Thanks,
Sanjay Gupta<p> </p><p> </p>
------- Original Message -------
Sender : Dan Streetman<ddstr...@ieee.org>
Date : Oct 02, 2013 22:31 (GMT+09:00)
Title : Re: [javax-usb-devel] Hang problem with UsbPipe.syncSubmit(byte[])
On Wed, Oct 2, 2013 at 6:23 AM, SANJAY GUPTA <gupta.san...@samsung.com> wrote:
> Hi All,
>
> Please look below the sample scenario:-
>
> final byte[] outData = new byte[] {
> (byte) 0x00, (byte) 0x01, (byte) 0x02, (byte) 0x03,
> (byte) 0x04, (byte) 0x05, (byte) 0x06, (byte) 0x07,
> (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00,
> (byte) 0x08, (byte) 0x09, (byte) 0x0A, (byte) 0x01B,
> (byte) 0x0C, (byte) 0x0D, (byte) 0x0E, (byte) 0x0F,
> (byte) 0x00, (byte) 0x01, (byte) 0x02, (byte) 0x03,
> (byte) 0x04, (byte) 0x05, (byte) 0x06, (byte) 0x07,
> (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00 }
> final byte[] inData = new byte[13];
>
> log("Synchronously submitting the byte[] to UsbPipe ...");
> outUsbPipe.syncSubmit(data);
>
> //Synchronously read the status from IN UsbPipe
> log("Synchronously reading the status from IN UsbPipe ...");
> inUsbPipe.syncSubmit(inData);
>
> This code is working fine but I am facing problem if I want to change (reduce/reduce/modify) the outData.
> The control gets hang on reading the status data from the Input UsbPipe.
> Any suggestion on below points will be helpful:-
> 1. Is there any specific data format (may be starting header) in the actual data being transferred?
Data formats are entirely up to the device, unless the device
implements a higher level spec (like HID, mass storage, etc) that
itself contains the API for the data format. USB doesn't specify any
data format at all, except for the control pipe 8-byte setup packet
that must preface each control transfer, and the various default
control pipe standard requests (set interface, clear stall, etc).
===> Thanks A lot. I am using a mass-storage device and BULK type UsbEndpoint for data transfer.
But the problem is, suppose I keep the value of outData[8] as non-zero with all other things intact, the submission gets hanged which never completes.
And then I have no choice but the unplug the device.
> 2. What is the data size which can be transferred using single invocation of syncSubmit()?
it's been a while, but IIRC there's no limit in java, although I think
the platform may enforce limits. I don't really remember the details
though. For interrupt pipes, you of course should usually submit
exactly the pipe size (wMaxPacketSize).
===> Mass-storage device and BULK type UsbEndpoint.
> 3. What is the status data size which is received on Input Pipe as a result of out data transfer?
it's entirely dependent on your device. although if your input pipe
is an interrupt pipe, it should be the wMaxPacketSize from the
endpoint descriptor.
Also, assuming your input pipe is interrupt type, it's probably better
for you to keep a buffer on it, which will cause continuous polling of
the device, as required by spec when the device is in use. You can do
that either with a separate Thread that does nothing except
syncSubmit() a buffer or irp to the pipe, then passes the returned
data off somewhere else to process and immediately syncSubmit() a new
buffer, or you can use asyncSubmit() with either a listener on the
pipe or a separate Thread to waitUntilComplete() for the irp, and then
also hand off the returned data to process somewhere else and
immediately sync or async submit again a new buffer. With
asyncSubmit(), you can submit multiple buffers, which is better
because it keeps the low level platform queued up with buffers so that
the device polling never stops, and you don't have to try to be quite
so fast at resubmitting a new buffer.
===> Mass-storage device and BULK type UsbEndpoint.
>
> Thanks in Advance..
> Sanjay Gupta
>
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