Post by thread:CAN bus

A while ago, Brian Boles wrote: > BTW, we at Microchip are investigating Fieldbusses because we are > considering doing a CAN bus micro. If any of you have interest in CAN > bus or any Fieldbus for that matter, please let us know. From a commercial point of view, I think it is a good idea. CAN is quickly becoming very popular, at least in Europe. Personally, I'm a little sceptic about CAN: It is slow and has lots of overhead for short messages. For 1-byte messages, the overhead is 85%, so it will be very hard to get even 150 kbit/s effective bandwidth. But it is a standard... When you design a CAN interface, try to avoid one problem that both the Intel and Philips circuits suffer from. Make sure that the user can *control the number of retransmissions*! This is important for using CAN as a (hard) realtime systems bus. CAN has several properties that makes it suitable as such a bus, but indeterminism of retransmissions detroys the realtime properties. Good luck to the engineer who designs (and debugs) the unit. ;-) Martin Nilsson http://www.sics.se/~mn/ Swedish Institute of Computer Science E-mail: spam_OUTmnTakeThisOuTsics.se Box 1263, S-164 28 Kista Fax: +46-8-751-7230 Sweden Tel: +46-8-752-1574

I had a chat with the Microchip FAE in Ohio, and he said that the PIC16C185 in the future products guide omitted the minor detail that it is a CAN part. He indicated that it is due quarter 4 in 98. Just a note, not that I have done much other than hooking up off the shelf Devicenet stuff, some chips don't do all baud rates, and some have a limitted message handling capability. The ODVA spec mentions a little bit about these pitfalls. Chris Eddy pioneermicro.nb.net WF AUTOMACAO wrote: > Recently i have tested the CAN bus in a COP8, and i was curious > if someone have implemented for the PIC! > > Thank's! > > mIGUEL.

A slight deviation from the original topic... I have about a dozen instruments with RS232C/D interfaces and one PC with one serial port. Is there an easy and cheap network that can be inserted between the PC and instruments to allow addressing and multidrop configuration. If not, i plan to implement a PIC based packet network to connect all instruments, configuration as follows: [RS484 Half or Full Duplex Backbone] PCSERIAL---NODEMASTER--------------------------------------- (ADDR 00) | | | | SLAVE SLAVE SLAVE SLAVE (01) (02) (03) (nn) RS232 RS232 RS232 RS232 [INSRUM] [INSTRUM] [INSTRUM] [INSTRUM] Rather than reinvent the wheel so to speak, can any one suggest a solution. Nino Benci ****************************************************** * Antonio (Nino) Benci * * Electronics & Computing Services Manager * * Monash University - Dept of Physics * * Wellington Rd, Clayton. 3168 * * Victoria, Australia. * * TEL - 61 3 9905 3649, FAX - 61 3 9905 3637 * * EMAIL - .....nino.benciKILLspam@spam@sci.monash.edu.au * * WWW - http://www.physics.monash.edu.au/services/ews.html * ******************************************************

In a message dated 24/11/97 19:29:26, you write: << Recently i have tested the CAN bus in a COP8, and i was curious if someone have implemented for the PIC! >> mIGUEL Wait until 2Q98 they are bring out pic with CAN interface (needs power section external) the explaind in seminar last month. I think CAN is too fast for standard PIC but sombody will corect me if wrong . Good protocol been looking at it myself Phillips do good books on subject. mIGUEL mODE oN cHEERS sTEVE..... Miguel Mode Off Well I had to make it understandable to those of frail keyboard......

Wouldn't easy and cheap be just using the RS232 existing? Tie PC TX to all instr's RX thru resistors, and similar with PC RX; then just do the typical "don't speak unless spoken to" protocol you sketched. Works fine for simple things. {Quote hidden}>A slight deviation from the original topic... > >I have about a dozen instruments with RS232C/D interfaces and one PC >with one serial port. Is there an easy and cheap network that can be >inserted between the PC and instruments to allow addressing and >multidrop configuration. If not, i plan to implement a PIC based >packet network to connect all instruments, configuration as follows: > > > [RS484 Half or Full Duplex Backbone] >PCSERIAL---NODEMASTER--------------------------------------- > (ADDR 00) | | | | > SLAVE SLAVE SLAVE SLAVE > (01) (02) (03) (nn) > RS232 RS232 RS232 RS232 > [INSRUM] [INSTRUM] [INSTRUM] [INSTRUM] > >Rather than reinvent the wheel so to speak, can any one suggest a >solution. > >Nino Benci > > >****************************************************** >* Antonio (Nino) Benci * >* Electronics & Computing Services Manager * >* Monash University - Dept of Physics * >* Wellington Rd, Clayton. 3168 * >* Victoria, Australia. * >* TEL - 61 3 9905 3649, FAX - 61 3 9905 3637 * >* EMAIL - nino.benciKILLspamsci.monash.edu.au * >* WWW - http://www.physics.monash.edu.au/services/ews.html * >****************************************************** > > Bruce Cannon Style Management Systems Remember: Electronics is changing your world...for good!

