Which communication is best between several microcontrollers.

[veerubiji]

Hi everyone,
I have assigned a project to find the best possible communication between several PCB boards which having microcontrollers for specific function. I need to communicate all microcontrollers with the main board which contains CPU. I need to send some information from mainboard to the controllers and receive response from the controllers. Each controller board is designed for specific purpose. I don't need to communicate between the microcontrollers but even if one microcontroller fails to communicate then it won't effect on others. Presently i need to communicate six microcontrollers but in future more than that. I want to avoid more wired connections between mainboard to other controllers(it should be less).

The communication won't effect by the temperature(100 to 120 degree) and pressure(high). The distance between mainboard to final controller may be more than 1 meter. Which type of controllers are best? I need to perform some calculations and sensor readings. Each board having more than two sensors. I need to perform some calculations on sensor readings or send values directly.

I am new to this type of project. I have searched for the best communication but i am confusing which is best. Some people suggesting me to use CAN Communication. If i choose CAN communication what type of microcontrollers is best? I have attached simple diagram how it gonna looks like as shown below. Please anyone suggest me.

 

[barry]

CAN sounds like it may be a little overkill for your application. Or maybe a LOT of overkill. I2C or SPI may be a better choice since they are significantly simpler. I'm not sure why temperature or pressure enter into this (and HOPEFULLY those temperatures are F, not C). You didn't specify data rate which is a KEY parameter; without that it's impossible to make an intelligent decision (but it SOUNDS like you have a pretty simple requirement).

 

[veerubiji]

The temperature range is 100 to 120 degree C. I am looking for communication which won't affect by temperature and pressure because I am designing a downhole electronics project, the equipment will go to bottom sea. I am thinking if i use SPI or I2C then it needs more wired connections from main board to other boards. I want to avoid more wired connections because of some problems for people working in offshore.Even i need high data rates because may be in feature i am able to connect some special equipment which need high data rate(in order or Mbps).

 

[Murugesh_89]

Hi,
The best way i recommend is RS 485 communication.

You will require only two wires A,B if you are going to use same power supply for all the boards. Unlike SPI,I2C, this protocol is highly reliable over long distance too even with the data rate of about 2 Mbps. I suspect SPI,I2C will create issues when you are placing your slave boards quite longer from master.

The other way to do is by using Wifi. But i dont know how effective it will be under sea. If it is above ground level this would be more easy as no wiring involved as you wanted. But it will be costlier.

Regards,
Murugesh

 

[veerubiji]

The distance between master and other microcontroller boards will be in meters(may be 2 to 5 meters). Yes it is best if i can use same power for all the boards. Can i connect all boards with only two wires from the main board? Can you suggest me some tutorial about RS485 communication.

 

[Murugesh_89]

I think it is much better to go through the MAX485 IC datasheet.
All the information is available there.
a. How to connect the A,B line with other units
b. How to use the half duplex mode

The only thing is that you need to terminate the last node by using a 120 ohms (impedance of used wire) resistor to avoid the data returning back.

 

[veerubiji]

Thank you very much for your suggestion. I will look into that.

 

[barry]

Yes, RS-485 (or RS-422) would be a good choice. What about fiberoptics?

 

[veerubiji]

I don't have any idea about how to use fiberoptics communication? If it is better than above RS-485 then i will proceed with that. Can you give me some articles or some tutorial that can understand fiberoptics.

 

[barry]

Here's a start (there's plenty of info out on the web):
https://en.wikipedia.org/wiki/Fiber-optic_communication
https://www.radio-electronics.com/i...bre-optics/communications-basics-tutorial.php