555 Timer Circuits

Not only are cheap microcontrollers often an easier choice for things the NE555 might be used for, they often draw far less power as well. I personally prefer to use an even smaller and cheaper micro like the ATTiny13A. It's also worth noting that your traditional 555 timers don't like to run below 5V, for that you'll need something like an LMC555. If you're building up a parts inventory, it often makes sense to have a bunch of very cheap micros rather than special purpose parts.

Could always use a 555 as a charge pump for your micro power mcu too.

Indeed, a small $0.23 mcu may have its own internal RC oscillator, or even a MEMS based resonator on a PLL. =3

The main advantage of 555 timer is that it is configured with a resistor/capacitor kit. No computer or programming required.

Microcontrollers obviously have more than 1 bit of memory + 2x analog comparators + one 33% / 66% voltage divider (which is all a 555 timer truly is).

What is surprising however is how flexible 1 bit of memory + 2x analog comparators + one 33% / 66% voltage divider

Another way of looking at it is the 555 is useless without multiple extra parts, where as most MCUs can operate with only a bypass cap (and even that is often optional in practice). But you do have to buy a programmer ($5 these days) and get comfortable with firmware, which puts some analog folks off. I'll admit that there is a certain elegance and appeal to using only parts you fully understand and nothing extraneous.

Except, it's not an advantage in any practical sense. Programmers cost pennies, toolchains are free and easy to use, and there are ample examples for simple tasks such as "toggle a pin in a particular way". The overall learning curve is almost certainly less steep than the learning curve for all the modes and quirks of the 555.

What matters in production is that a 555-based circuit will use more power, that it's four components to source and install instead of one, and so on. Don't get me wrong, I like the 555, just like I like vacuum tubes, but it's nearly as dead.

Even if you have a microcontroller, there are simple situations where the 555 can come in handy.

For example, switch debouncer could be solved in code, resistor+capacitor or other methods. But you know what's one of the best performing switch debouncers?

1-bit of memory with an analog comparator. Aka: a 555 Timer.

> 555 is useless without multiple extra parts

Not needed for bistable multi vibrator (aka: just a flip flop mode). Which happens to be the debouncer circuit.

"that it's four components to source and install instead of one,"

The ATMega needs about ten components to get properly operational for programming vs a simple 555 timer circuit. Oh, and then you also need the programmer and toolchain for making the code.

Or you can just use some basic math and thrown down native hardware to do the job. One of the biggest off-road lighting manufacturers on the planet does exactly this with 555 timers.

I manufacture lighting controls of various sorts as my current profession.

I'm curious what the circumstances are where that would be worth the extra BOM count if you're already feeding the input into a microcontroller. Needing to detect extremely short pulses where you can't spare a pin interrupt? Something else I can't think of?

Black Box engineering.

You can add the 555 Timer to an already completed design if it is later discovered that debouncing was an unsolved problem.

I don't think it is always appropriate to assume that code can be rewritten (or rearchitected) to fit your needs. Sometimes its easier to solve problems with a touch of extra external hardware.