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>Part of my schematic, at least the part including the OV7640 is here : =
http://homepage.ntlworld.com/paul.olley/
Since the above webpage is still getting a significant number of hits 8 =
months later, to make the URL "permanent", I've copied the HTML to the =
following URL :
http://www.olley.com/ov7640/index.html
The original will disappear in due course.
Paul.
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charset=3Diso-8859-1">
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<BODY bgColor=3D#ffffff>
<DIV><FONT face=3DArial size=3D2>>Part of my schematic, at least the =
part=20
including the OV7640 is here : <A=20
href=3D"http://homepage.ntlworld.com/paul.olley/">http://homepage.ntlworl=
d.com/paul.olley/</A></DIV>
<DIV> </DIV>
<DIV dir=3Dltr>
<DIV>Since the above webpage is still getting a significant number =
of hits=20
8 months later, to make the URL "permanent", I've copied the HTML to the =
following URL :</DIV>
<DIV><A=20
href=3D"http://www.olley.com/ov7640/index.html">http://www.olley.com/ov76=
40/index.html</A></DIV>
<DIV> </DIV>
<DIV>The original will disappear in due course.</DIV>
<DIV> </DIV>
<DIV>Paul.</DIV></DIV></FONT></BODY></HTML>
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Reply by vinch●June 8, 20052005-06-08
Yes, that's it
I can also see the microcontroller releasing the data line, but the
the level stays the same...
Thanks for the measurements
> Paul Olleywrote
[quote:deef3a4c8b]Just another question, how long does it take fo
the camera to answe
> the read address ? I'm waiting 50us, I thought it was enough, bu
> apparently that could be the problem
>
Do you mean, "How long does it take the camera to take the SCCB dat
line
low during the acknowledge bit time? (ie : after the transmission o
the
address bits A7 to A1 and R/W?
Or do I misunderstand your question
When I looked at the ACK timing with my oscilloscope, I could clearl
see
the microcontroller releasing the data line, and the OV7640 taking th
data
line low to ack. The low voltage levels were ever so slightl
different, so
it was easy to see the timing. I will have to get the scope out agai
to
make the measurement you may be asking for
Paul.[/quote:deef3a4c8b
Reply by ●June 8, 20052005-06-08
On Wednesday, in article
<aemdnSZKApHjNDvfRVn_vg@giganews.com>
vincesusu@yahoo-dot-fr.no-spam.invalid "vinch" wrote:
>Thanks for your answers all ! and thanks for the schematic.
>
>Just another question, how long does it take for the camera to answer
>the read address ? I'm waiting 50us, I thought it was enough, but
>apparently that could be the problem.
50us from what?
From SCL set low for the ACK bit?
From SDA driven passive high?
What is the clock period for your address/data bits?
The fastest SCCB can be clocked is 100kHz, so 10us for each bit of
7 address bits, read/write bit, and ack bit, so the first address byte
is 9 x 10us = 90us MINIMUM plus start I2C timing.
If you are running at 100kHz, then wait at leat 90 if not 100us for the
whole address and ack, *IF* you are using some form of I2C controller.
If bit banging do a wait one each bit, slightly longer on ack.
You are still driving the SCL (SCCB clock) at that stage?
What frequency are you trying to drive SCCB at?
--
Paul Carpenter | paul@pcserviceselectronics.co.uk
<http://www.pcserviceselectronics.co.uk/> PC Services
<http://www.gnuh8.org.uk/> GNU H8 & mailing list info
<http://www.badweb.org.uk/> For those web sites you hate
Reply by Paul Olley●June 8, 20052005-06-08
> Just another question, how long does it take for the camera to answer
> the read address ? I'm waiting 50us, I thought it was enough, but
> apparently that could be the problem.
Do you mean, "How long does it take the camera to take the SCCB data line
low during the acknowledge bit time? (ie : after the transmission of the
address bits A7 to A1 and R/W?"
Or do I misunderstand your question?
When I looked at the ACK timing with my oscilloscope, I could clearly see
the microcontroller releasing the data line, and the OV7640 taking the data
line low to ack. The low voltage levels were ever so slightly different, so
it was easy to see the timing. I will have to get the scope out again to
make the measurement you may be asking for.
Paul.
Reply by vinch●June 8, 20052005-06-08
Thanks for your answers all ! and thanks for the schematic
Just another question, how long does it take for the camera to answe
the read address ? I'm waiting 50us, I thought it was enough, bu
apparently that could be the problem
Reply by CBFalconer●June 5, 20052005-06-05
Paul Olley wrote:
>
> >> Part 1.1 Type: Plain Text (text/plain)
> >> Encoding: quoted-printable
> >
> > Another unread message because of the html or mime encoding.
