Re: My device stops receiving when powered from battery
[email protected] Thu, 27 Sep 2018 15:39:51 +0200 (CEST)
| Newsgroups | gmane.comp.hardware.bus.can |
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| Message-ID | <[email protected]> |
--=_7018717f-78aa-43ee-9fb8-d0ca52af5081 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit This is when you start prodding things with a scope. The problem may be a combination of issues in different devices. Seeing that it works with a separate battery (i.e. completely floating power), the "common" ground might not be that common after all. The quickest way to solve this is seeing what is actually happening on the bus. cheers, Bram Van: "Christiano SA" <[email protected]> Aan: [email protected] Verzonden: Donderdag 27 september 2018 15:09:47 Onderwerp: Re: [CANLIST] My device stops receiving when powered from battery I am software oriented too, but perhaps you are using a regulator with Max current different of the power supply of the evaluation board. That would explain the different behavior. (There are a lot of people saying about 7805 regulator inefficiency when I've googled) Which is the regulator that you are using? I think that the mixing between 3.3v and 5v transceivers is not the problem, because https://e2e.ti.com/support/interface/f/138/t/230101?3-3V-Can-transceiver-and-5V-Can-transceiver-on-the-same-CAN-BUS and because the system worked using the evalution board power supply. Sent: Thursday, September 27, 2018 at 8:51 AM From: FLJ <[email protected]> To: [email protected] Subject: Re: [CANLIST] My device stops receiving when powered from battery Regarding the battery, it can definitely supply enough power to all 4 CAN nodes (this includes my device), because the working system is built to drive an electric motor as well. The battery could power the 4 nodes for hours if not days, since we are not powering the motor until the issue with the CAN is figured out. We are not adding any additional consumers. My device is a CAN logger, there is wiring in the system (CAN connector) for this purpose. We are provided only with CAN-H and CAN-L. For my understanding a common ground is ensured, since all nodes are powered by the same battery. On Thu, Sep 27, 2018 at 1:35 PM Christiano SA < [ mailto:[email protected] | [email protected] ] > wrote: At some point the battery would fail. It would not be normal to plug infinite nodes into the system without causing a side effect. Every battery has a max current. The external power worked because CAN Bus signal is differential (A-B) as well as RS-485 is also. I already saw in a book (Jan Axelson) saying that on RS-485 the common GND must be next to the signals. In OBD-II interface, I see that the GND goes along too. But I have already tested a RS-485 system without common GND and it worked, I do not know exactly how, it must have some protection mechanism that automatically balances the commons. > Sent: Thursday, September 27, 2018 at 7:09 AM > From: FLJ < [ mailto:[email protected] | [email protected] ] > > To: [ mailto:[email protected] | [email protected] ] > Subject: [CANLIST] My device stops receiving when powered from battery > > Hello everyone, > > as a software developer I'm completely perplexed by my current problem. I > only have basic HW knowledge and I mostly follow HW diagrams designed by > others. Until now I guess I was lucky. > > I have an embedded device built upon an STM32 F4 evaluation board and I'm > using a SN65HVD230 CAN tranceiver from texas instruments with it. > > I have a battery powered system consisting of 3 CAN nodes using NXP TJ1051 > tranceivers, I don't have much detail about the MCUs used. > > The system all alone communicates over CAN correctly as expected. > > If I connect my device to the system's bus, while I power my device from an > external power supply, everything works fine. I receive all the CAN > messages I want to from the systems nodes. > My device is configured in silent mode, I don't want