usb bulk transfer lost
Hi!
You must provide some more details about that situation...
How exactly your device is missing ? Just missed some packet or is entirely lost from USB bus ?
Are you sure that the USB camera use Bulk ? It's not typical for real video & audio ...
Also if it is Bulk then this MUST NOT disturb your device ! By USB specification Bulk transfers are performed ONLY when there is enough BUS free bindwidth, so you must not receive any video or audio if your Isohronous device sends much data...
However I think camera use Isohronous also... So What is happened we you cannect your device (there is nothing else on the USB bus) ... Host ask your device for required Iso data ... USB spec. 5.6.1 says
"An endpoint in a given configuration for an isochronous pipe specifies the maximum size data payload that it can transmit or receive. The USB System Software uses this information during configuration to ensure that there is sufficient bus time to accommodate this maximum data payload in each (micro)frame. If there is sufficient bus time for the maximum data payload, the configuration is established; if not, the configuration is not established."
So, it'll be ok cause all bandwidth is free now...
Now you connect 2-nd device... If it is Bulk - there must not be problem ... Isohronous take precedence over Bulk and your device will continue to work properly...
If 2-nd device use Iso again - that problem occurs... By specification HOST must discard second device configuration if no enough bandwidth, BUT it's also possible Host to decide to ask devices again for alternative configuration to fit their requirements... and I think that here actually your device lose the bandwidth... You can debug it and check does HOST assing you new configuration ?
Also, it's possible these dropped packets to be lost due to CRC error for example!
How much packets have been lost ?
Regards !
And don't forget helped me button if I helped you