How many Sketches can be loaded onto Uno

I'm a total newbie.

How many Sketches can be loaded onto an UNO at one time? Is it only 1?

My build includes a LCD Monitor, RTC, Temp Sensor, Timer (for lights), & a Stepper Motor Controller.

Do I write "Modules"/Sketches for each component and then refer to that sketch in the Master Sketch, or do it all within the Master sketch?


A sketch is the Arduino term for project, it can have many files ( .ino, .cpp, .h ). You cannot load multiple whole sketches, however you can combine the functionality into one large sketch.

Each module/component could be implemented in a .h/.cpp combo, you can also write re-usable libraries to extend your projects/sketches.

1 sketch - it will likely have multiple parts, with each part sequentially performing an action; or, performing an action at timed intervals - see Blink Without Delay.

For example, you may take update the time once a minute, and display it on the LCD; check the temperature every 30 seconds and display it on the LCD; turn the lights on or off every 6 hours; and be doing something with a stepper motor almost continuously anytime that one of the others is not occurring.

Thanks for the input. I'm really looking forward to playing around with the Arduino.