Can I connect two ARDUINO UNO circuit boards in serial to increase room for more code and more functionality. For instance I wish to connect six sensors to a board. I need code for all six sensors and there is not enough space on one board. If I connect two circuit boards in serial will that provide the space and functionality to run the code for all six sensors. If not how is this accomplished? I am a beginner with ARDUINO and I have been assigned a big task to make the ARDUINO UNO circuit boards provide six different functions using sensors such as temperature, pressure, humidity, voltage, current and possibly other functions. I am new at this.

  • You don't. Two Unos do not equal a Mega (or a cheaper ARM Cortex with a reasonable amount of resources). With some care you can probably fit everything you just described in the Uno's ATmega328p, but the ground rules of the assignment really need to be called into question, as unless there is closet full of hardware that is already paid for it is likely they were written by someone ill-informed. Jun 12 '15 at 5:21
  • It would probably be easier to optimize your code so that it fits. Reading six sensors doesn't sound too complex for an Uno. Jun 12 '15 at 9:26

There is no simple way to combine multiple boards into a unified system. What you will need to do is delegate certain tasks to each board and then have them communicate via SPI, I2C, or UART between a master board and each slave board in the system. The master system will then present the interface of the system as a whole via serial, wifi, console, etc.


If you're doing something that exceeds the resources of an UNO, then one simple next step would be to try a MEGA. It is similar enough to the UNO that porting should be trivial, but has more RAM, more flash, and more I/O ports than two UNO units combined.


What you described is not a big task. I suspect you are new to both the Arduino and computers in general, and so it seems big to you. Hang in there, it is a lot easier than you think.

In many cases, a sensor requires 1 electrical pin (plus ground, which is shared by all). So even an Arduino UNO can read a dozen or more sensors. In many cases the instructions to read the sensor is as simple as 'read(x)' and that takes 2 bytes, so if you got really lucky, the UNO's 32k of memory could read 16k sensors (a 'k' being a thousand if you didnt know).

Reality is it is not quite that simple, but it is not far from it. You probably want to find a library that matches your sensor, and the only hard part is figuring out how to combine many libraries, which indeed do interfere with each other on occasion.

Step 1, learn the basics. Get an Arduino experimenters kit or equivalent, play with the examples until you understand them. It will include some of the sensors you may use later.

Step 2, identify which other sensors you will need, find Arduino compatible versions of those. You will know if it is Arduino compatible if it has an accompanying library, get that also.

step 3, make sure you can make each sensor work by itself first.

step 4, start combining sensors and resolving errors that will show up.

Forget the idea of combining boards, it is an advanced topic and you are no where near ready to try that yet.

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