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2004-11-10 by peterburdine
Does anyone have a good way to generate the timings for the CAN bus? I've tried to do some of the math by hand, but I can't seem to ever get it right. What I'm looking for is 125k/s @ 60MHZ, 125k/s @ 48MHz and 1M/s @ 60 MHz. Thanks for any help you can give. --Peter
2004-11-11 by zarozaro
I think the equation is: CANBaudRate=pclk/(16*(BTR+1)) or BTR=pclk/(16*CANBaudRate) -1 where BTR are bits 0-9 in CANBTR register. Zaro --- In lpc2000@yahoogroups.com, "peterburdine" <lordofdawn@h...> wrote: > > Does anyone have a good way to generate the timings for the CAN bus? > I've tried to do some of the math by hand, but I can't seem to ever > get it right. > > What I'm looking for is 125k/s @ 60MHZ, 125k/s @ 48MHz and 1M/s @ 60 MHz.
> > Thanks for any help you can give. > > --Peter
2004-11-11 by peterburdine
What you described looks very similar to the UART equation. CAN is much more complex than that. First you need the baud rate prescaler to get the can clock, then you need to define SJW (syn jump width), then TSEG1 and TSEG2 to get the correct baud rate (see pg 197 in um). I've tired using some to values that Xanalyser gave me, but none of them seem to work. It was much easier to get it to work on the atmel 8051 can uc. --Peter --- In lpc2000@yahoogroups.com, "zarozaro" <zarozaro@y...> wrote:
> > I think the equation is: > > CANBaudRate=pclk/(16*(BTR+1)) > or > BTR=pclk/(16*CANBaudRate) -1 > > where BTR are bits 0-9 in CANBTR register. > > Zaro > > --- In lpc2000@yahoogroups.com, "peterburdine" <lordofdawn@h...> > wrote: > > > > Does anyone have a good way to generate the timings for the CAN > bus? > > I've tried to do some of the math by hand, but I can't seem to ever > > get it right. > > > > What I'm looking for is 125k/s @ 60MHZ, 125k/s @ 48MHz and 1M/s @ > 60 MHz. > > > > Thanks for any help you can give. > > > > --Peter
2004-11-11 by Gus
Peter, Here is a link to a free CAN baud rate calculator. It is made for Microchip products but you can use the graphs to figure out what are the possible baud rates and all other can-bits parameters. http://www.intrepidcs.com/mcp2510/ Gus --- In lpc2000@yahoogroups.com, "peterburdine" <lordofdawn@h...> wrote: > > Does anyone have a good way to generate the timings for the CAN bus? > I've tried to do some of the math by hand, but I can't seem to ever > get it right. > > What I'm looking for is 125k/s @ 60MHZ, 125k/s @ 48MHz and 1M/s @ 60 MHz.
> > Thanks for any help you can give. > > --Peter
2004-11-11 by Gus
Peter, Here is a link to a free CAN baud rate calculator. It is made for Microchip products but you can use the graphs to figure out what are the possible baud rates and all other can-bits parameters. http://www.intrepidcs.com/mcp2510/ Gus --- In lpc2000@yahoogroups.com, "peterburdine" <lordofdawn@h...> wrote: > > Does anyone have a good way to generate the timings for the CAN bus? > I've tried to do some of the math by hand, but I can't seem to ever > get it right. > > What I'm looking for is 125k/s @ 60MHZ, 125k/s @ 48MHz and 1M/s @ 60 MHz.
> > Thanks for any help you can give. > > --Peter
2004-11-11 by Hans Dornaus
Hi, Try this link below. I have just done this myself. I came up with the following number and was able to communicate on the workbench. I have still do some more studing about this very important subject. CANBitrate250k_60MHz 0x001D0007 http://www.esacademy.com/faq/calc/sja1000.htm
-----Original Message-----
From: Gus [mailto:gus_is_working@...]
Sent: Friday, 12 November 2004 1:05 AM
To: lpc2000@yahoogroups.com
Subject: [lpc2000] Re: CAN Timing and BTR
Peter,
Here is a link to a free CAN baud rate calculator. It is made for
Microchip products but you can use the graphs to figure out what are
the possible baud rates and all other can-bits parameters.
http://www.intrepidcs.com/mcp2510/
Gus
--- In lpc2000@yahoogroups.com, "peterburdine" <lordofdawn@h...>
wrote:
>
> Does anyone have a good way to generate the timings for the CAN
bus?
