How to choose a Microcontroller?

This is very important question when starting this course. When you consult internet for this purpose, you will find a large number of dealers and manufacturers. which makes things complicated.There are a number design considerations that might immediately reduce your number of choices a great deal.

1- The first criteria for choosing a Microcontroler is "Number of Bits"; in market you will find 8-bit, 16-bit, 32-bit MCU(Micr-Controller Unit). Here we have to make our choice. Mostly for hobbiest and learners,the 8-bit MCU is enough. so eliminating other two will make our life much easy.

2- There are four "Major 8-bit MCU". They are, Motorolla's 6811, Intel's 8051, Zilog's Z8, and PIC 16X from microchip technology. Each of these MCU are different as their instruction set and registers are concerned, therefore they are not compatible with each other. Program written for one will not run on the other. We have to choose one from these four listed previously on the basis of the following criteria. Intel's 8051 based MCU are made by many manufacturers and are radily available in market. Among them are Intel itself, Atmel, Philips, AMD, Siemens, Matra, and Dallas semiconductors. Siemens and Intel are no more manufacturing MCU. The list of these companies along with their websites is given at the end.

3-Cost per Unit; for some people this might be unnecessary but i think for beginners and students this is most important. Why to spend too many dollars for making the same system when you can make it with a single dollar?. So, price consideration is very important. You can consult your local market for this purpose, but in Pakistan the cheapest MCU are from Atmel and PIC ranging form less than a dollar(Rs. 65) to few dollars(Rs. 350). Among these two companies PIC and Atmel, the MCU from Atmel are cheaper than that of PIC, and one thing more important you can also order a free sample of the MCU you wanted from the link given at the end.

4- Availibility in Market; so far we choose MCU from Atmel but we have to see which MCU are available in market now and in future. There are many varients in Atmel MCU like those listed in the following link;

http://www.atmel.com/dyn/products/devices.asp?family_id=604

So, you have to consult your local market that which microcontroller among these are available.
I picked Atmel's AT89C51, you can choose any MCU from AT8951 series. But do check the data sheet from the link given at the end of this post.

5-Package; Is the microcontroller which we need is a 40 pin DIP or QFP(Quad Flat Package)? so this is also considered. for most of the basic application we use only 40 pin DIP not the QFP.

6- Programing Language; This is also important for beginners to consider. Whether i know BASIC, C/C++ or Assembly. So, you have to also consider which MCU support the language you want. Atmel and PIC MCU support both C/C++ and Assembly.

Similarly Power Consumption, Number of I/O Pins, Amount of RAM/ROM Available on the MCU, Availibilty of Compilers, etc are also considered for choosing a MCU.


List of Companies Making 8051 Based MCU;

1- Intel; www.intel.com/embedded/index.htm
2- Atmel; www.atmel.com
3- Philips/Signetic; www.semiconductors.philips.com (OR) www.nxp.com
4- Siemens; www.eci.siemens.com
5- Dallas Semiconductors; www.dalsemi.com

Suppliers of 8051 based MCU from internet;
http://www.microcontroller.com/EmbeddedSystems.asp?c=11

Request Samples from Atmel;
http://www.atmel.com/forms/Samples.asp?family_id=604

Data Sheets;
http://www.atmel.com/dyn/products/datasheets.asp?family_id=604#770

If you like to study more on this topic you can go on these sites;

http://www.seattlerobotics.org/encoder/nov97/basics.html
http://www.egr.msu.edu/classes/ece482/Reports/appnotes/98spr/tsaimelv/appnote.html
http://www.tigoe.net/pcomp/code/all-about-microcontrollers
http://www.opencircuits.com/Microcontrollers