| Author |
Topic |
|
|
3963
85 Posts |
 Posted - 21 Aug 2002 : 16:53:14
|
Hi all,
I was wondering if anyone has encountered an odd USB error:
Control Out messages to the slave larger than 0x2000 (8192 bytes) in size are corrupted in odd ways (blocks of 1000 are repeated, etc). I checked my data before and after the IssueVendorTransfer CE primitive and it looks good. The slave is implemented via the Cypress EZ-USB FX chip, so it can only handle data in 64 byte chunks, making it unlikely that the problem is there (Unfortunately, without a USB bus snooper, I can't say with certainty). The Control-IN messages work fine to the 64 kB limit.
CE version: ADS 3.33 10MB load
Any thoughts? |
|
|
tempo
26 Posts |
Posted - 21 Aug 2002 : 20:28:39
|
I thought USB had a limit of 8192 bytes (courtesy of CE driver).
|
 |
|
|
3963
85 Posts |
Posted - 22 Aug 2002 : 10:18:20
|
Holy smokes! You're right! From the DDK ref:
"Note: Windows CE 2.10 and later have limits on the amounts of data per transfer. All data transfers using USBDI transfer functions are limited to 8K of data per transfer, due to an internal limitation in Microsoft’s USB implementation. If you are porting USB client drivers from Microsoft Windows NT, Windows 95 or Windows 98, you may need to make changes in your code to enforce a limit of 8K per transfer."
Thanks, tempo!
|
|
|
| |
Topic |
|
|
|
All Forums
Microsoft Windows CE
[GM] USB Ctrl out size limit?
Forum Locked
Send Topic to a Friend
Printer Friendly