Raspberry Pi Forums

Hello. I'm a student of electrical enginering and i'm trying to build my own simple microcontroller. I should have 22 GPIO pins and should be powerd and communicate over POE with Raspberry Pi who runs a MODBUS TCP/IP server. I'm fairly new to electronics
so i don't really know how to approach the problem. I don't want to complicate things and start from beginning and would like to know what what kind of simillar solutions were already done? The biggest problem seems to be POE. I found perfarduino whitch seems
to be a simple solution but i really have no clue how to set up POE. And thoughts?
Would be really grateful for any kind of help.

Check online for "PoE injectors" or "PoE splitters".


ghans

Do you really need the TCP/IP mode ?

Using the modbus serial RTU is way cheaper!

This is my post and you could change the cpu to get more I/O.

http://www.raspberrypi.org/forums/viewt ... 12#p538112

If you want to stick with the TCP/IP mode , you could use an arduino with a ethernet shield or with the WIZ550io Ethernet module.

The price will be around the same than a RPi but it will take less power and it will be more robust.

Or use a mbed NXP LPC1768.

Daniel

I realy need TCP/IP because it's the goal of our project. The requirements are: The size sould be less than 60x40x12 mm, 24 I/O, and should be powered over ethernet and communicate with modbus TCP/IP. Something like that: https://www.pjrc.com/teensy/ plus the POE.

There are plenty of Ethernet chips and modules that handle to TCP/IP stack for you.

http://www.microchip.com/wwwproducts/De ... e=en022889

Micro and Ethernet all in one chip

http://www.microchip.com/wwwproducts/De ... e=en026439

Yes there is a lot of ethernet chip!

But to start use a small cpu board, Arduino or Fubarino from chipkit with the I.C. you want for ethernet. This will speed up the process a lot since most of the libraries are there. Unless you are very good with one type of cpu.

I do have ethernet shields for the Arduino ( 2 types). One is very good and the other one ;--/ . I don't remember which one was better.

Once you have everything working , build your own board with all the I/O interface you need. Don't bother if it is a small quantity.


Daniel

It seems the objective is to develop a microcontroller board something like a Teensy, but with Ethernet and PoE.
The title suggests that using an off-the-shelf microcontroller board plus a "shield" is not "making my own".

Hi tadejkkk,

It is up to you !

Arduino or fubarino board from chipkit are good tool to progress. But you could use your own microcomputer.

I just gave you idea to speed up process because you had difficulty with the POE. And for me this mean that your electronic skill are maybe not enough to start from zero from microcomputer I.C. The atmega328 cpu is around $2 CAD so when everything is done it is simple to do your own board since you already test everything.

Daniel