Re: Missing isochronous packets

G'day Tim.
I recently did a similar project: a 375 byte iso packets using an XMEGA,
also in ASF!
(The same one I posted about before, Xiaofan, and I got it to work!)

udi_vendor_iso_in_run(buffer, sizeof(buffer), nullptr) does not cause the
microcontroller to wait!  It just tells the USB controller "on the next iso
request, I want you to transmit sizeof(buffer) bytes, starting at address
buffer and then do nothing when the transaction finishes".  (Note: if a
transaction has already been requested, the function may simply return
without doing anything.  I'm not 100% sure but I think I remember the
source code implying that.)
So your increments a huge number of times between transactions, since
there's nothing blocking it!

To fix this, take everything out of the loop!
Run udi_vendor_iso_in_run() only once, and pass in a callback to a function
rather than the NULL ptr.
Then, in the callback function, increment the number and then call
udi_vendor_iso_in_run() again - also with callback!
The callback function will only run once per transaction, after it's
complete.

Also, you'll want the buffer to be volatile.  If it's not volatile, the CPU
might not write back the data to memory when it's done.  This will cause
hell with the USB's DMA!
One last thing: this probably isn't a LibUSBK question.  An Atmel forum
such as AVRFreaks (or possibly an Arduino forum) would be much more
helpful.  Although, that being said, I get an email notification if you
post here and I've probably just been through the same stuff that you're
going through.  :P

Oh, and P.P.S: If you run into problem with data transfer not being smooth
in the future: double buffer things on both the micro and PC side, and run
two separate, interleaved Iso Contexts and OvlK Handles PC side.  The
callback method works fine for continuous streaming on my XMEGA, just make
sure you swap buffers each time!

Good luck, mate!
~Chris

On 23 July 2015 at 17:12, Tim Hutt <[email protected]> wrote:

> I'm trying to transmit 64 byte isochronous USB packets over a USB high
> speed link from a SAM3X (in an Arduino Due) to a libusbk program (basically
> the example benchmark program it comes with).
>
> I have one isochronous endpoint on the device and it sends data in a tight
> loop like this (using Atmel's SDK):
>
> uint8_t buffer[UDI_VENDOR_EPS_SIZE_ISO_HS]; // 64 bytes.for (int i = 0; i < sizeof(buffer); ++i)
>     buffer[i] = i;for (;;){
>     led = !led;
>     udi_vendor_iso_in_run(buffer, sizeof(buffer), nullptr);
>     // TODO: How to wait until it is finished?
>     buffer[0]++;
>     if (buffer[0] == 0)
>         buffer[1]++;}
>
> The receiving program is basically the example iso read program from
> libusbk. It writes data to a log file, including the first two bytes of
> each packet which I increment as shown above. It requests 128 packets per
> frame, and outputs data like this:
>
> #6: StartFrame=00DDE360h LastFrameCount=16 TransferLength=8192 BPS-average:390409.30
>   #0000: Length=64 C0h 3Dh
>   #0001: Length=64 E1h 3Dh
>   #0002: Length=64 01h 3Eh
>   #0003: Length=64 23h 3Eh
>   #0004: Length=64 44h 3Eh
>   #0005: Length=64 64h 3Eh
>   #0006: Length=64 85h 3Eh
>   #0007: Length=64 A6h 3Eh
>   #0008: Length=64 C7h 3Eh
>  ... snip ...
>   #0120: Length=64 34h 4Dh
>   #0121: Length=64 55h 4Dh
>   #0122: Length=64 76h 4Dh
>   #0123: Length=64 97h 4Dh
>   #0124: Length=64 B8h 4Dh
>   #0125: Length=64 D9h 4Dh
>   #0126: Length=64 FAh 4Dh
>   #0127: Length=64 1Bh 4Eh
>
> As you can see, it works but is skipping loads of the packets. I'd like to
> know why! The data rate is really low compared to what USB 2 can do. I'm
> kind of at a loss here as I don't know how to wait until a transfer is
> completed in a tight loop on the SAM3X. Also... it should work right?
>
> Here are the USB descriptors (I snipped some unused endpoints):
>
> Device Power State:               PowerDeviceD0
>
>        ---===>Device Information<===---English product name: ""
> ConnectionStatus:                  Current Config Value:              0x01  -> Device Bus Speed: HighDevice Address:                    0x05Open Pipes:                           0*!*ERROR:  No open pipes!
>
>           ===>Device Descriptor<===
> bLength:                           0x12
> bDescriptorType:                   0x01
> bcdUSB:                          0x0200
> bDeviceClass:                      0x00  -> This is an Interface Class Defined Device
> bDeviceSubClass:                   0x00
> bDeviceProtocol:                   0x00
> bMaxPacketSize0:                   0x40 = (64) Bytes
> idVendor:                        0x1111 = Dade Behring, Inc.  // Screw the USB-IF!
> idProduct:                       0x2223
> bcdDevice:                       0x0100
> iManufacturer:                     0x01
>      English (United States)  ""
> iProduct:                          0x02
>      English (United States)  ""
> iSerialNumber:                     0x00
> bNumConfigurations:                0x01
>
>        ---===>Full Configuration Descriptor<===---
>
>           ===>Configuration Descriptor<===
> bLength:                           0x09
> bDescriptorType:                   0x02
> wTotalLength:                    0x0045  -> Validated
> bNumInterfaces:                    0x01
> bConfigurationValue:               0x01
> iConfiguration:                    0x00
> bmAttributes:                      0x80  -> Bus PoweredMaxPower:                          0x32 = 100 mA
>
>           ===>Interface Descriptor<===
> bLength:                           0x09
> bDescriptorType:                   0x04
> bInterfaceNumber:                  0x00
> bAlternateSetting:                 0x00
> bNumEndpoints:                     0x00
> bInterfaceClass:                   0xFF  -> Interface Class Unknown to USBView
> bInterfaceSubClass:                0xFF
> bInterfaceProtocol:                0xFF
> iInterface:                        0x00
>
>           ===>Interface Descriptor<===
> bLength:                           0x09
> bDescriptorType:                   0x04
> bInterfaceNumber:                  0x00
> bAlternateSetting:                 0x01
> bNumEndpoints:                     0x06
> bInterfaceClass:                   0xFF  -> Interface Class Unknown to USBView
> bInterfaceSubClass:                0xFF
> bInterfaceProtocol:                0xFF
> iInterface:                        0x00
> (snipped irrelevant endpoints)
>
>           ===>Endpoint Descriptor<===       <---- This is the endpoint I'm using.
> bLength:                           0x07
> bDescriptorType:                   0x05
> bEndpointAddress:                  0x81  -> Direction: IN - EndpointID: 1
> bmAttributes:                      0x01  -> Isochronous Transfer Type, Synchronization Type = No Synchronization, Usage Type = Data Endpoint
> wMaxPacketSize:                  0x0040 = 1 transactions per microframe, 0x40 max bytes
> bInterval:                         0x01
>
> Does anyone have any ideas?
>
> Cheers,
>
> Tim
>
>
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