> > Usenet is a pure text mechanism.
>
> Sorry! I think it was as a result of cutting and pasting from the datasheet
> into the reply.
Misteaks happen :-) At least you are aware of the problem.
--
"If you want to post a followup via groups.google.com, don't use
the broken "Reply" link at the bottom of the article. Click on
"show options" at the top of the article, then click on the
"Reply" at the bottom of the article headers." - Keith Thompson
Reply by Paul Olley●June 5, 20052005-06-05
>> Part 1.1 Type: Plain Text (text/plain)
>> Encoding: quoted-printable
>
> Another unread message because of the html or mime encoding.
> Usenet is a pure text mechanism.
Sorry! I think it was as a result of cutting and pasting from the datasheet
into the reply.
Reply by CBFalconer●June 4, 20052005-06-04
Paul Olley wrote:
>
> Part 1.1 Type: Plain Text (text/plain)
> Encoding: quoted-printable
Another unread message because of the html or mime encoding.
Usenet is a pure text mechanism.
--
"If you want to post a followup via groups.google.com, don't use
the broken "Reply" link at the bottom of the article. Click on
"show options" at the top of the article, then click on the
"Reply" at the bottom of the article headers." - Keith Thompson
Reply by ●June 3, 20052005-06-03
On Friday, in article
<Ni%ne.2413$8m5.346@newsfe5-gui.ntli.net> may_2005@olley.com
"Paul Olley" wrote:
>This is a multi-part message in MIME format.
mutter, mutter, mutter....
>"Paul Carpenter" <paul$@pcserv.demon.co.uk> wrote in message =
>news:20050603.0854.309215snz@pcserv.demon.co.uk...
>> On Friday, in article <Q_GdnSyV3OorjD3fRVn_vg@giganews.com>
>> vincesusu@yahoo-dot-fr.no-spam.invalid "vinch" wrote:
>>>The camera is still not answering (pulling down SDA pin) even if I
>>>send 42h as write address (0100 0010). I'm recording SDA and SCL
>>
>> READ address.
>
>The datasheet reads : "The device slave addresses for the OV7640/OV7141 =
>are 42 for write and 43 for read."
Must remember when house full of builders, don't rely on another posting
double check the datasheet.
>>>Do you have a schematic of your circuit ? Can I have a look at your
>>>code ?
>
>Part of my schematic, at least the part including the OV7640 is here : =
>http://homepage.ntlworld.com/paul.olley/
>
>The FET's are level shifters since the PIC is running at 5V and the =
>OV7640 runs on 3.3V
>=20
>> I don't have FPGA code for such a setup and I have used bit banging =
>from
>> ports and Philips PCF8584 I2C controller for such tasks. There are =
>examples
>> about like fclib if you search for that as an example for Altera PLD =
>I2C
>> slave/master.
>
>My code is also on a PIC.
>
>Among many others, I read the following webpage : =
>http://www.robot-electronics.co.uk/htm/using_the_i2c_bus.htm There is =
>some C code at the bottom which I thought was quite easy to read.
>
>I didn't find Omnvision parts easy to source, in fact, I only found one =
>supplier : www.2k1.co.uk
In UK I beleive they are the only source, but I have had varying degrees
of success with that company over the years with various parts, and part
shipments.
>Where else are OV products available?
According to their website
Telecom Design Communications Ltd.
Tel: +44(0)1256 332800
Fax: +44 (0)1256 332810
Website: www.tdc.co.uk
Email: web.sales@tdc.co.uk
>Paul.
>
>
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"Paul Carpenter" <paul$@pcserv.demon.co.uk> wrote in message =
news:20050603.0854.309215snz@pcserv.demon.co.uk...
> On Friday, in article <Q_GdnSyV3OorjD3fRVn_vg@giganews.com>
> vincesusu@yahoo-dot-fr.no-spam.invalid "vinch" wrote:
>>The camera is still not answering (pulling down SDA pin) even if I
>>send 42h as write address (0100 0010). I'm recording SDA and SCL
>=20
> READ address.
The datasheet reads : "The device slave addresses for the OV7640/OV7141 =
are 42 for write and 43 for read."
>>Do you have a schematic of your circuit ? Can I have a look at your
>>code ?
