usb info

[stack0]

just started on USB 101 with some things still not clear to me. What are the host controller transfer types versus the type of handshaking used for the input data to the MCU FIFOs?. i.e., If input data to MCU is sync. or asyns , how that affects what type of host transfer, interrupt/bulk (sync. or async.) , used in the transfer of data from the host controller to the application?. Could not locate a clear document with a table that clearly summarizes this.

 

[KlausST]

Hi,

Please clarify:
Are you referring to the Cypress USB 101 document AN57294?

Generally the slave - using it's Device descriptor (in detail: Endpoint descriptor) - determines which protocol is used.

Klaus

 

[stack0]

descriptor specifies whether endpoint is interrupt or bulk not whether it is sync or async. how the choice of async/sync at the micro controller and at the host controller are associated with choice of interrupt or bulk?. can i use async or sync for my FPGA input data to the MCU buffers and using sync or async when reading the same data from the host controller?. if data to MCU buffers are in aync mode, the data read from the host controller has to follow the async mode?? Let's assume the endpoint is bulk.

 

[KlausST]

Hi,

Still unclear. Sometimes you talk about the host somtimes about FPGA and microcontroller .. both are somehow "behind the endpoint" and thus are in different layers.

Please explain and show a drawing with description.

Klaus

 

[stack0]

if transmission to device endpoint is in sync mode, can the read out from it at user not kernel level to be done in different mode like in async mode?. If still unclear, then may be my question is out of topic.