Hi, I'm facing some problems with CAN Bus. first of all I'd like to know where can I find more information about CAN? Second, let me explain what's happening. I'm developing my first CAN node. I have made a program that gets some information from serial port and send it through CAN bus. I'm using a PIC18F248 and a MCP2551 transceiver. I have made 2 nodes exactly the same.What I could verify was: If I put my module in loopback mode, I can see at RX buffer everything I put in TX buffer. In normal mode, using a scope, I can see that CANRX receive everything I put in CANTX (PIC side) still in normal mode I can see at the CAN Bus line the same information I have at CANTX, but at the other node (after the transiver) I have nothing in CANRX. Could someone explain me what's happening and (if) what I'm doing wrong? Thanks in advance, Aryldo G Russo Jr. -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Here is a link to a website which has a CAN tutorial. http://www.esacademy.com/myacademy/ In addition you might want to try some of the Dearborn Technology group tools to help with the troubleshooting. http://www.dgtech.com I took their CAN class a couple of years ago, it was very good. Are you sure the CAN Bus you are connecting to is terminated properly at both ends? Susan --- Dinho <.....agrjKILLspam.....AES.COM.BR> wrote: > Hi, > > I'm facing some problems with CAN Bus. first of all > I'd like to know > where can I find more information about CAN? > __________________________________ Do you Yahoo!? Yahoo! SiteBuilder - Free, easy-to-use web site design software http://sitebuilder.yahoo.com -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Microchip have a lot of info on can on their website. ----- Original Message ----- From: "Dinho" <EraseMEagrjspam_OUTTakeThisOuTAES.COM.BR> To: <PICLISTspam_OUTMITVMA.MIT.EDU> Sent: Tuesday, July 22, 2003 1:32 PM Subject: CAN Bus {Quote hidden}> Hi, > > I'm facing some problems with CAN Bus. first of all I'd like to know > where can I find more information about CAN? > > Second, let me explain what's happening. I'm developing my first CAN > node. I have made a program that gets some information from serial port > and send it through CAN bus. I'm using a PIC18F248 and a MCP2551 > transceiver. I have made 2 nodes exactly the same.What I could verify was: > > If I put my module in loopback mode, I can see at RX buffer everything I > put in TX buffer. > In normal mode, using a scope, I can see that CANRX receive everything I > put in CANTX (PIC side) > still in normal mode I can see at the CAN Bus line the same information > I have at CANTX, but at the other node (after the transiver) I have > nothing in CANRX. > > Could someone explain me what's happening and (if) what I'm doing wrong? > > Thanks in advance, > > Aryldo G Russo Jr. > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

I just found some datasheets and 3 Application Notes from Microchip. I have also the Bosch specification. I'm looking for some more general. I found some books, but the freight(to Brazil) is almost the same price of the book. does anyone have some more information in PDF or something like that to send me in PVT? Thanks Dinho gtyler wrote: >Microchip have a lot of info on can on their website. > >{Original Message removed}

www.can.bosch.com/ Dinho <@spam@agrjKILLspamAES.COM.BR> skrev den Tue, 22 Jul 2003 16:20:48 -0300: {Quote hidden}> I just found some datasheets and 3 Application Notes from Microchip. I > have also the Bosch specification. I'm looking for some more general. I > found some books, but the freight(to Brazil) is almost the same price of > the book. does anyone have some more information in PDF or something > like that to send me in PVT? > > Thanks > > Dinho > > gtyler wrote: > >> Microchip have a lot of info on can on their website. >> >> {Original Message removed}

www.can-cia.de/downloads/specifications/ Dinho <KILLspamagrjKILLspamAES.COM.BR> skrev den Tue, 22 Jul 2003 16:20:48 -0300: {Quote hidden}> I just found some datasheets and 3 Application Notes from Microchip. I > have also the Bosch specification. I'm looking for some more general. I > found some books, but the freight(to Brazil) is almost the same price of > the book. does anyone have some more information in PDF or something > like that to send me in PVT? > > Thanks > > Dinho > > gtyler wrote: > >> Microchip have a lot of info on can on their website. >> >> {Original Message removed}

Dinho wrote: > Hi, > > I'm facing some problems with CAN Bus. first of all I'd like to know > where can I find more information about CAN? > > Second, let me explain what's happening. I'm developing my first CAN > node. I have made a program that gets some information from serial port > and send it through CAN bus. I'm using a PIC18F248 and a MCP2551 > transceiver. I have made 2 nodes exactly the same.What I could verify was: > > If I put my module in loopback mode, I can see at RX buffer everything I > put in TX buffer. > In normal mode, using a scope, I can see that CANRX receive everything I > put in CANTX (PIC side) > still in normal mode I can see at the CAN Bus line the same information > I have at CANTX, but at the other node (after the transiver) I have > nothing in CANRX. > > Could someone explain me what's happening and (if) what I'm doing wrong? I used to have that problem a lot when I first stated with CAN. Can't remember what all caused it, seemed like most anything would cause that behavior. At one point I had an extrememly fine solder bridge across TX and RX that I could only see with a microscope. That messed everything up. I also found that with short line lengths (~6") termination actually made things worse. Check your software very carefully, and go over the errata sheet. Sorry I'm not much help, maybe ill remember more in the morning. -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics