Need Help for Home Automation

[localcrack]

I am doing home automation project

in that more then 32 nodes are connected to one master ciruit
all nodes requires to send data simultaneously to master.

I am using CCS PCW compiler by using microchip 18F series chip.

currently I not completed my hardware design

we need some hardware design and which protocol suitable for my design.
 

[oldvan]

CAN bus offers efficient way to move data around such a network.

[localcrack]

hello oldvan

In my home automation project I want to use twisted pair for sending data.
so I prefer 485 network

whether CAN works with 485 ?

whether I need special chip for CAN ?

[glenndr_15]

greetings!
I suggest the PIC18F452

best regards,

[cipiloi]

Hi localcrack !  look hier  http://www.abcelectronique.com/bigonoff/domocan.php?par=5e6d1  is very intersting!

[localcrack]

hello cipiloi

I can't find any things regarding my project

are you posted wrong link...? or I am wrong...?

[cipiloi]

Sory!  hier is domocan (home automation project)   http://www.abcelectronique.com/bigonoff/domocan.php?par=93b59     Is ok for you?

[leptro]

hello,
the link from cipiloi is good but is in french.
here is the direct link to the can page.


http://www.abcelectronique.com/bigonoff/domocan.php?par=30456

[localcrack]

anybody uses multi master over RS485

is it possible ?

[hate]

rs485 uses 1 twisted pair so multi master is possible but u have to check for collision!

Regards...

[localcrack]

hello hate

how can I detect collision on RS485

do you have any sample code ?

[hate]

No code but a quick idea maybe checking the line for changes for a certain period of time according to your baud rate. I mean checking the logical state not waiting for some data to arrive. If some transmission is going on, the logical state of the line should change with certain periods according to the baud rate so a second master won't start transmitting when the line is busy. Of course I'm assuming you're using transceiver chips like max485 vs. not some all-in-one 'transceiver encoder decoder' chip. Just an idea, don't know it'll work or not!

Regards...

[oldvan]

CAN is nothing to do with RS485, is a different protocol, different signal levels, etc.  Uses twisted pair wire.  Is quite commonly used in automobiles.

CAN has built-in collision detection, automatic retry, prioritized send, etc.  Is well-suited to a home automation project.

Perhaps you dismissed CAN a bit too soon in favor of RS485?  CAN be worth another look.  Visit Microchip website and it is easy to find a PIC18... or DSPIC... with 1 or more CAN transcievers built in.

[localcrack]

which one is the batter among this all

1) Modbus
2) simple RS-485
3) CAN bus
4) DMX512

[cipiloi]

CAN is perfect!

[blacknight72]

I also vote for CAN (Controller Area Network), it is well-known with its stability and error controlling, used popularly in cars and industry.

I've used CAN for my friend's Smart Home (just help him a little). It's very convenient for you to establish a system that manage all devices in a house.

When a node deliver a message to CAN bus, all other nodes, specified nodes or just one node can receive this message (we can do this by set filter & mask for each node, especially, we can change mask and filter at real time)

The maximum speed of CAN bus is 1Mbit/s

If you prefer Microchip's products, you can use PIC 18F4685-CAN intergrated or some devices in dsPIC33F & 24H family (ex: dsPICJ128GP706, dsPIC33FJ128GP710 ... you can use Microchip MAPS http://www.microchip.com/maps for choose an appropriate device) that support ECAN. In addition, you will need a CAN transceiver (MCP2551).
I've used dsPIC33Fj128GP706 for this application. It is okay . I also recommend using PIC 16bit family with ECAN (Enhanced CAN) will be better than CAN.

Good luck with you project

[adrian]

I second on that, Very reliable. I've used 18F2680. I've even send power true cat5 to my nodes. Eg. Cat5E- 3for power, 3 for ground, and 2 for CAN-H and CAN-L. No package lost or watsoever.
With 1 condition- Calculate ur current need.
Only meant as monitoring nodes (power for mcu).
Imagine 20*50mA = 1A :p  
Use separate power source if need more current. Then only need 2 for CAN-H and CAN-L.
best wishes and Good luck.

ps: Please thanks us by clicking on "Thank You" if u find it useful/ contributed to any new ideas.

[janakfun]

Well if you have time to undersatnd the CAN protocol then go for it. It is best suited for your project.
Modbus is  simpler one but I dont prefer it for time critical applications.
Microchip already has controllers with in built CAN facility. and you can find the source code for that too.
But undersating the code will be a bit headache for you..
Anyway All the best..

[orange]

I suggest this one.

http://www.hth.com/snap/

[king]

From my point of view Can is Best but if you want to complete your project in simple,easy and cheaper way then go for RS422 you just have to use SN75176A based circuitry to design the hardware for taking data from 32 different slaves devices to one master.Make your circuit in Full duplex mode for this you have to Use Two Sn75176A (RS422 Driver IC) in each master and slave circuit one for the TX and one for the RX.

[Ichan]

As the topic is about Home Automation then i think X10 is the most used widely, it is a power-line communication protocol. A lot of information on the net, and the wikipedia is a good start http://en.wikipedia.org/wiki/X10_%28industry_standard%29.

-ichan

[MGLSOFT]

I prefer to use CAN, besides the characteristics mentioned by other users, has an additional advantage over other systems.
It incorporates the ability for any node send messages without anyone's request, this can happen because a variable to measure change in value or because they are programmed to send messages every xx time.
That makes it very powerful, as it lowers the rate of communications in great shape.