[General] 8 Bit or 32 Bit Microcontroller

[K Srinivas Pavan Kumar]

Hi,
I have 1 question guys
8 bit microcontroller is working 32Mhz Frequency and 32 Bit icrocontroller is working with 8 Mhz frequency,which one is better in real time systems.

 

[K Srinivas Pavan Kumar]

8,16,32 bit controllers

What is the difference between 8,16,32 bit controllers ?

 

[Easyrider83]

Re: 8,16,32 bit controllers

Data and address bus wide
32bit can multiply long word values in 1 cycle. 8bit will require up to 64 cycles.
32bit mcu more suitable for DSP and RTOS usage - heavy applications.
8bit for toys and bacis automatics.

 

[Easyrider83]

Better means nothing. Question is too general.
Efficency? Current consumption?

 

[Warpspeed]

Depends what it has to do.

If its turning on a few lamps scanning a small keypad, and controlling a motor, 8 bits will be fine. It probably does not need to work on any more than eight bits each instruction.

If there is a lot of very fast intensive big number crunching, or requirements to manipulate images on a high resolution display, then being able to work on 32 bits simultaneously might speed things up enough to make it worthwhile.

 

[schmitt trigger]

Depends on the application.
If you are doing simple control systems like Tony mentions, a 32 bit controller is a serious overkill.

Just remember some of the early personal computers (i.e. Apple II) ran with an 8-bit micro clocked at 1 Mhz!

 

[D.A.(Tony)Stewart]

Depends on the application.
If you are doing simple control systems like Tony mentions, a 32 bit controller is a serious overkill.

Just remember some of the early personal computers (i.e. Apple II) ran with an 8-bit micro clocked at 1 Mhz!

I loved what one could do with the ][ + async/sync HDD controllers


In '79 we used 6800 to do custom RTOS, real-time digital telephony on DS1 /64kbps 8kHz frame rate with real time interrupts every 24 frames for stack swap and SCADA control.

 

[ads-ee]

Hi,
I have 1 question guys
8 bit microcontroller is working 32Mhz Frequency and 32 Bit icrocontroller is working with 8 Mhz frequency,which one is better in real time systems.

Returning to the original question...

One way to examine this scenario is the MIPs performance of the processor.
If both processors have similar average machine cycle per instruction performace (e.g. say it is 2 for both), then the 32-bit @ 8MHz will execute 4M instructions per sec, whereas the 8-bit @32MHz will execute 16M instructions per sec. If both processors are working with 8-bit data then obviously the 8-bit processor is going execute more instructions and perform much better than the 32-bit processor. If the data being worked on is 32-bit data then there is likely a crossover point where the performance of the 32-bit processor will exceed the 8-bit processor as all the extra instructions dealing with read/writing and managing four 8-bit values to do simple 32-bit arithmetic will eventually result in a significant number of clock cycles just manipulating the 32-bit data.

Another performance issue will be the amount of addressable memory for the 8-bit vs. the 32-bit processor.

 

[Warpspeed]

Another performance issue will be the amount of addressable memory for the 8-bit vs. the 32-bit processor.

Not only memory, but the i/o and any data bus also needs to be 32 bits wide to take full advantage of a 32 bit wide processor.

If every instruction requires four reads and four writes, to get data into and out of the processor, you would probably be better off with a faster 8 bit processor.