Jantje:
Chagrin:
A microcontroller like an Arduino is your interface to the sensors/motors/etc. On a large project you should think of it as a peripheral device which should be controlled by a microprocessor-based system like a Raspberry Pi.Is this a commonly accepted rule?
Depends on the complexity. But maybe I am not common. The usual rule in industry is to buy what you need and minimize the number of devices as possible/practical. Micro-controllers and Microprocessors are basically the same thing. The first just has useful peripherals to interact with the real world in real time that the second doesn't, but usually gives up stuff like processing power or advanced math functions. There is a different complexity to networking multiple devices together for communication. Also, using a single device is required for real-time applications (say motor controllers). Millisecond latency that is standard to most PC OS's (which the Raspberry pi uses) is not acceptable if you are trying to control a CNC mill. That being said, you can get real-time processing on the Raspberry Pi, it is just more complicated.