what is the difference between different microcontrollers?

Hi all,

can any one tell me the difference between different microcontrollers (89c51/52, AVR, PIC, ARM/LPC) and their advantages and disadvantages one over the other? for what specific applications a microcontroller is preferred over the others?
i am asking as i am new to professional field and dont have lot of experience.

Regards

AVRs PICs and 8051 like devices are lower end.
They use 8 bit architecture. ARM on the other hand is 32 bit.

A wider bus allows you to interface with more memory and makes the transactions denser. an 8 bit device running at 50Mhz is actually slower than a 32bit device running at 20Mhz

Think of the bus as a highway - the more lanes it has, the more traffic can go through.

There're many other differences between the cores you listed - but the bus width is the most important thing to consider.

thank you shaiko. you really give me a nice information about data bus width and corrosponding speed. please also tell me about different applications where we can use one microcontroller effectively wile others are not. like pic and avrs have inbuilt adcs and 8051s have not etc.

PICs are NOT 8 bit. There are 8 bit, 16 bit and 32 bit versions.

Keith

the mcu is depending to the application.

for example
a tempeture meter you need only a small 8 -bit msu
for a dvd decoder you need a arm 32-bit mcu

please tell us what is your flied application and i will recommend you some mcu families.

Qaisar Azeemi,

I think you're a little cofused.
8051, PIC, ARM, SPARC, MIPS, etc...describe the logic CORE of the device (the CPU).
ADCs, PWMs, Timers, USB controllers, Ethernet are peripherials that surround the CORE.

A microcontroller is actually a SOC (system on chip). It has the CPU and other surrounding peripherials (such as an ADC) on the same chip.
For example, 2 devices that use an ARM cpu core can have very different peripherials...

Determining the exact device to use isn't a simple decision. You have to be very familiar with the end application and the requirements in order to make a wise decision.
There're many things to consider:
Power consumption, available peripherials, foot print, cost, memory...

---------- Post added at 12:48 ---------- Previous post was at 12:38 ----------

As a general rule, I'd use the simplest device that can do the job.
If you can controller your elevator using a simple 8 bit PIC, there's no reason to use a power hungry, expensive and large 32 bit dual core ARM with 4GB of external memory.
However, if you want to provide internet access and do facial recognition of the people that use your elevator, probably - a simple AVR will cut short.

thank you shaiko, you have given me to the point information. if i ask more specifically then i will ask like that.......

can every project be designed using only one microcontroller? like i am currently working on 89c51 ,,, so is it enough for all microcontroller based projects? irrespect of cost, power consumption , etc

Qaisar Azeemi said:

can every project be designed using only one microcontroller? like i am currently working on 89c51 ,,, so is it enough for all microcontroller based projects? irrespect of cost, power consumption , etc

Click to expand...

No single microcontroller is the best fit for all microcontroller based projects. For example the throughput or operational frequency can be a limiting factor in some applications.

All 8051 variants are not created equal as well. Some 8051 variants have a peak performance of 2MIPS while others have performance levels in the 150MIPS range, like some of the SiLabs 8051s.

Some applications require the processing of large amounts of 32-bit numerical values, in which case a 32-bit processor like ARM, PIC32 (which is actually a MIPS architecture) or AVR32 for example.

BigDog

okey,Not best one,suitable is best!

It is generally a good practice to develop your application using some device with large capabilities (fast, lots of ram, flash, peripherals etc) and then when desired functionality is achieved you can minimize the design to use something more cost effective. The advantage is that you know what too look for because you know exactly what you need for your design to function properly.

I'd generally say that simple tasks or high reliability tasks (like advanced watchdog for some complex circuit) are domain of 8-bit controllers while "crunching numbers" is a domain of 32-bit ones (mostly various flavors of ARM architecture with tiny addition of MIPS, SPARC, AVR32, ColdFire and alike).

I generally prefer to use 16-bit ones from Microchip and TI (but that's more because I got used to using them and I know them better than other families).

Of source there are cases when special parameters are required. For example there are microcontrollers from Infineon, Freescale and Toshiba which can operate up to 7-8V and withstand few seconds of 10V+. They don;t excel in neither operating speed or memory density, but are more robust against conditions which would kill any normal MCU (hello automotive )