RE: MilCAN processors

I have an Agilent Waveform Generator.  I can trigger on the start bit and 
have it create an error flag of 6 bits to destroy the packet.  If there is 
a one shot mode then we should not see a retry.  If I don't damage the 
packet then it will only show up once.

And if it turns out only the SJA 1000 will do the job then that's what 
I'll use.  Just trying for the lowest cost option here.

John Dammeyer

"ELS! The Solution"
Automation Artisans Inc.
http://www.autoartisans.com/ELS/
Ph. 1 250 544 4950


> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On
> Behalf Of Kees Zagers
> Sent: Thursday, December 20, 2012 1:45 AM
> To: [email protected]
> Subject: Re: [CANLIST] MilCAN processors
>
>
> Hello John,
>
> In the SJA1000 datasheet it is not "undocumented", however
> only as a remark in a small font, unreadable for people over 50 :-(
>
> I'm also working on the PIC32 controllers now and did not
> find in the documentation that a single-shot transmission is
> possible; let us give it a try.
>
> Kees
>
>
> ----- Original Message ----- 
> From: "John Dammeyer" <[email protected]>
> To: <[email protected]>
> Sent: Thursday, December 20, 2012 10:27 AM
> Subject: RE: [CANLIST] MilCAN processors
>
>
> >
> > Thanks Kees,
> >
> > Interesting undocumented feature.  I wonder if the PIC ECAN
> will do that?
> > I'll do some research and report back.
> >
> > I do agree with Wim that an ERROR FRAME should be allowed but
> > re-transmissions should be prevented for MilCAN.
> >
> > John Dammeyer
> >
> >
> > "ELS! The Solution"
> > Automation Artisans Inc.
> > http://www.autoartisans.com/ELS/
> > Ph. 1 250 544 4950
> >
> >
> > > -----Original Message-----
> > > From: [email protected]
> > > [mailto:[email protected]] On
> > > Behalf Of [email protected]
> > > Sent: Thursday, December 20, 2012 12:26 AM
> > > To: [email protected]
> > > Subject: RE: [CANLIST] MilCAN processors
> > >
> > >
> > > Hi John, Wim,
> > >
> > > In my opinion error frames should be produced also in
> MILCAN, because
> > > everyone has to know that the message is invalid. The
> CAN-controllers
> > > should have the possibility to do a so-called "single-shot"
> > > transmission. The good-old SJA1000 controller can do that
> and I think
> > > also more modern CAN controllers. If you set TX request
> and Tx abort
> > > simultaniously a single-shot transmission is performed.
> > >
> > > Kees
> > >
> > > Stremerch, Wim schreef op 20.12.2012 07:51:
> > > > Message
> > > >
> > > > Hi John,
> > > >
> > > > Error frames are allowed on the bus, but if a controller sees an
> > > > error
> > > > frame it should not retransmit the message.
> > > >
> > > > We use a controller that supports TTCAN. In this mode
> it will not
> > > > retransmit the message when an error frame is received.
> > > >
> > > > Best regards,
> > > >
> > > > Wim Stremerch
> > > >
> > > > FROM: [email protected]
> > > > [mailto:[email protected]] ON
> BEHALF OF
> > > > John
> > > > Dammeyer
> > > > SENT: donderdag 20 december 2012 1:08
> > > > TO: 'CANLIST'
> > > > SUBJECT: [CANLIST] MilCAN processors
> > > >
> > > > Hi Everyone,
> > > >
> > > > One of the MilCAN specifications is that a node is not
> allowed to
> > > > issue an error frame to get a message retransmitted. As
> I understand
> > > > it the designers of MilCAN wanted to insure that the Sync Flag
> > > > Message
> > > > always showed up at exactly the same time. Since the number of
> > > > replies
> > > > in each sync slot are restricted only a large burst of higher
> > > > priority
> > > > messages could thwart the sync flag. And an error burst
> that caused
> > > > retries.
> > > >
> > > > For example. Imagine there is time for 20 messages between SYNC
> > > > FLAGs.
> > > > The system designer has one SYNC FLAG where there are 18 replies
> > > > leaving room for two ASYNC messages. Say 4 of the replies are
> > > > corrupted by a noise burst during the CRC. The retries would now
> > > > extend past the time point for a new SYNC FLAG and
> potentially it
> > > > would be shifted or delayed. Plus old data would show
> up in the next
> > > > SYNC Slot.
> > > >
> > > > The trouble is, there are very few CAN devices out
> there that can
> > > > have
> > > > the ERROR frame turned off. Yes, the node can go to
> listen mode but
> > > > then all messages get through including ones with invalid CRCs.
> > > >
> > > > Has anyone run into a processor family where this is
> possible? Am I
> > > > misinterpreting the MilCAN spec?
> > > >
> > > > Best Regards,
> > > >
> > > > John Dammeyer
> > > >
> > > > "ELS! The Solution"
> > > > Automation Artisans Inc.
> > > > http://www.autoartisans.com/ELS/ [1]
> > > > Ph. 1 250 544 4950
> > > >
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