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8bit vs 32 bit Microntroller

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hioyo

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May I know when to use a 32bit microcontroller compared to an 8-bit microcontroller?

Can someone tell an application where both 8-bit and 32bit microcontrollers work

Some other application where only 32 bit microcontroller will work
 

The questions are quite broad, but here is a stab at it :

1) 32 bit processors generally birthed because of the need for computation speed and address
space size expansion over the years.

2) 8 bit processors due to cost (smaller die size).

3) Historically one used smaller processor in low power applications and driving cost.
But recent advances using memory processes to design/build processors have 32 bit
parts competitive in power for some applications. But all things equal an 8 bit and 32
bit in same process the 8 bit will drive cost due to lower die size, hence cost.

4) 32 bit processors, in general, have more and higher performance peripherals.

5) Generally speaking it take's a 32 bit processor to implement stacks in COM systems,
like ethernet. Or moderate to high end graphics or advanced signal processing.


Regards, Dana.
 
Hi,

there is no general rule.
Usually a 32 bit machine will have more throughput, but not always. It depends o a lot of things like
* hardware
* clock frequency
* microcontroller type (floating point support...)
* code
* compiler (options)
* periferals
... and so on

Examples:
* Polling a port pin: usually needs one command ... independent of 8bit or 32 bit
* Transferring one 32 bit variable of data form A to B... usually takes 4 x (R & W) on a 8 bit machine and 1 x (R & W) on a 32 bit machine.
* doing I2C communication: will be almost identically fast on both machines, because the bottleneck is the I2C bus.
(unless the machine uses ISR or FIFO or DMA ... which depends on microcontroller type and code)

But on average applications the 32 bit machine will be faster than an 8 bit machine.

In the 1980ies many home computers ran on an 8 bit machine. Keyboard, maybe mouse, monitor, Memory, printer...

And you could wirte a letter with it, or play a game.
Nowadays with extremely high resolution monitors and streaming videos it makes no sense to try to run this on an 8 bit machine.

There is no strict limit and there is no application that strictly needs 8 bit or 32 bit... the question is:
* what are the requirements. (Very, very important! Decide the requirements carefully)
* and how much effort you want to put in

If you are concerned about processing power
... then often it makes more sense to start with the 32 bit machine and maybe pay a bit more hardware cost,
...than starting with 8 bit ... to find out it´s too slow ... and then switch to 32 bit.

Klaus
 
You select the one (8,16, 32-bit, architecture, built-in modules etc.) based on the task at hand.
8-bit controllers are often good for control systems and low-level communications whereas 32-bit devices are good for number-crunching (as some have FPUs in them as well).
32-bit devices can be slower in some instances - e.g. if you are sending out a stream of 8-bit characters then 3 of the 4 will not be aligned on a 32-bit memory address boundary which can lead to additional processing (often in hardware admittedly) to extract the byte that is wanted from the 32-bit memory word; if you have to do that 3 out for the 4 times then that can slow things down. It all depends on the capability of the microcontroller architecture.
Cost can also be a factor as is PCB real-estate.
Susan
 
May I know when to use a 32bit microcontroller compared to an 8-bit microcontroller?

Can someone tell an application where both 8-bit and 32bit microcontrollers work

Some other application where only 32 bit microcontroller will work
32 bit is usually preferred when you need better speed. Mostly for ML, image processing etc.
 
And not to be outdone there are SOC parts with Dual Core 32 bit
processors on them.

1657738173108.png



And lest we forget ARM 64 bit processors, see attached.


Regards, Dana.
 

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Last edited:
RISC-V based systems are coming as well (you can even get open-source versions that run in FPGA devices!)
Susan
 

Hello!

RISC-V based systems are coming as well (you can even get open-source versions that run in FPGA devices!)

... but the hardest thing these days will be to find an FPGA.

Dora.
 

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