<div dir="ltr">George,<div><br></div><div>30 years ago, I created a radio station automation which used a RS-422 bus. The key was to use a bus that was balanced (read: no ground, but just + and -). By using balanced connection, it is easy to eliminate noise that might be induced into the wires, as they travel near items like fluorescent lighting or other noisey devices. Also when using a balanced bus, you don't have to worry about each of the devices using a different ground. </div><div><br></div><div>I don't know enough about the Can Bus or Dallas 1-wire, but I would definitely look for a bus that uses balanced signalling rather than a unbalanced (e.g. data and ground).</div><div><br></div><div>Craig...<br clear="all"><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div>-- </div><div>IPv6 is the future!</div><div><a href="http://ipv6hawaii.org/" target="_blank">http://ipv6hawaii.org/</a><br></div></div></div></div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sun, Oct 25, 2020 at 11:13 PM James Briante <<a href="mailto:briantej@gmail.com">briantej@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div dir="ltr"><div class="gmail_default" style="font-size:small">George,</div><div class="gmail_default" style="font-size:small">Re: grounding 2- twisted pair. The only communication that works on two physical wires that I'm aware of is the Dallas 1-wire and the CAN bus used in cars and industrial applications. In both cases there is nothing to ground. The CAN bus is available in PSoc 5 microcontroller from Cypress Semiconductors. Like all networks it requires additional hardware and a lot of spare time! Good luck on your project.</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">Below is a link on a network using 1-wire for home automation.</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default"><a href="https://www.instructables.com/Home-automation-project-based-on-1-wire-devices/" target="_blank">https://www.instructables.com/Home-automation-project-based-on-1-wire-devices/</a><br></div></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sun, Oct 25, 2020 at 11:13 AM George Bowden <<a href="mailto:gtbowdeng@gmail.com" target="_blank">gtbowdeng@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr">Hi all<div>How to ground devices on a DIY low speed fault tolerant Can Bus??</div><div><br></div><div>
I'm planning about a dozen sensors
in several rooms in my apartment
, a couple actuators, a few micro controllers and a Raspberry PI communications hub that connected to the internet for sending SMS messages to my phone .
STM32 microcontrollers don't normally come with wifi so a wired network of these cheap devices in an apartment is reasonable. </div><div><br></div><div>I've chosen a single unshielded twisted pair Can Bus, tacked in the ceiling corners where it is almost invisible. Yes, I thought about doing it other ways and chose this. The antenna aspects might be challenging.. </div><div><br></div><div>I'm using the <a href="https://en.wikipedia.org/wiki/CAN_bus#/media/File:ISO11898-3_Waveform.svg" target="_blank">fault tolerant low speed can bus standard.</a> The bus will be optically isolated from the balcony. Can I use ground from AC power as a common ground between devices? I think ground loops in this environment will be negligible. </div><div> </div><div><div><img src="cid:ii_kgpe96b70" alt="image.png" width="471" height="425"><br></div></div><div><br clear="all"><div><br></div>-- <br><div dir="ltr"><div dir="ltr"><div>George Bowden, vice president, Victoria Computer Club<br><a href="mailto:gtbowdeng@gmail.com" target="_blank">gtbowdeng@gmail.com</a></div></div></div></div></div>
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