Re: My device stops receiving when powered from battery
"Christiano SA" <[email protected]> Thu, 27 Sep 2018 15:09:47 +0200
| Newsgroups | gmane.comp.hardware.bus.can |
|---|---|
| Message-ID | <trinity-aaa3a2c6-1ec0-422e-9a85-31ae95192be9-1538053787454@3c-app-mailcom-lxa09> |
<html><head></head><body><div style="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="short_text" id="result_box"><span>That would explain the different behavior. (There are a lot of people saying about 7805 regulator </span></span><span class="short_text" id="result_box" lang="en"><span>inefficiency</span></span><span class="short_text"><span> when I've googled)</span></span></div> <div><span class="short_text"><span>Which is the regulator that you are using?</span></span></div> <div> </div> <div>I think that the mixing between 3.3v and 5v transceivers is not the problem, because</div> <div>https://e2e.ti.com/support/interface/f/138/t/230101?3-3V-Can-transceiver-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="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="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 from 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 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. <div> </div> <div>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.</div> <div> <div> </div> <div> </div> </div> </div> <div class="gmail_quote"> <div>On Thu, Sep 27, 2018 at 1:35 PM Christiano SA <<a href="mailto:[email protected]" onclick="parent.window.location.href='mailto:[email protected]'; return false;" target="_blank">[email protected]</a>> wrote:</div> <blockquote class="gmail_quote" style="margin: 0 0 0 0.8ex;border-left: 1.0px rgb(204,204,204) solid;padding-left: 1.0ex;">At some point the battery would fail.<br/> It would not be normal to plug infinite nodes into the system without causing a side effect. Every battery has a max current.<br/> <br/> The external power worked because CAN Bus signal is differential (A-B) as well 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 along 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 automatically balances the commons.<br/> <br/> <br/> > Sent: Thursday, September 27, 2018 at 7:09 AM<br/> > From: FLJ <<a href="mailto:[email protected]" onclick="parent.window.location.href='mailto:[email protected]'; return false;" target="_blank">[email protected]</a>><br/> > To: <a href="mailto:[email protected]" onclick="parent.window.location.href='mailto:[email protected]'; return false;" target="_blank">[email protected]</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 TJ1051<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 from 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 stop<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 about<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 when<br/> > powered externally, but everything on the same battery should've worked.<br/> ><br/> > Can anyone help me out please?<br/> ><br/> --<br/> Archives and useful links: <a href="http://groups.yahoo.com/group/CANbus" target="_blank">http://groups.yahoo.com/group/CANbus</a><br/> Subscribe and unsubscribe at <a href="http://www.vector.com/canlist/" target="_blank">www.vector.com/canlist/</a><br/> Report any problems to <<a href="mailto:[email protected]" onclick="parent.window.location.href='mailto:[email protected]'; return false;" target="_blank">[email protected]</a>></blockquote> </div> </div> </div> </div> </div></div></body></html> -- Archives and useful links: http://groups.yahoo.com/group/CANbus Subscribe and unsubscribe at www.vector.com/canlist/ Report any problems to <[email protected]>