8 bit vs 32 bit

EDAboard.com Forum Index -> Microcontrollers -> 8 bit vs 32 bit

Author

Message

alexz

Joined: 19 Nov 2004
Posts: 286
Helped: 3
Location: UK

19 Jul 2007 7:26 32 vs 8 bit micro

What cas you say about the preferences in selection the micro?
What are the advantages of 8bits over 32 bits accept that a lot of material like reference design, code examples, cheap emulators and compilers ?
What else can you add?
What are the disadvantages of 32 bits over 8bits?

neoaspilet11

Joined: 29 Sep 2005
Posts: 276
Helped: 21
Location: Cebu, Philippines

19 Jul 2007 7:41 choosing 8 vs. 16 vs. 32 bit

That really all depends in what is your application. If your application is computationally extensive such as DSP, arithmetic etc, 16 or 32 bit processing is preferrable.

If your application do not require much arithmetic, such as text processing, I would choose 8-bit micros. They are simple and cheap. They even can come into DIP package which can be rapidly prototyped. And teher a alot of proven good simulators of 8 bit micro which makes code development even faster.

Google
AdSense
Google Adsense

19 Jul 2007 7:41 Ads

vinseth

Joined: 06 Jul 2007
Posts: 37
Helped: 3

19 Jul 2007 8:05 8-bit vs. 16-bit vs. 32-bit

It depends on the application you want to develop.Check if this link helps, it shows advantages of 8bit micro. ,just on the surface Sad

.

http://www.eetimes.com/showArticle.jhtml?articleID=54202120

bobsanjose

Joined: 13 Jan 2006
Posts: 264
Helped: 25
Location: SF-Bay

19 Jul 2007 18:46 microcontroller good development tools

As already mentioned, it all depends on your application:

Advantages 8-bit:
Simplicity!!
Small packages
Wide voltage ranges (e.g. 1.8V - 5.5V)
More complete systems on chip, does not need (many) external components.
Usually very good in bit manipulation

Advantages 32-bit:
Performance
Price/performance
can be lower price if memory is large (>=64KB)
Will be driver of innovation

Disadvantages 32-bit:
Complexity
Longer learning curve / time to market
More components on the board needed.
Usually no 5V option for I/O or ADC
Mostly less drive capability for port pins.

So, there are reasons to use an 8-bit over a 32-bit but if your application might need the performance of a 32-bit soon, I would use the 32-bit from the beginning. .

Hth Bob

kmr

Joined: 23 Feb 2007
Posts: 4

20 Jul 2007 4:00 the disadvantage of 32 bit architecture

I'd add one more disadvantage to 32-bit: usually more flash memory required to store your program.

folks

Joined: 30 Oct 2006
Posts: 183
Helped: 18
Location: Guadalajara

20 Jul 2007 6:17 8-bit soc

Hi all.
bobsanjose, you do not mention disadvantages for 8 bits and here are:

*- 8 bit width
*- Poor memory (some do not have expand memory)
*- Less ports
*- The most not optimize in C.
*- Less peripherals.
*- Less MIPS.
*- For small projects
*- The most important: Microcontroller are inherently different (With very few exceptions, software written for a microcontroller from one companie will not work on a microcontroller from other companies)

Regards

bobsanjose

Joined: 13 Jan 2006
Posts: 264
Helped: 25
Location: SF-Bay

20 Jul 2007 22:00 8 bit vs 32 bit

Hi folks,

I did not mentione the disadvantages for 8-bit because I did read the question and this was not part of it Wink

btw. I disagree with the "less peripherals part"
Also on 32-bit most projects are done on 32-bit microcontrollers and your most important disadvantage applies for 32-bit just as much as for 8-bit, they are not compatible.

Bob

folks

Joined: 30 Oct 2006
Posts: 183
Helped: 18
Location: Guadalajara

20 Jul 2007 23:15 Re: 8 bit vs 32 bit

bobsanjose wrote:

Hi folks,

I did not mentione the disadvantages for 8-bit because I did read the question and this was not part of it Wink

Hi bobsanjose
"ARM has created a efficient design that is used by many semiconductor suppliers as the core of their microprocessor or microcontroller (Even companies with their own competing design have licensed the ARM)."
Then you can change to other company and do not modify your source program. This is the most important advantage.

best wishes

alexz

Joined: 19 Nov 2004
Posts: 286
Helped: 3
Location: UK

21 Jul 2007 7:14 Re: 8 bit vs 32 bit

folks wrote:

(Even companies with their own competing design have licensed the ARM)."
best wishes

What is the reason for this?

folks

Joined: 30 Oct 2006
Posts: 183
Helped: 18
Location: Guadalajara

21 Jul 2007 8:14 Re: 8 bit vs 32 bit

alexz wrote:

folks wrote:

(Even companies with their own competing design have licensed the ARM)."
best wishes

What is the reason for this?

The first reason is because the companies intend for integration by semiconductor (CORE) and the second is because ARM has created a very compact, efficient and powerful desing.
Today, Portable electronic devices are ARM powered:
http://www.arm.com/markets/holidaygifts/

Regards

alexz

Joined: 19 Nov 2004
Posts: 286
Helped: 3
Location: UK

21 Jul 2007 8:26 Re: 8 bit vs 32 bit

I am wondering why do other semiconductors companies such as NEC produce SoCs with ARM core if they have their own NEC's core ?

alexz

Joined: 19 Nov 2004
Posts: 286
Helped: 3
Location: UK

21 Jul 2007 21:29 Re: 8 bit vs 32 bit

There is some more information:

The right microcontroller selection is based on the combination of on chip peripherals, memory size, I/O match the system requirements, performance, the cost, power consumption, development time and availability of good development tools.
The actual core preference takes the lowest percentage.

Software development, debugging and maintain are the primary drivers of project cost and schedule. The key criteria here is the project reuse, the ability to spread the software development investment across multiple products.

Adapting off-the-shelf solution reduces development time. Industrial control applications, where 8 bit micros are very popular, fall into this category, since the volumes are high. Moving to high level programming languages and robust development tools, enable the software reuse.
Modern 32 bit microcontrollers enable optimizing the architecture using powerful debugging tools minimizing the need for assembly code.

Power consumption:
Selecting a microcontroller requires an evaluation of power consumption of both active and standby. CPU core is a very small contributor to total active power consumption when peripherals, memory and I/O are considered. Looking at the 8 bit and 32 bit architectures, it is clear that 32 bit SoC are very hungry for power because of the powerful CPU and everything else on chip.
The average power consumption though is the duty cycle time spent in sleep mode and active mode.
Because 32 bit operates faster, it can execute a task and go back to sleep much faster then an 8 bit one. Hence spending more time in standby mode and saving more power.

Code size:
As know CISC CPU consumes less program memory then RISC. However, good 32 bit compilers generate less code, hence using less program memory.

Looks like the conclusion, is to go for 32 bits even if the application is low-end.

Please feel free to add your comments