to send anything. > > As soon as I power my device from the same battery as the system, I stop > receiving CAN messages. My device itself is working when powered from the > common battery, meaning I can connect with the debugger to it, set > breakpoints, etc.; only the CAN stops working. > > I've read a lot about common-mode voltage in the past few hours, and about > splitted termination, but I can't understand what the problem is. I > would've rather expected or understood if the device wasn't working when > powered externally, but everything on the same battery should've worked. > > Can anyone help me out please? > -- Archives and useful links: [ http://groups.yahoo.com/group/CANbus | http://groups.yahoo.com/group/CANbus ] Subscribe and unsubscribe at [ http://www.vector.com/canlist/ | www.vector.com/canlist/ ] Report any problems to < [ mailto:[email protected] | [email protected] ] > -- Archives and useful links: http://groups.yahoo.com/group/CANbus Subscribe and unsubscribe at www.vector.com/canlist/ Report any problems to --=_7018717f-78aa-43ee-9fb8-d0ca52af5081 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable <html><body><div style=3D"font-family: Verdana, Arial, Helvetica, sans-seri= f; font-size: 10pt; color: #000000"><div>This is when you start prodding th= ings with a scope.<br></div><div>The problem may be a combination of issues= in different devices. Seeing that it works with a separate battery (i.e. c= ompletely floating power), the "common" ground might not be that common aft= er all. <br data-mce-bogus=3D"1"></div><div><br data-mce-bogus=3D"1"></div>= <div>The quickest way to solve this is seeing what is actually happening on= the bus.<br data-mce-bogus=3D"1"></div><div><br data-mce-bogus=3D"1"></div= ><div>cheers,<br data-mce-bogus=3D"1"></div><div>Bram<br data-mce-bogus=3D"= 1"></div><div><br></div><hr id=3D"zwchr" data-marker=3D"__DIVIDER__"><div d= ata-marker=3D"__HEADERS__"><b>Van: </b>"Christiano SA" <christiano@engin= eer.com><br><b>Aan: </b>[email protected]<br><b>Verzonden: </= b>Donderdag 27 september 2018 15:09:47<br><b>Onderwerp: </b>Re: [CANLIST] M= y device stops receiving when powered from battery<br></div><br><div data-m= arker=3D"__QUOTED_TEXT__"><div style=3D"font-family: Verdana;font-size: 12.= 0px;"><div> <div>I am software oriented too, but perhaps you are using a regulator with= Max current different of the power supply of the evaluation board.</div> <div><span class=3D"short_text" id=3D"result_box"><span>That would explain = the different behavior. (There are a lot of people saying about 7805 regula= tor </span></span><span class=3D"short_text" id=3D"result_box" lang=3D"en">= <span>inefficiency</span></span><span class=3D"short_text"><span> when I've= googled)</span></span></div> <div><span class=3D"short_text"><span>Which is the regulator that you are u= sing?</span></span></div> <div> </div> <div>I think that the mixing between 3.3v and 5v transceivers is not the pr= oblem, because</div> <div>https://e2e.ti.com/support/interface/f/138/t/230101?3-3V-Can-transceiv= er-and-5V-Can-transceiver-on-the-same-CAN-BUS</div> <div> <div>and because the system worked using the evalution board power supply.<= /div> <div> </div> <div style=3D"margin: 10.0px 5.0px 5.0px 10.0px;padding: 10.0px 0 10.0px 10= .0px;border-left: 2.0px solid rgb(195,217,229);"> <div style=3D"margin: 0 0 10.0px 0;"><b>Sent:</b> Thursday, September = 27, 2018 at 8:51 AM<br> <b>From:</b> FLJ <[email protected]><br> <b>To:</b> [email protected]<br> <b>Subject:</b> Re: [CANLIST] My device stops receiving when powered f= rom battery</div> <div> <div>Regarding the battery, it can definitely supply enough power to all 4 = CAN nodes (this includes my device), because the working system is built to= drive an electric motor as well. The battery could power the 4 nodes for h= ours if not days, since we are not powering the motor until the issue with = the CAN is figured out. We are not adding any additional consumers. <div> </div> <div>My device is a CAN logger, there is wiring in the system (CAN connecto= r) for this purpose. We are provided only with CAN-H and CAN-L. For my unde= rstanding a common ground is ensured, since all nodes are powered by the sa= me battery.