Re: [usb] About nibble mode in USB Transceiver

[Ravi Kumar <ravikumar_vlsi@yahoo.co.in>]

hi all,
Would some pls clarify the operation of usb mouse 
suppose when i change the coordinate information of
the mouse by moving the mouse pointer to different
location , what will be the physical ( Electrical
change ) .

what way exactly thru hub, the host polls the mouse
device & understand the change in coordinate

pls clarify
Regards
Ravikumar




 --- Vikas T Rao  <vikasraot@myw.ltindia.com> wrote: >
** Proprietary **
> 
> hi Jiang,
> 
> i don't know much about the UTMI spec. but as far as
> my knowledge on bit unstuffing is concerned,
> 
> the bit unstuffer will first unstuff the serial data
> input and pass on the unstuffed data to the serial
> to parallel converter. also the bit unstuffer should
> have some extra control signal to indicate that the
> present bit is an unstuffed bit or not. say, in ur
> example that control signal should be high only
> during the 7th receiving bit('0'). when the
> serial-to-parallel converter receives the unstuffed
> serial input from bit unstuffer, it should check if
> the control signal is high or not at any point of
> time. if it's not high, then it will convert the
> serial input into nibble in four clock pulses. else
> it should wait for another clock pulse(a total of 5
> clock pulses) if the control signal is high.
> 
> generally the above design is better but it's upto
> one to follow one's own.
> 
> hope u have understood.
> 
> ....Vikas.
> 
> >>> jiangdaosan@21cn.com 06/25/02 08:14AM >>>
> Hi,all:
>    I have a question in the nibble mode in USB
> Transceiver design.
>    In the USB Transceiver Module
> Specification(v1.04), there is a little about 
> nibble mode referred to in Page 10:
> "For instance, serial data may be converted to a
> nibble-wide parallel format
> immediately and handled as 4-bits data between the
> HS DLL and the RX Hold Register"
> But as the bit unstuffer detected the sequence "1 1
> 1 1 1 1 0" and remove the last bit
> "0", How can the bit unstuffer realized in the
> nibble-wide parallel format? and 
> how to output parallel data correctly according the
> spec? I was so puzzled about it.
> 
> Can anybody help me ?   thanks in advance.
> Any comments and advice are welcomed!
> 
> 
> 
> Best Regards.
> 
> ================================
> Jiang Daosan jiangdaosan@21cn.com 
> Institute of RF & OE IC 
> Southeastern University
> NanJing Jiangsu China(210096)
> Tel: 08625-3793303--8005
> http://iroi.seu.edu.cn/ 
> ================================
> 
> 
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