How do you decide whether an application may require a microcontroller or a processor?

I found that the selection of processor or microcontroller for an application, depends on the requirements of the application.

I am sure here will be many people who use both processor and microcontroller.

 

IMHO that is not likely to be the case. Increasing levels of integration allow a processor to be combined with the peripheral devices you need on a single chip. This level of integration is essential in reducing the overall cost of a project. I stopped doing processor designs in the mid 1980s.

 

Hola PB
What are the respective current definitions to use for comparing them?

 

I occasionally get nostalgic about having to use the 40pin Intersil IM6402 UART!

 

Hola PB
What are the respective current definitions to use for comparing them?

A processor has no peripheral devices or memory on the die with the CPU.
A microcontroller has all of its program, data, & non-volatile memory on the die along with a selection of peripheral interfaces used in various applications.

 

Thanks PB. Clear enough.

 

A processor has no peripheral devices or memory on the die with the CPU.
A microcontroller has all of it program, data, & non-volatile memory on the die along with a selection of peripheral interfaces used in various applications.

So, you would only use a processor if you can't find a microcontroller with enough memory.
[EDIT] Having said that, if you didn't need to read or write to the memory quickly, you could still use a microcontroller with I2C or SPI to write to external memory ICs, or even an SD card.