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Electronics => Electronics => Topic started by: geek1 on January 05, 2009, 03:20:30 PM

Title: Multiple microcontrollers
Post by: geek1 on January 05, 2009, 03:20:30 PM
Can someone give me a schematic for linking 2-3 ATmega8 microcontrollers together?






Thanks.
Title: Re: Multiple microcontrollers
Post by: Rebelgium on January 05, 2009, 05:48:30 PM
"linking them together" ? in what way? Use some rope, that'll go fastest.
Make it as easy as possible for us to help you, provide info.

you could let the two communicate via I²C. Google it. :)
Title: Re: Multiple microcontrollers
Post by: geek1 on January 05, 2009, 07:01:27 PM
Thanks, I tried googling I2C but couldn't find any schematics :'( Could you please give me a link?






Thanks.
Title: Re: Multiple microcontrollers
Post by: Ro-Bot-X on January 05, 2009, 07:39:39 PM
You may want to read this: http://www.societyofrobots.com/member_tutorials/node/35 (http://www.societyofrobots.com/member_tutorials/node/35)
Title: Re: Multiple microcontrollers
Post by: Rebelgium on January 06, 2009, 11:14:54 AM
Quote from: geek1 on January 05, 2009, 07:01:27 PM
Thanks, I tried googling I2C but couldn't find any schematics :'( Could you please give me a link?






Thanks.

I googled I2C schematic and found it immedeatly...
It's not much of a schematic anyway:
connect the two SDA pins to eachother, connect the two SCL pins together, and connect 2 resistors (2K2 if I remember correctly) to these two lines, and the other end of the resistor to Vcc. (pull up resistor)
Title: Re: Multiple microcontrollers
Post by: airman00 on January 06, 2009, 11:16:45 AM
Quote from: geek1 on January 05, 2009, 03:20:30 PM
Can someone give me a schematic for linking 2-3 ATmega8 microcontrollers together?
why do you want to link them? Many jobs can be done with one microcontroller .
Title: Re: Multiple microcontrollers
Post by: want2learn on January 06, 2009, 12:11:18 PM
I'm pretty interested in this thread too.
I'm still learning programming and can't wrap my head around the I2C software.
I've got a couple of ideas for multiple uC applications.
Any good links on I2C for people probably at a kids level of programming??
(no I'm not a kid but i figure if a kid can get it so can i)
Title: Re: Multiple microcontrollers
Post by: waymental on January 06, 2009, 12:35:17 PM
http://www.best-microcontroller-projects.com/i2c-tutorial.html (http://www.best-microcontroller-projects.com/i2c-tutorial.html)
Title: Re: Multiple microcontrollers
Post by: geek1 on January 06, 2009, 03:11:49 PM
Quote from: Rebelgium on January 06, 2009, 11:14:54 AM
Quote from: geek1 on January 05, 2009, 07:01:27 PM
Thanks, I tried googling I2C but couldn't find any schematics :'( Could you please give me a link?






Thanks.

I googled I2C schematic and found it immedeatly...
It's not much of a schematic anyway:
connect the two SDA pins to eachother, connect the two SCL pins together, and connect 2 resistors (2K2 if I remember correctly) to these two lines, and the other end of the resistor to Vcc. (pull up resistor)


Can you tell me which pins on the ATmega8 to do this with?







Thanks.
Title: Re: Multiple microcontrollers
Post by: Razor Concepts on January 06, 2009, 04:18:36 PM
http://www.atmel.com/dyn/resources/prod_documents/2486S.pdf
The top two pins on the top right of the MCU are SDA and SCL
Title: Re: Multiple microcontrollers
Post by: paulstreats on January 06, 2009, 05:24:34 PM
You must also understand that linking microcontrollers will only allow them to communicate with each other. They wont truly be able to share tasks or divide processing like this.

I remember a topic a while ago where I shared my ideas and pictures of my dual PIC board and there seemed to be a few people excited in the idea of having a dual processor board. But in reality all they can ever do is communicate with each other. (though by linking all of the pins you can create a supervisor / worker pair which is a project that i still want to investigate...)
Title: Re: Multiple microcontrollers
Post by: Ro-Bot-X on January 06, 2009, 05:56:06 PM
Quote from: geek1 on January 06, 2009, 03:11:49 PM
Can you tell me which pins on the ATmega8 to do this with?

Thanks.

Did you read all of the tutorial (I gave you the link in the previous post)? There is a schematic there... And if you take a look at the datasheet of the ATmega8 you'll see the pin configuration on the second page.
Title: Re: Multiple microcontrollers
Post by: TrickyNekro on January 06, 2009, 06:10:20 PM
It really depends on what you want to do...
I'm working on a UART chain for more that 2 microcontrollers, but really...
I need them for various tasks... One or more tasks per micro...
What you can really consider in programming is tasking...
Programming is for solving a problem with a certain sequence...
A problem is a task then... But a problem can also be divided to other smaller problems as tasks...
What I'm suggesting here is that knowing your task and hardware only leads you to correct results...

What is your application??? You may as well don't need two micros...
Title: Re: Multiple microcontrollers
Post by: geek1 on January 06, 2009, 07:51:44 PM
Quote from: paulstreats on January 06, 2009, 05:24:34 PM
You must also understand that linking microcontrollers will only allow them to communicate with each other. They wont truly be able to share tasks or divide processing like this.

I remember a topic a while ago where I shared my ideas and pictures of my dual PIC board and there seemed to be a few people excited in the idea of having a dual processor board. But in reality all they can ever do is communicate with each other. (though by linking all of the pins you can create a supervisor / worker pair which is a project that i still want to investigate...)




Can you tell me what the topic was called?







Thanks.
Title: Re: Multiple microcontrollers
Post by: Ro-Bot-X on January 06, 2009, 09:33:32 PM
Here is another nice into to I2C:

http://www.uchobby.com/index.php/2008/09/16/introduction-to-i2c/#comment-135985 (http://www.uchobby.com/index.php/2008/09/16/introduction-to-i2c/#comment-135985)