Part of my schematic, at least the part including the OV7640 is here : =
http://homepage.ntlworld.com/paul.olley/
The FET's are level shifters since the PIC is running at 5V and the =
OV7640 runs on 3.3V
=20
> I don't have FPGA code for such a setup and I have used bit banging =
from
> ports and Philips PCF8584 I2C controller for such tasks. There are =
examples
> about like fclib if you search for that as an example for Altera PLD =
I2C
> slave/master.
My code is also on a PIC.
Among many others, I read the following webpage : =
http://www.robot-electronics.co.uk/htm/using_the_i2c_bus.htm There is =
some C code at the bottom which I thought was quite easy to read.
I didn't find Omnvision parts easy to source, in fact, I only found one =
supplier : www.2k1.co.uk
Where else are OV products available?
Paul.
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<META http-equiv=3DContent-Type content=3D"text/html; =
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<STYLE></STYLE>
</HEAD>
<BODY>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>"Paul Carpenter" <</FONT><A=20
href=3D"mailto:paul$@pcserv.demon.co.uk"><FONT face=3DArial=20
size=3D2>paul$@pcserv.demon.co.uk</FONT></A><FONT face=3DArial =
size=3D2>> wrote in=20
message </FONT><A =
href=3D"news:20050603.0854.309215snz@pcserv.demon.co.uk"><FONT=20
face=3DArial=20
size=3D2>news:20050603.0854.309215snz@pcserv.demon.co.uk</FONT></A><FONT =
face=3DArial size=3D2>...</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>> On Friday, in article =
<</FONT><A=20
href=3D"mailto:Q_GdnSyV3OorjD3fRVn_vg@giganews.com"><FONT face=3DArial=20
size=3D2>Q_GdnSyV3OorjD3fRVn_vg@giganews.com</FONT></A><FONT =
face=3DArial=20
size=3D2>><BR>> </FONT><A=20
href=3D"mailto:vincesusu@yahoo-dot-fr.no-spam.invalid"><FONT =
face=3DArial=20
size=3D2>vincesusu@yahoo-dot-fr.no-spam.invalid</FONT></A><FONT =
face=3DArial size=3D2>=20
"vinch" wrote:<BR></FONT></DIV>
<DIV><BR><FONT face=3DArial size=3D2>>>The camera is still not =
answering=20
(pulling down SDA pin) even if I<BR>>>send 42h as write address =
(0100=20
0010). I'm recording SDA and SCL<BR>> <BR>> READ =
address.<BR></FONT></DIV>
<DIV><FONT face=3DArial size=3D2>The datasheet reads : "</FONT><FONT =
face=3DArial=20
size=3D2>The device slave addresses for the OV7640/OV7141 are 42 for =
write and=20
</FONT><FONT face=3DArial size=3D2>43 for read."</FONT></DIV><FONT =
face=3DArial=20
size=3D2>
<DIV><BR>>>Do you have a schematic of your circuit ? Can I have a =
look at=20
your<BR>>>code ?<BR></DIV>
<DIV>Part of my schematic, at least the part including the OV7640 is =
here : <A=20
href=3D"http://homepage.ntlworld.com/paul.olley/">http://homepage.ntlworl=
d.com/paul.olley/</A></DIV>
<DIV> </DIV>
<DIV>The FET's are level shifters since the PIC is running at 5V and the =
OV7640 runs on 3.3V</DIV>
<DIV> <BR>> I don't have FPGA code for such a setup and I have =
used bit=20
banging from<BR>> ports and Philips PCF8584 I2C controller for such =
tasks.=20
There are examples<BR>> about like fclib if you search for that as an =
example=20
for Altera PLD I2C<BR>> slave/master.<BR></DIV>
<DIV>My code is also on a PIC.</DIV>
<DIV> </DIV>
<DIV>Among many others, I read the following webpage : <A=20
href=3D"http://www.robot-electronics.co.uk/htm/using_the_i2c_bus.htm">htt=
p://www.robot-electronics.co.uk/htm/using_the_i2c_bus.htm</A> =20
There is some C code at the bottom which I thought was quite easy to =
read.</DIV>
<DIV><BR>I didn't find Omnvision parts easy to source, in fact, I only =
found one=20
supplier : <A =
href=3D"http://www.2k1.co.uk">www.2k1.co.uk</A></DIV>
<DIV> </DIV>
<DIV>Where else are OV products available?</DIV>
<DIV> </DIV>
<DIV>Paul.</DIV>
<DIV> </DIV>
<DIV></FONT> </DIV></BODY></HTML>
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