Arduino UNO and DUE project feasibility

Hello everyone.

I have a basic question about Arduino UNO and DUE, just double checking with you to make sure I am understanding correctly.

What I need for my project is an Arduino which can receive and send ethernet commands to some ports, and send/receive Serial RS232 commands as well. Also, to handle GPIO.

Could you possibly tell me if the following sentences are correct:

Arduino UNO - I can install the Ethernet Shield and the Serial RS232 shield on top of each other. - Installing those two shields implies that I am going to lose some of the GPIO, which are used by the shields. But I can still use the other GPIOs.

Arduino DUE - Ethernet and Serial (RS232) shields are compatible with Arduino DUE. Actually if I am not mistaken Arduino DUE comes with RS232, so I won't need the SERIAL shield. - All the leftover GPIOs will still be available when the Ethernet shield (and eventually the Serial one) are in place.

I saw on the market and Arduino UNO with ethernet on it. Is that an official Arduino board?

Thanks for your help!


by rs232 do mean +12v -12v for communicating with a pc (or mac) comm port or 0-5v for communicting between processors? if 0-5v the Arduinos both have a built in uart so no shield is necessary. I don’t know anything about the ehernet shield.


I need to communicate with external devices, RS232 capable. Is the RS232 built in the DUE suitable for communicating with external devices?

Thanks for your help! Tony

I don't know for sure about the Due but I doubt it. You will probably need the level shifters (look up MAX232 or 233) to communicate with a pc type comm port. The Max233 is easier to use as it doesn't need caps for its charge pump (5v to -12 and +12 volt converter).

Not a problem, I just need to know, thanks.

I read that the MEGA is a 5V device, it may be a more suitable board for the ethernet shield, which is a 5V shield?

RS232 built in the DUE

No Arduinos have RS-232 built in, they all have 5v or 3v3 serial.

If you have to interface with a genuine RS-232 device you need level converters as mentioned above. In which case you need a shield so as long as the shield is suitable for it's host board it doesn't matter if you use a Due, Mega or a Uno.


Also look into the software serial library. You can set up a second serial port to communicate with external devices and use the hardware serial (pins 1 and 2 on the UNO) for programming and debugging.

Thanks guys.

I think things are getting clear.

Just another question, I fail to clearly understand the difference between the MEGA and the DUE. Is it only processor power? Since the MEGA is 5V I was thinking that maybe it's a better choice for me. All the Arduino Shields working for 5V would work with the MEGA as well, is that correct?

Thanks Tony

The mains diffs are processing power and operating voltage.

All the Arduino Shields working for 5V would work with the MEGA as well, is that correct?

The Mega is 5v so it should be correct.



I think I would like to try a DUE, but still I cannot find online an answer to a very basic question: are the official shields from Arduino compatible with the DUE? In particular, is the ethernet shield compatible? I read about a feature that allows the shield to auto-regulate the voltage, but there is no mention of DUE compatibility on the ethernet shield page.

Cheers for your help

Anybody? Thanks!

I did look at this once before and IIRC the Ethernet part should work, but the SD card won't because it drops the expected 5v down to 3v3 just usign a voltage divider so if that starts with 3v3 it will drop even further to something like 2v1 and I doubt an SD card will work at that voltage.

Don't get the shield based on my memory though.

I've not looked but if this sort of information is not on the official pages it should be, it's pretty basic and for official shields at least people should be able to buy with certainty that something will work.