# how to identify the micro controller

Discussion in 'General Electronics Chat' started by vead, Feb 23, 2014.

Nov 24, 2011
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someone tell me that how we identify that micro controller is 8 bit or 16 bit

2. ### ErnieM AAC Fanatic!

Apr 24, 2011
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Best way: read the manufacturer's data sheet.

Nov 24, 2011
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i know we can do but can you tell me other options

4. ### spinnaker AAC Fanatic!

Oct 29, 2009
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Maybe you can tell us how you think someone will be able to tell you if it is 8 or 16bit?

If you expect an answer then you need to provide at least some information.

5. ### takao21203 Distinguished Member

Apr 28, 2012
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It's like saying "They make passage ways, and you can observe them crawling all over the place".

It is not a complete, sense making statement.

-Why would we want to identify if it is 8bit or 16bit?
-Where is this identification making process taking place?
-Is it a theoretical consideration, or dealing with some circuit containing a microcontroller?

Nov 24, 2011
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I am student I am planning to design 8 bit controller on computer but solid confused where to start I have little knowledge about controller
micro controller
cpu + memory
where cpu make with alu and control unit
cpu=alu + control unit
ALU =arithmetic + logic unit
logic unit= and gate , or gate , nand gate and so on...
and above all make with transistor and other.......

now I know how controller make but I don't have idea how to arrange the all part of controller example I know I want to make 8 bit controller but don't know following

1) how many bit are required to make CPU
2) how many bit are required to make ALU
3) how many bit are required to make decoder
I can read datasheet but I want idea how we can make specification for controller

I just want to hint how to decide bit for every part of controller ​

7. ### spinnaker AAC Fanatic!

Oct 29, 2009
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Number of bits are up to you the designer. You can have 2 bits, 4 bits, 8, 16. 32, 64.......

It will depend on your needs.

May 11, 2009
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9. ### takao21203 Distinguished Member

Apr 28, 2012
3,577
463
So it is a theoretical consideration.

It is mainly about the ALU when the number of bits is specified.

-The program counter normally will have more than 8bits (and also the address bus).

-For larger words, the ALU must use software (much slower).

If you mostly have 8bit data, lets say, you'd choose to use 8bit ALU.

If you often have 32bits data, you'd choose a 32bit ALU.

There have been 4bit controllers (they are somehow out of fashion these days). And also for instance 4bit RAMs.

Nov 24, 2011
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11. ### t06afre AAC Fanatic!

May 11, 2009
5,939
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Are you not a tad demanding now?

12. ### spinnaker AAC Fanatic!

Oct 29, 2009
4,866
988

What on earth are you talking about???? What specifications? How is anyone supposed to know what your requirements are if you can't define them?? Exactly what are you trying to do?

Jul 18, 2013
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The type and features of the μc is driven by the application, not the other way around.
Max.

14. ### spinnaker AAC Fanatic!

Oct 29, 2009
4,866
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Oh I see. It is related to this thread

Well people have done their very best to try and help you there. If you couldn't define your needs there, what makes you think a new thread is going to help?

I can understand the challenge of dealing with technology in a language that is not your first language. Sorry but this is an English language forum. Perhaps a friend can help you creating a post that will better define what you require?

15. ### takao21203 Distinguished Member

Apr 28, 2012
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Frankly I consider the hope OP can construct a microcontroller or create one in software is almost zero.

Among other things it requires to apply logic, grammar, and be able to use language on purpose and in a specific way.

Without a pun intended I dont think OP has reached that point, yet.

First make a webpage or blog and show your efforts and who you are, or nobody is going to build a microcontroller for you.

It is not just one evening posting on forums and get some specs or codes. It is weeks or months hard work.

Nov 24, 2011
621
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I want to design 8 bit micro controller on computer. first I need specification to design 8 bit micro controller. I have little knowledge about verilog language and FPGA I have done little work

micro controller (alu,control unit, decoder,counter,ram, rom , serial port, .etc)
CPU ( alu, control unit)
ALU (adder sub shift register )
CONTROL UNIT ( decoder counter )
MEMORY ( ram, ram)
serial port

all above define how micro controller construct

specification

micro controller 8 bit
CPU 8 bit
alu 8 bit
decoder ?
counter ?

don't know how to decide bit for decoder, counter

17. ### takao21203 Distinguished Member

Apr 28, 2012
3,577
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Then you can know how a moicro controller works.

For your info: A CPU is the same as a microcontroller.

Did you ever use microcontroller? Show some source code.

Or nobody can advice you. They can not know your level of experience.

18. ### ActivePower Member

Mar 15, 2012
155
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Have you taken a basic computer organization/architecture class? Most college-level Computer Architecture textbooks have a basic CPU design (ALU, memory and all).

The classic MIPS CPU architecture has long been detailed in various editions of Hennessy and Patterson's excellent book on the subject. The book itself is worth purchasing but if you want to avoid buying it you can easily find numerous resources on the web explaining the modelling of a rudimentary CPU design in Verilog/VHDL (and even some Verilog code). Here is one course website I have bookmarked in my browser.

This Google search itself contains some sources you could get started on. Also look up Jan Gray's fpgacpu.org - it contains a pdf paper series with detailed instructions and good pointers to get your design onto a FPGA/CPLD and even write an associated assembler!

Hope this gets you started.

absf, vead and kubeek like this.

Nov 24, 2011
621
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I have done little work

micro controller design

8 bit micro controller
8 bit CPU
8 bit ALU
8 bit decoder
8 bit data
8 bit instruction
64 k program memory
64 k data memory
8 bit port input
8 bit port output
16 bit timer

Is it correct specification for 8 bit micro controller ?

20. ### takao21203 Distinguished Member

Apr 28, 2012
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no it's incorrect.

How about opening a blog (wordpress, altervista, blogspot etc.), doing some actual work, and then discussing your stuff, and how you can archieve further goals?

It is not correlating.

8 BIT MICROCONTROLLER is just saying, the data width is 8bit.

Instructions will use 8bit operands, but there could be some 16bit one's, using two 8bit registers.

Like kind of a "class". A Ford Fiesta is not a Mercedes 300SL and is not a mountainbike.

SPECIFICATION
is the definition what is the input data, the existing operations and the way they are implemented, and the ususal field of application. It is also called "the Architecture".