baud detection thru S/W in devicenet CAN

Hello 
can any body help me with an idea ,for detection of baud in devicenet
thru software which runs in the slave module
Regards
PMM

pmm <muralipmanohar@hotmail.com> wrote:
> Hello 
> can any body help me with an idea ,for detection of baud in devicenet
> thru software which runs in the slave module

I doubt that's possible at all, ultimately.  

CAN is quite universally handled by dedicated hardware controllers, so
if you want autodetection of baud rates to work well, it should be
handled (or at least supported) by your CAN controller, too.

If your particular hardware doesn't support auto-bauding at all,
you'll have no symptoms left for software auto-detection to work wih
besides the single-bit result of "go, or no go?"

This leaves only brute-force trial and error: watch your CAN
controller: if it quickly runs into bus-off state for exceeding its
error counts, odds are that's happening because the currently selected
baudrate is wrong.  Choose a different one.  Repeat until you
successfully receive messages.

-- 
Hans-Bernhard Broeker (broeker@physik.rwth-aachen.de)
Even if all the snow were burnt, ashes would remain.

On 2004-05-05, Hans-Bernhard Broeker <broeker@physik.rwth-aachen.de> wrote:

>> can any body help me with an idea ,for detection of baud in
>> devicenet thru software which runs in the slave module

> This leaves only brute-force trial and error: watch your CAN
> controller: if it quickly runs into bus-off state for exceeding its
> error counts, odds are that's happening because the currently selected
> baudrate is wrong.  Choose a different one.  Repeat until you
> successfully receive messages.

That's how it's done.  Put the CAN controller into listen-only
mode. Then cycle through the three baud rates until you receive
valid messages.

-- 
Grant Edwards                   grante             Yow!  I have many CHARTS
                                  at               and DIAGRAMS...
                               visi.com            

pmm wrote:

> Hello
> can any body help me with an idea ,for detection of baud in devicenet
> thru software which runs in the slave module
> Regards
> PMM

Mr Koppe talked about technical solutions at the 9th International CAN
Conference.

Regards
 Heinz

"pmm" <muralipmanohar@hotmail.com> wrote in message
news:1f1fe31f.0405042046.333fbddc@posting.google.com...
> Hello
> can any body help me with an idea ,for detection of baud in devicenet
> thru software which runs in the slave module
> Regards
> PMM

There is a Philips Application Note (AN97076) that describes
(among other things) a method of automatic bit-rate detection
with the SJA1000 CAN controller.  See section 5.6.

http://www.semiconductors.philips.com/acrobat/applicationnotes/AN97076.pdf

 -- Kevin