PORTS Forum

Ports and Interfaces => USB => Topic started by: Jan Axelson on November 19, 2013, 10:40:12 am

Title: WinUSB now supports isochronous transfers (Windows 8.1 and later)
Post by: Jan Axelson on November 19, 2013, 10:40:12 am

WinUSB now supports isochronous transfers (Windows 8.1 and later):

http://msdn.microsoft.com/en-us/library/windows/hardware/dn376866%28v=vs.85%29.aspx

Title: data transfer from usb flash to usb flash without PC
Post by: Blessed Sone on November 21, 2013, 07:13:42 am

pls i'm on my final yr project on:data transfer from usb flash to usb flash without PC
in my schl we don't the ARM9 processor except the PIC mcu, i wish to know if there is any
PIC that i cn use in place of the ARM

Title: Re: WinUSB now supports isochronous transfers (Windows 8.1 and later)
Post by: Jan Axelson on November 21, 2013, 09:03:14 am

Use a PIC that can function as a USB host. Write firmware that copies data from one flash drive to another.

Title: Re: WinUSB now supports isochronous transfers (Windows 8.1 and later)
Post by: Tsuneo on November 21, 2013, 11:04:08 pm

Get back to the original post,

WinUsb_WriteIsochPipe(Asap) takes a "transfer", and it splits the "transfer" into transactions of MPS (Max Packet Size), like bulk/interrupt transfer.

Quote

http://msdn.microsoft.com/en-us/library/windows/hardware/dn265568(v=vs.85).aspx

WinUsb_WriteIsochPipe packetizes the transfer buffer so that in each interval, the host can send the maximum bytes allowed per interval.

On the other hand, WinUsb_ReadIsochPipe(Asap) takes USBD_ISO_PACKET_DESCRIPTOR array, like orthodox Isoc API implementation, which allows different size of each packet (transaction).

This MPS restriction of WinUsb_WriteIsochPipe(Asap) is not practical for Audio/Video applications. I'm not sure, why MS WinUSB team would decide this asymmetry.

I believe they should add WinUsb_WriteIsochPipe(Asap)Ex soon, at the next revision ;-)

Tsuneo

Title: Re: WinUSB now supports isochronous transfers (Windows 8.1 and later)
Post by: Jan Axelson on November 22, 2013, 10:19:22 am

Maybe so they can say it support isochronous even if it's not full support...