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Selecting Your First Microcontroller

Selecting your first micro controller as a newbie is really difficult as most ofus have no idea which offers what , how difficult it'll be to program and othersuch things .Here is a little guide to help you out and get started with

selecting your first uC . Here 8 bit varieties of the uC's are taken and arecompared in an broad overview and not sticking to a single uC for the 3series.

From a new bies point of view here are a few things that he is usuallyconcerned with

- Availability : The availability is a major issue here in India as most uC areavailable in metros only . The availability scenario is something like this x51> PIC > AVR . x51 series has been around for about 20 years and now isavailable through many vendors and lots of flavors , but generally used are

the 2051 , 89s52 and 89s8252 . So go for x51 if you can find any others .PIC is also relatively easy to find and the most often used is the16f87x[x=3/4/6/7],16F628 and 16f84 . The avr is also easily available butonly in metros and other major cities common ones are mega8 , at90s2313 ,8515 , mega16 , mega 128 .

- Cost : uC is not a piece of silicon which you buy every day , decent oneswill burn a hole in your pocket . So making the right choice can save you alot of money. The scenario is something like AVR == PIC > x51 with mostseries of avr having a pic counterpart with similar price . but if you reallywant to save money the x51 will come at half the price of the starter chip byany of the other two series . x51 start around Rs 60 for 89c51 ( 4kprogrammable flash ) . With the AVR and PIC with there at90s2313 and16f84 starting around Rs 130 and RS 135[16F84/16F628] respectively .

- Programming the uC : The programmability is one of the most importantfeatures . If you are not able to build/buy/find a programmer for you uC thenthe uC is of no use . Here is what i have seen AVR < PIC < x51 so you seethe avr series is the easiest to get up and running with the minimum effort ,next is pic then x51 . Also remember most avr series support ISP ( InSystem Programmable ) feature which allows you to program the uC withouttaking it out of the circuit saving lots of time and helps not breaking you uClegs . PIC has multiple voltages for programming so you can easily end up

screwing your computer ports . The 16F87X series, 16F627/28/48 supportsICSP.Programmers available within 500 Rs price range. x51 though high endones support ISP starters require a big circuit with various voltages ( unlessyou have a programmer around dont waste time building one ) .

- Price / Features ratio : We can not compare features without price becauseall series have all the features you want in the various offering ( PWM ,multiple UARTS , USB , ISP what not .. ) So we will take which offers what at

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what price . SO i found it something like this AVR > PIC > x51 . Here alsoAVR is the winner ATMEGA8 for examples has most of the features one wouldwant with a price of around < Rs 200 . x51 low end series are quite plain inthe extra features offered while PIC is a little expensive compared to AVR forsame features .The 16F87X series, 16F627/28/48 has hardwarePWMs,onboard clock,UART,comparators,multiple ADC,supports ICSP.USBsupport available on certain PICs.

- Performance : Sometime your application needs to literally be fast andfurious and you need speeds in Mips[Million Instructions per second] . In thisthe choice for you is AVR its a RISC architecture with 16 Mhz uC capable ofclocking a cool 16 MIps . So its like AVR > PIC > x51 . x51 is slowest of thethree and PIC usally takes 4 cycles for a instruction[hence a 4mhz PIC willrun at 1MIPS] . Such power is required in applications where you need lots ofspeed ( USB , Web servers etc ) .

- Hobby support and circuits : This is how much help and support is available

for the various series of the uC . How many people have made there projectsonline . Its like x51 > pic > avr with x51 being the grand daddy being themost used and lots of projects have been done using it . PIC comes in seconddue to its wide availability and price/features while avr being relatively newdoes have a lot of help which is properly organized .

- Open Source Tools available : If you can get a decent compiler orassembler for your uC then youll be wasting time due to the un-optimizeddevelopment environment . Here is what i think AVR > x51 > PIC . AVR hassome very good tools available for free with support for amny languageswhile x51 comes in second ( It has much more tools than avr but they are

not free ) and last is PIC .The PIC has C compilers like HITEC C, CCS andbasic like PIC BASIC Complier,PIC BASIC PRO(picbasic.com)

- Learning curve : The learning curve is how easy is it to learn a uC it goessomething like AVR < PIC < x51 with AVR being the easiest to learn and PICcoming in second due to its a little cryptic instruction set . Also if u got agood easy to use programming language like c,basic with inbuilt libraries[rather than assembly],u got a ramp curve] and x51 coming last with its notso easy instruction set and usage . Please remember if you plan to read frombooks then the amount of written content in India for various uC is the exactopposite with ost for x51 and least for avr .

So here is what i recommend

You need lots of features with high performance at decent price : AVR

Availability is not much of an issue[Mumbai and Blore have dealers for allpics]and features required[offers ADC,USART,PWM,Comparators] but nothigh performance[agreed] : PIC

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You have a price limit and want to perform limited things : x51

I hope this was helpful in selecting you first uC please post in the forums ifyou still have doubts .