> I've tried to do some of the math by hand, but I can't seem to ever
> get it right.
>
> What I'm looking for is 125k/s @ 60MHZ, 125k/s @ 48MHz and 1M/s @
60 MHz.
>
> Thanks for any help you can give.
>
> --Peter
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[Non-text portions of this message have been removed]2004-11-12 by Gus
Maybe it is fixed now but I tried that SJA1000 calculator last year and it gave me wrong results. Gus --- In lpc2000@yahoogroups.com, "Hans Dornaus" <hans@c...> wrote: > Hi, > > Try this link below. I have just done this myself. I came up with the > following number and was able to communicate on the workbench. I have still > do some more studing about this very important subject. > > CANBitrate250k_60MHz 0x001D0007 > > http://www.esacademy.com/faq/calc/sja1000.htm > > > -----Original Message----- > From: Gus [mailto:gus_is_working@y...] > Sent: Friday, 12 November 2004 1:05 AM > To: lpc2000@yahoogroups.com > Subject: [lpc2000] Re: CAN Timing and BTR > > > > Peter, > > Here is a link to a free CAN baud rate calculator. It is made for > Microchip products but you can use the graphs to figure out what are > the possible baud rates and all other can-bits parameters. > > http://www.intrepidcs.com/mcp2510/ > > > Gus > --- In lpc2000@yahoogroups.com, "peterburdine" <lordofdawn@h...> > wrote: > > > > Does anyone have a good way to generate the timings for the CAN > bus? > > I've tried to do some of the math by hand, but I can't seem to ever > > get it right. > > > > What I'm looking for is 125k/s @ 60MHZ, 125k/s @ 48MHz and 1M/s @ > 60 MHz. > > > > Thanks for any help you can give. > > > > --Peter > > > > > Yahoo! Groups Sponsor > > Get unlimited calls to > > U.S./Canada > > > > > ------------------------------------------------------------------- --------- > -- > Yahoo! Groups Links > > a.. To visit your group on the web, go to: > http://groups.yahoo.com/group/lpc2000/ > > b.. To unsubscribe from this group, send an email to: > lpc2000-unsubscribe@yahoogroups.com > > c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
> > > > > [Non-text portions of this message have been removed]
2004-11-12 by mahlerweb
Hi, I've just uploaded the Application Node AN97046 which describes the how the bittiming registers are determined for a SJA1000 to the files section. In the LPC2xxx works the same CAN-core. The main difference is, that the clock is derivated from the VPB-clock, not from the crystal- oscillator. For more information see the Bosch CAN 2.0 spec. http://www.can.bosch.com/docu/can2spec.pdf --- In lpc2000@yahoogroups.com, "Gus" <gus_is_working@y...> wrote: > > Maybe it is fixed now but I tried that SJA1000 calculator last year > and it gave me wrong results. > > Gus > --- In lpc2000@yahoogroups.com, "Hans Dornaus" <hans@c...> wrote: > > Hi, > > > > Try this link below. I have just done this myself. I came up with > the > > following number and was able to communicate on the workbench. I > have still > > do some more studing about this very important subject. > > > > CANBitrate250k_60MHz 0x001D0007 > > > > http://www.esacademy.com/faq/calc/sja1000.htm > > > > > > -----Original Message----- > > From: Gus [mailto:gus_is_working@y...] > > Sent: Friday, 12 November 2004 1:05 AM > > To: lpc2000@yahoogroups.com > > Subject: [lpc2000] Re: CAN Timing and BTR > > > > > > > > Peter, > > > > Here is a link to a free CAN baud rate calculator. It is made for > > Microchip products but you can use the graphs to figure out what > are > > the possible baud rates and all other can-bits parameters. > > > > http://www.intrepidcs.com/mcp2510/ > > > > > > Gus > > --- In lpc2000@yahoogroups.com, "peterburdine" <lordofdawn@h...> > > wrote: > > > > > > Does anyone have a good way to generate the timings for the CAN > > bus? > > > I've tried to do some of the math by hand, but I can't seem to > ever > > > get it right. > > > > > > What I'm looking for is 125k/s @ 60MHZ, 125k/s @ 48MHz and > 1M/s @ > > 60 MHz. > > > > > > Thanks for any help you can give. > > > > > > --Peter > > > > > > > > > > Yahoo! Groups Sponsor > > > > Get unlimited calls to > > > > U.S./Canada > > > > > > > > > > ------------------------------------------------------------------ -
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