communication b/w microcontrollers

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#1
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Hi

I want to communicate b/w 8 microcontrollers (long distance) ..

Each controller should transmit & recieve data ..

please help ..

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RS485 is great for long distance communication. You will have to devise a serial protocol of your own to use multi-master functionality, or have it master/slave driven (modbus RTU is an option for app level).

If you really want multi-master, you can use CAN with the appropriate micro.

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Since, you have just 1 post up, i'll assume that you need a simpler solution.
Long distance is always solved by wireless..
How long distance is this?
1> For few meters, use CC2500 Modules from TI.. They are SPI Based.. It supports one-on-one communication + brodcasting..
2> Develop a protocol using Zigbee.
3> Or just buy simple RF-Modules and start developing an advanced protocol..

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i don't need to use wireless module .. i want to use rs485 protocol .. & controller at89s51 .. can u show me some schematic .. how should i connect ..??

[cliff: if you are using at89s51 this is off-topic for AVR forum so I'll move it to General Electronics]

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What is modbus ?? how to configure that i need to config as single master multiple slave ..

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modbus is an internationally standardised protocol that is used to interface controllers like PLCs with other Devices..
Actually, RS485 can also be used for this purpose..

U didn't say what your distance was..
Are you thinking to run wires from one uC to another? What about voltage drop?
You might need to use Signal boosters between the lines..
In short, wireless might endup being the smarter choice..

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joy_shukla wrote:
.. i want to use rs485 protocol ..

Joy,

RS485 describes the hardware configuration. Modbus, SNAP and others describes the software protocol used over the RS485 setup.

If you google MAX485 you will find many examples of circuits designed to interface microcontrollers over RS485.

Cheers,

Ross

Ross McKenzie ValuSoft Melbourne Australia

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point A to point B, by wire: RS423 is commonly used, whereas others are multi-drop.

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I Googled but still don't know what a 'b/w microcontroller' is. Whazit?

Smiley

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smileymicros wrote:
I Googled but still don't know what a 'b/w microcontroller' is. Whazit?

Smiley

b/w => between

-Deven

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Joe,

Welcome to the death of the English language.

(considering that most mobile phones have a text prediction system such as T9 which actually spells words from a dictionary it's difficult to understand why people use txt spk?)

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f ts txt spk m ! ts ~ n ggle.

smly

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Well, I for one have no text prediction system, so I refuse to read shorthand :)

Even my cell phone has QWERTY. Even if it would not have, I would still not use text prediction system.

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smileymicros wrote:
f ts txt spk m ! ts ~ n ggle.

smly

Well it is now official Smiley ... you must be female because I don't understand a thing you are saying :lol:

Ross McKenzie ValuSoft Melbourne Australia

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valusoft wrote:
smileymicros wrote:
f ts txt spk m ! ts ~ n ggle.

smly

Well it is now official Smiley ... you must be female because I don't understand a thing you are saying :lol:
"If its text speak I'm surprised its not in google." I thought you dropped your vowels in text speak? I'm not sure if that's before or after you wipe the drool off your chin.

I Googled b/w before asking the question and didn't see it. I really thought is was some esoteric microcontroller.

But I guess I shouldn't get too uppity about this. I learned to touch type on an upright Underwood that you had to go slow on to prevent the character arms from locking up. I'm not sure there is a good reason to learn to touch type anymore. Times change.

Hey, do you remember that Star Trek movie when they went back into the past (our present) and Scotty spoke to a PC and Spock (IIRC) pointed at the keyboard and mouse so Scotty picked up the mouse and spoke into it? I laughed out loud on that one. Thats' what we need, computers with this icy distant echoing female voice accompanied by various meaningful dings and boops.

AND I admitted to being female in that pickup thread that's going on. Figured it would put folks off the troll chase, but I was wrong yet again.

AND just to keep this on topic, Joy... Modbus is a serial communication protocol and there are innumerable tutorials and at least one good AVR library that I can Google for you if you really want me too.

Smiley

Last Edited: Fri. Oct 16, 2009 - 12:56 AM
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That scene is in "Star Trek IV: The Voyage Home". Scotty ends up typing it in.

I think talking to computers as an interface is ridiculous. Try dictating a couple of pages of C. I'm sure typing it in is at least ten times faster and 100 times less frustrating :D

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jayjay1974 wrote:
That scene is in "Star Trek IV: The Voyage Home". Scotty ends up typing it in.

I think talking to computers as an interface is ridiculous. Try dictating a couple of pages of C. I'm sure typing it in is at least ten times faster and 100 times less frustrating :D

Years ago when the the Dragon text to speech thing came out, I got one and found that I could type stuff in much faster and more accurately than I could record and transcribe my voice. I bought it thinking I could dictate while commuting but due to ambient noise and my changing vocal tone while dodging in and out of traffic it was only getting about 3/4 of what I said.

Smiley