[VicPiMakers Projects] Can-bus like apartment project

[Craig Miller]

George,

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.

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).

Craig...
-- 
IPv6 is the future!
http://ipv6hawaii.org/


On Sun, Oct 25, 2020 at 11:13 PM James Briante <briantej at gmail.com> wrote:

> George,
> 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.
>
> Below is a link on a network using 1-wire for home automation.
>
>
> https://www.instructables.com/Home-automation-project-based-on-1-wire-devices/
>
> On Sun, Oct 25, 2020 at 11:13 AM George Bowden <gtbowdeng at gmail.com>
> wrote:
>
>> Hi all
>> How to ground devices on a DIY low speed fault tolerant Can Bus??
>>
>> 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.
>>
>> 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..
>>
>> I'm using the fault tolerant low speed can bus standard.
>> <https://en.wikipedia.org/wiki/CAN_bus#/media/File:ISO11898-3_Waveform.svg>
>> 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.
>>
>> [image: image.png]
>>
>>
>> --
>> George Bowden, vice president, Victoria Computer Club
>> gtbowdeng at gmail.com
>> --
>> Projects mailing list
>> Projects at vicpimakers.ca
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>>
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