3 way communication

Is there a way for 3 arduinos to communicate together, but without having to use a huge bus. I thought that I2C or the SPI interface might work, but I was wondering if you had any ideas.

popa

Both I2C and SPI can have multiple devices. I believe SPI is the more reliable.

Another option might be NRF24 wireless transceivers.

...R

WiFi

Mark

wifi is a idea but I don't want to buy tons of shields, because at least I will have to buy seven shields.

Is there a way for 3 arduinos to communicate together, but without having to use a huge bus

You might could use the arduino serial ports if you put a diode on the arduino tx pins.

popa6200:
wifi is a idea but I don’t want to buy tons of shields, because at least I will have to buy seven shields.

You can do WiFi with the cheap ESP8266 devices. However I think the NRF24 transceivers would be even easier as no “web code” is required.

Tell us what you actually want to achieve and you will get much better advice.

…R

How far away from each other are these Arduinos?

The little nRF24L01+ modules are about $2 each but it's hard to beat wire for easy.

RS485 can be used with multiple controllers but you need chips to convert the TTL signal to the balanced RS485.

RS485 is probably the "norm" for controller to controller communication. Modbus systems often uses RS485.

nRF24L01+ modules require more code overhead and are subject to interference from wireless keyboards and Bluetooth devices. Also nRF24L01+ can be blocked by people being between the transceivers. (I think. I can never replicate this when I try but ever now and then my transceivers sure have a hard time talking to each other.)

If the Arduinos are close together, you could probably get by with just using direct wire connections. You could either use asynchronous serial (TTL) or I2C.