[cpia] ECP transfer of data

[Greg Reynolds]

Hi,

Thanks for the info.

I got it working eventually. The problem was the negotiation to ECP/Upload
mode (status of autofeed).

I am confused as to where the UPLOAD_FLAG  0x08 is defined other than by
CPiA. In all the documentation I have come across it only shows as
'reserved'.

The DOS driver doesn't appear to implement the IEEE 1284.3/MS ECP spec.
properly (the bit on the ECP command read does not have the 'correct' status
of autofeed).  Interestingly my implementation works with the correct
status...

In the end I solved the problem with an educated trial and error approach
:).

Personally I wouldn't call it "full chip documentation" - leaves a bit to
the imagination maybe.

If anyone is interested, I am interfacing the camera to an M16C for a
line-following robot project. I will make source available for driver when
it's finished.

Cheers.

Greg.


----- Original Message -----
From: "Peter Pregler" <Peter_Pregler@email.com>
To: "J114(G.M.REYNOLDS)" <G.M.REYNOLDS@bham-eee-fs4.bham.ac.uk>
Cc: <cpia@risc.uni-linz.ac.at>
Sent: Sunday, February 24, 2002 12:38 PM
Subject: Re: [cpia] ECP transfer of data


> On Fri, Feb 22, 2002 at 03:58:36PM -0000, J114(G.M.REYNOLDS) wrote:
> >
> > I then attempt to clock data in from the camera.  All control lines
change
> > appropriately and it appears that data is coming in. However, the only
value
> > on the port is 0xFF.
> >
> > Answers to the following questions would help me:
> > 1. Is the initialisation sequence critical? I have followed it according
to
> > datasheet.
> > 2. I have attempted to use the StartDummyStream command to get back
data. It
> > also sends 0xFFs.
>
> I have never used the dummy-stream. But the 0xFF rings some bell. IIRC,
> the chip will _always_ provide you with 0xFF if you read and there is
> no data available. So double-check if you really have done the
> initialisation correctly. Sequence and even timings between sending
> commands does matter. Just have a look at the stream-read (i.e. the
> non-dma code) in cpia_pp.c.
>
> > Are there any more datasheets for the camera available?
>
> There is full chip documentation including the windows driver available
> at webcam.sourceforge.net. What more do you want?!
>
> Good luck, Peter
>
> --
> Feeling amorous, she looked under the sheets and cried, "Oh, no,
> it's Microsoft!"
> -------------------------------
> Email: Peter_Pregler@email.com