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Date: Sun, 31 Jan 2010 10:28:45 +0100
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To: Theodore Kilgore <kilgota@banach.math.auburn.edu>
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Subject: Re: PAC7302 short datasheet from PixArt
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Hi,
Theodore Kilgore wrote:
> 
> On Sat, 30 Jan 2010, Németh Márton wrote:
> 
>> Hi,
>>
>> if anyone interested there is a brief overview datasheet about
>> PixArt PAC7301/PAC7302 at
>> http://www.pixart.com.tw/upload/PAC7301_7302%20%20Spec%20V1_20091228174030.pdf
>
> [...]
>
> Now, as to the substance of the mail above, thanks a lot. I had a bunch of 
> the PixArt datasheets already, but I had missed that one. I would have a 
> question, though:
> 
> This datasheet gives a lot of information about pinouts on the sensor chip 
> and such good stuff which might be useful if one were constructing a 
> circuit board on which to put the chip. What it does not give, very 
> unfortunately, is any information about the command set which needs to be 
> sent across the USB connection, which in turn actuates the circuits which 
> in turn sends something to the sensor across one of those pins. For 
> example, to set green gain one has to do something on connector X. But how 
> does one send a command from the computer which does something on 
> connector X? Some other datasheets from some other companies (Omnivision, 
> for example) do seem occasionally to provide such information.
> 
> Thus, a question for you or for anyone else who reads it:
> 
> Has anyone figured out any shortcuts for matching up the missing pieces of 
> information? Probably the answer is "no" but I think this is the kind of 
> question which is worth asking again on some periodic basis.

I have created some notes about my experiments, but they are only based on
trial-and-error. I started to created a PixArt PAC7301/PAC7302 Wiki page
this morning but the communication protocol details I could found out is
not yet finished. The page can be found at
http://linuxtv.org/wiki/index.php/PixArt_PAC7301/PAC7302 .

I hope I'll have the time to add a section about the communication protocol
details I could find out from the current gspca_pac7302 driver source code
and my experiments.

Regards,

	Márton Németh