Bulktranfer command ?

 

[Erel]

So is it an Android problem ?

I guess that you are not using the API correctly. As I wrote 5 times this is difficult to implement these protocols. Fortunately there are two libraries that already implement it.

You can see their source code: https://github.com/felHR85/UsbSeria...a/com/felhr/usbserial/CP2102SerialDevice.java
It is based on the same methods wrapped by B4A Usb library.

 

[wroyw]

I wrote the same in Android Studio and there it works fine . I get every time the right bytes from my queue and Bulktranfer return the right count of reading bytes ...

 

[wroyw]

Here is what I do :

UsbManager manager = (UsbManager) getSystemService(Context.USB_SERVICE);
HashMap<String, UsbDevice> deviceList = manager.getDeviceList();
edt.append("USB device count :" + String.valueOf(deviceList.size()) + "\r\n");
Iterator<UsbDevice> deviceIterator = deviceList.values().iterator();
while (deviceIterator.hasNext()) {
  UsbDevice device = deviceIterator.next();
  UsbInterface devInterface = device.getInterface(0); 
  int devInterfaceID = devInterface.getId();
  UsbEndpoint OutEndPoint = devInterface.getEndpoint(0);
  UsbEndpoint InEndPoint = devInterface.getEndpoint(1);
  UsbDeviceConnection connection = manager.openDevice(device);
  connection.claimInterface(devInterface, true); 
  byte[] bytes;
  connection.controlTransfer(CP210x_REQTYPE_HOST2DEVICE, CP210x_IFC_ENABLE, CP210x_IFC_ON, devInterfaceID, null, 0,250);
  connection.controlTransfer(CP210x_REQTYPE_HOST2DEVICE, CP210x_SET_MHS, CP210x_MHS_DTR_ON, devInterfaceID, null, 0, 200); 
  int br = 3686400 / 9600;
  connection.controlTransfer(CP210x_REQTYPE_HOST2DEVICE, CP210x_SET_BAUDDIV, br, devInterfaceID, null, 0, 200);
  bytes = new byte[]{0x2a, 0x00, 0x2a}; 
  byte[] InBuff = new byte[100];
  connection.controlTransfer(CP210x_REQTYPE_DEVICE2HOST, CP210x_GET_COMM_STATUS, 0, devInterfaceID, InBuff, 0x0014, 200); 
  for (int i = 0; i < 20; i++) {
  connection.bulkTransfer(OutEndPoint, bytes, 3, 200);
  while (InBuff[9]!=18) {
    connection.controlTransfer(CP210x_REQTYPE_DEVICE2HOST, CP210x_GET_COMM_STATUS, 0, devInterfaceID, InBuff, 0x0014, 200);
  }
  int rc = connection.bulkTransfer(InEndPoint, InBuff, 18, 500); 
  if (rc == 18) {
   edt.append("18 Zeichen empfangen !\r\n");
  } else {
    edt.append("ERROR Zeichen empfangen !\r\n");
  }
  connection.close();
}

 

[Erel]

This is the library code:

  public int BulkTransfer (UsbEndpoint Endpoint, byte[] Buffer, int Length, int Timeout) {
     return connection.bulkTransfer(Endpoint, Buffer, Length, Timeout);
   }

As you can see it just calls the native API. There is no logic here. The same is true for controlTransfer.

You can wrap this code in your own library if you like and use it.