Re: [usb] Ask a help on

[Rudolf Usselmann <rudi@asics.ws>]

On Sun, 2003-01-12 at 12:52, nihq@red.semi.ac.cn wrote:
> Dear expert:
> 
>      I cannot understand How the usb_vbus_pad_i (Vcc of USB
> connector) of UTMI interface effect the attached flag.
> 
>      I look look through the usbf_utmi_ls.v and find that if Vcc (
> here is usb_vbus) is always logic "1", then the the machine state is 
> always in powon or reset state.
> 
> always @(posedge clk or negedge rst)
> 	if(!rst)		state <= #1 POR;
> 	else
> 	if(usb_vbus)		state <= #1 POR;
> 	else			state <= #1 next_state;
> 
>     But you know the usb_vbus (Vcc) is always logic "1" when the
> usb connector is powered. Then the usb_core will never work to 
> the useful state. 
>     Could any expert give me a hint?
> 
>     Thank Vikas T Rao for your previous answer!
> 
> best regards
> NI haiqiao

This was supposed to be an inverted input.

Alternatively the line status FSM should be rewritten
in a way that it does not need VBUS ...


rudi
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