About USB HS AND FS detection ?

[quan228228]

hi,all

When in USB2.0 detection process. First, Devie sends a chirp K, then after hundreds of ns, Device will detect KJKJKJ. If detected, then go to HS mode, otherwise go into FS mode.

I want to know, who and why sends KJKJKJ, Device or Host?


Thanks in advance!

/David

 

[vcnvcc]

Its Device Who Sends First K to HOST, after defined duration of time HOST sends KJ KJ KJ 3 times to device, If Device detects it properly enters into HS otherwise FS.

Check it out with Data sheet, all waveforms are given..

 

[quan228228]

The part of UTMI 2.0 spec:
If the downstream port is a not HS capable, then the HS k asserted by the device is ignored and the alternating sequence of HS chirp's K and j's is not generated.
If the downstream port is HS capable then it will begin generateing an alternaing sequence of Chirp K's and Chirp J's after the termination of the chirp from the device.

I don't understand that how the host know the downstream port is HS capable or FS capable?

Thanks.

David

 

[quan228228]

help me?


/David

 

[vcnvcc]

Now question is how the host know the downstream port is HS capable or FS capable?

we are connecting the device to host via hub, and hub may be 1.1 compatible or 2.0

from this host will come to know.

now say in host - driver loaded is 2.0 compatible
hub connected to it is 1.1 compatible
n u r connecting HS device, it will work but will work as FS device.

still u just go through this pdf of UTMI.

 

[quan228228]

Thanks!

 

[poluekt]

Hello!
At HS-mode after host chirp ended i see that second bus reset appeared. Is it correct?

 

[poluekt]

It's not correct. I used shorten-time simulation, for full-time simulation no problem.