Hi,
I am working on USB driver for the 4G driver. I want to understand what all
types of USB transfer are there and what is the best creteria to select a
transfer type for the USB.
If anyone can summarize and point me to the articles it will be good.
Regards,
Rabish
Use bulk transfer.
>I am working on USB driver for the 4G driver. I want to understand what all types of USB transfer are
Control: short req/resp transactions. No timing guarantees.
Bulk: long TCP-style pipes, the least traffic priority of these 4 types, no timing guarantees. If the data is not ready - the transfer is suspended till the next USB timeframe.
Interrupt: short packets with latency guarantee.
Isochronous: a frame of data per USB timeframe (strict timing), if the data is not ready to this timeframe it is filled with junk (no flow control like for Bulk).
there and what is the best creteria to select a transfer type for the USB.
You should select one supported by your hardware target.
The modem probably implements the CDC (serial over USB) spec.
Some modems like ADSL ones, instead, implement the the Ethernet card spec (maybe RNDIS) and require the host to run PPPoE on top of them.
–
Maxim S. Shatskih
Microsoft MVP on File System And Storage
xxxxx@storagecraft.com
http://www.storagecraft.com
On Aug 16, 2014, at 7:28 AM, Ravish Yadav > wrote:
I am working on USB driver for the 4G driver. I want to understand what all types of USB transfer are there and what is the best creteria to select a transfer type for the USB.
If anyone can summarize and point me to the articles it will be good.
You need to find some books about USB. The software parts of the freely available USB spec itself are quite readable.
There are four types of endpoints ? your choice depends on what kinds of transfers you are doing. Bulk is often the best choice.
–
Tim Roberts, xxxxx@probo.commailto:xxxxx
Providenza & Boekelheide, Inc.</mailto:xxxxx>