several arduino connected together

Forum 2005-2010 (read only) Hardware Interfacing
1

Hi,

I'm working on a Project where I got know into a problem.

I git seven independent Arduino with some buttons.
They are all connected together from one to the other with just 4 wires. (two for the Power two for RX TX)

Now when a Button has been pressed it should send a value to the main Arduino which will present the result on a PC.

How to transfer the Data over 7 Arduinos? I can't just take one wire and attach it to the RX the other one to the TX. It doesn't work..

Arduino 1 Arduino2 Arduino3 Arduino4 PC
RX------------RX-----------RX-----------RX-----------RX
TX------------TX-----------TX-----------TX------------TX
GND----------GND--------GND---------GND----------GND
5V------------5V-----------5V-----------5V------------5V

Does someone have an Idea?

Thx
Andy

2

  1. PC - flip RX/TX around; call this one "Master"

  2. Arduinos 1-n - add a diode to each TX output before connecting to the common "bus"; this is to prevent a TX signal from one Arduino slave from backdriving/interfering with other slaves.

Now write the software where the master PC addresses the slave nodes 1-n in a round robin fashion, and waits for data from each. Obviously there's more to this, but what you're basically fashioning is a serial bus.

3

thx a lot for the answers.
Thx for the tip with the Diode now it does work.

Each Arduino got its own address so the master can send individual message to it.

thx
Andy