</div> <div> <div> </div> <div> </div> </div> </div> <div class=3D"gmail_quote"> <div>On Thu, Sep 27, 2018 at 1:35 PM Christiano SA <<a href=3D"mailto:ch= [email protected]" target=3D"_blank">[email protected]</a>> wr= ote:</div> <blockquote class=3D"gmail_quote" style=3D"margin: 0 0 0 0.8ex;border-left:= 1.0px rgb(204,204,204) solid;padding-left: 1.0ex;">At some point the batte= ry would fail.<br> It would not be normal to plug infinite nodes into the system without causi= ng a side effect. Every battery has a max current.<br> <br> The external power worked because CAN Bus signal is differential (A-B) as w= ell as RS-485 is also.<br> I already saw in a book (Jan Axelson) saying that on RS-485 the common GND = must be next to the signals. In OBD-II interface, I see that the GND goes a= long too.<br> But I have already tested a RS-485 system without common GND and it worked,= I do not know exactly how, it must have some protection mechanism that aut= omatically balances the commons.<br> <br> <br> > Sent: Thursday, September 27, 2018 at 7:09 AM<br> > From: FLJ <<a href=3D"mailto:[email protected]" target=3D"_blank">= [email protected]</a>><br> > To: <a href=3D"mailto:[email protected]" target=3D"_blank">canlist@c= anlist.org</a><br> > Subject: [CANLIST] My device stops receiving when powered from battery= <br> ><br> > Hello everyone,<br> ><br> > as a software developer I'm completely perplexed by my current problem= . I<br> > only have basic HW knowledge and I mostly follow HW diagrams designed = by<br> > others. Until now I guess I was lucky.<br> ><br> > I have an embedded device built upon an STM32 F4 evaluation board and = I'm<br> > using a SN65HVD230 CAN tranceiver from texas instruments with it.<br> ><br> > I have a battery powered system consisting of 3 CAN nodes using NXP TJ= 1051<br> > tranceivers, I don't have much detail about the MCUs used.<br> ><br> > The system all alone communicates over CAN correctly as expected.<br> ><br> > If I connect my device to the system's bus, while I power my device fr= om an<br> > external power supply, everything works fine. I receive all the CAN<br= > > messages I want to from the systems nodes.<br> > My device is configured in silent mode, I don't want to send anything.= <br> ><br> > As soon as I power my device from the same battery as the system, I st= op<br> > receiving CAN messages. My device itself is working when powered from = the<br> > common battery, meaning I can connect with the debugger to it, set<br> > breakpoints, etc.; only the CAN stops working.<br> ><br> > I've read a lot about common-mode voltage in the past few hours, and a= bout<br> > splitted termination, but I can't understand what the problem is. I<br= > > would've rather expected or understood if the device wasn't working wh= en<br> > powered externally, but everything on the same battery should've worke= d.<br> ><br> > Can anyone help me out please?<br> ><br> --<br> Archives and useful links: <a href=3D"http://groups.yahoo.com/group/CANbus"= target=3D"_blank">http://groups.yahoo.com/group/CANbus</a><br> Subscribe and unsubscribe at <a href=3D"http://www.vector.com/canlist/" tar= get=3D"_blank">www.vector.com/canlist/</a><br> Report any problems to <<a href=3D"mailto:canlist-owner@vector-informati= k.de" target=3D"_blank">[email protected]</a>></blockqu= ote> </div> </div> </div> </div> </div></div> -- Archives and useful links: http://groups.yahoo.com/group/CANbus Subscribe and unsubscribe at www.vector.com/canlist/ Report any problems to<br></div></div></body></html> --=_7018717f-78aa-43ee-9fb8-d0ca52af5081-- -- Archives and useful links: http://groups.yahoo.com/group/CANbus Subscribe and unsubscribe at www.vector.com/canlist/ Report any problems to <[email protected]>