Maximum Serial Communications Distance (Length)

Projects Networking, Protocols, and Devices
1

Hi,

Is there a maximum distance that 2 Arduinos can communicate with each other using serial? 1 of the UNO's will already be an I2C slave to another I2C master so cannot use I2C.

I want to use a UNO to manage display of various types of data collected locally by the other.
I am limited as to the wires I have running from the data collector to the data displayer and thought I could use UNO's to overcome the problem. I cannot dig up the land and lay more cables but I need more sensor data displayed.

Thanks and kind regards,

jB 8)

2

Can you go wireless? There are numerous wireless modules that you communicate with via SPI for fast data transfers.

3

On the wired front

few feet using TTL
20M using RS-232
1200M using RS-485

Rob

4

I too vote for RS485 for wired connections. For wireless, I would use a ISM-band device with a good antenna.

For the OP, I doubt that I2C would work well beyond a few feet - I seem to remember that it was designed by Phillips for on-PCB use only.

5

I seem to remember that it was designed by Phillips for on-PCB use only.

That's correct, these days there are extenders but for 1:1 comms I2C has no benefit anyway.

Rob

6

But for some reason I have much better luck working with I2C devices than SPI ones. Must be me. That TI ADC I tried previously just made me cry uncle in the end.

7

Constantin:
But for some reason I have much better luck working with I2C devices than SPI ones. Must be me. That TI ADC I tried previously just made me cry uncle in the end.

I've worked some with both I2C and SPI devices and have come to the opinion that both buses are fully functional and useful. However the documentation supplied by many vendors chips make the task of getting them to work at first a lot harder then it should be, it's really a shame in some cases how bad and/or sparse the documentation can be from some device suppliers.

Once the specific protocol details for a given device are understood and applied I've found both types to work well. I believe SPI can be run faster then I2C if required. But I2C is easier and takes less hardware resources when one starts to or needs to add more and more devices to the bus.

Lefty