12 Nov
2022
12 Nov
'22
4:08 p.m.
On Sat, Nov 12, 2022 at 11:59 AM Antonio Carlini via cctalk
<cctalk(a)classiccmp.org> wrote:
Surely a microcontroller is just a 555 with a few extra transistors?
For suitable (large) values of 'few'?
Actually I can think of many differences...
Firstly, the full equivalent circuit of the 555 is in the datasheet.
So I can predict how it should behave under all conditions (there are
many things you can do with a 555 besides astables and monostables). I
have never seen an equivalent circuit, or a gate level description of
a microcontroller.
All 555s are the same. If it fails I can replace it. Microcontrollers
cease to be the same once they are prgrammed. If a microcontroller
fails then I'm stuck. I won't be able to get the firmware
I would argue that 555s are a lot more reliable than microcontrollers.
And have a much longer life than the time to bitrot of most
microcontroller flash memories
It's a lot easier to test a 555 than it is to test a microcontroller.
555s do not have illegal internal states they can get into.
Microcontrollers almost always do. Hence the need for watchdog timers
which IMHO are a kludge,
Another tool in the box, just that it happens to be
very cheap.
Cheap != good
They have their uses. But like many tools they can be misused and often are.
-tony