µC and µP

Often i have been asked to by people what is a microcontroller (µC) and how it is different from a microprocessor. In this post i will try to put some facts and let the reader decide how he would like to distinguish between the two.

For starters, both the µC and the µP are computational machines which are capable of doing complicated computations. The fuzzy word here is complicated, because what is complicated in one scenario might not be valid for other.

E.g. Then AMD processor on my home computer has to do a lot of computations when i do video conversion operations or run some matlab simulations. This however can be handled fairly well with the AMD. Trying to do this with a 486  is a foolsish proposition.

So what are the differences ?

• A µP contains more features which are meant for providing very high number crunching capablility and the peripheral units inside the µP are aimed at providing high speed data access and interfacing with other "ON board" chips.
• A µC contains a core ( for computational purposes) and peripheral units which are meant to provide a lot of I/O capablilites. These include Analog to digital converters, Ports for PWM generation, Ports for discrete outputs and Inputs etc.
• µC's generally contain a lot of on chip RAM, EEPROM and FLASH. FLASH and EEPROM are generally not found on a µC. However, µC's contain things like Barrel shifters, MMU's and typically a lot of cache memory.
• Talking about sheer computational speeds again the µC and µP have different set of speeds based on the application's for which they are targetted. There are µP's that run at 8MHz and those which run at more than 250MHz.
  
• Based on their intended application µP and µC's have a lot of communication interfaces ( CAN, SPI etc are common for automotive micro's, while USB is common in micro's for consumer electronics. Ethernet is almost a must for all networking microcontrollers).

Also one thing which you might not hear so often is the term "Reflashing" when it comes to µP's. This is because most of the µP's load run their software from the cache memory, which in turn is loaded from RAM ( usually DDR RAM in case of PC's. Now you know why more RAM equates to a better PC).

µP or µC both have very similar underlying concepts. It is only the usage and the cost that really drives what we use to solve a given problem.

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