Electrical – Why choose an 8bit over a 32bit MCU


With the recent Cortex-M rage, there seems to be a lot of 8bit bashing going around.

I was wondering what specific use cases engineers encountered where 8bit MCUs were the preferred choice over 32bit, and what decisions informed their choice.

I think this information proves useful as an aid for others who need to make a similar choice between 8/32bit.

Best Answer

I was wondering what fellow engineers thought of 8bit MCUs, and why they would consider using one in their design over a 32bit MCU.

I'm a 32-bit guy by trade: worked a lot on earlier LPC and Luminary chips.

For most of what I do personally, I use 8-bit because they are sufficient. actually more than sufficient: many times I have to run the mcus at speed lower than their default speed settings.

8-bit mcus are simple to learn, inexpensive and best of all plentiful.

with that said, there are lots of demanding applications where a simple 8-bit mcu doesn't cut it. Or more precisely, doesn't cut it without serious additional investments in software. If you lots of number crunching, loads of multi-tasking (driving graphics for example), or into some specialized niches.

for what I do personally, 8-bit vs. 32-bit is fully transparent. to the point that I can run most of my 8-bit code on 32-bit, or vice versa, with minimum changes. I can even run my Arduino code on most 16/32bit mcus with minimum changes now.

so most of the time, what I pick on the hardware side is not even driven by software.

edit: as to your broader point of whether the 8-bit market is dying (commercially), I would say, based on my own experience, that it is definitely so.

10+ years or so ago, I was at a software house that offered a full range of support, from 8-bit chips to 32-bit chips. one of the earliest decisions I made was to analyze the profitability of each platform and as a result, we quickly dropped support for 8-bit chips, to the point that we want to get paid to upgrade our older 8-bit software and we provide no support going forward.

8-bit programmers have a hard time finding work and 32-bit programmers are in high demand. you can observe the same trend on the programming side, at embedded conferences. I went to a ST conference on their 32-bit offerings in Shanghai 10 years ago and was absolutely shocked by the many young faces there.

I think if you are an 8-bit programmer in a high cost area, you better have a niche or two. or you face some serious risks very soon.

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