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Comment by stackghost | Hacker News Reader

Obviously TFA is satire/tongue in cheek and while you can do all sorts of awesome stuff with a 555 you can't patch those implementations without physically rewiring them which in many cases means throwing out the board and fabbing a new one, whereas a microcontroller-based board can often be fixed with a simple jtag debugger.

So, yeah, 555 timers are cool and doing things with analog ICs is groovy but there's a reason everyone just stuffs a small microcontroller in places where we used to just stuff a 555, and it's maintainability.

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Two thoughts on situations where the 555 may be preferable, if anyone has experience how these compare :

1. Low-noise applications. I’d naively expect the 555 to be less noisy than a clocked digital microcontroller, though it’s been awhile since I’ve worked in this space.

2. Low power applications. How does latent power draw compare between a 555 and a typical low power microcontroller?

> Low power applications. How does latent power draw compare between a 555 and a typical low power microcontroller?

The 555 is very power hungry compared to a typical cheap low-power microcontroller. IIRC there are lower power variants but the 555 still fundamentally does timing by draining current through a resistor, which is going to result in losses.

A micro is far superior on both these metrics.

> I’d naively expect the 555 to be less noisy than a clocked digital microcontroller

TTL ones were exceptionally noisy because the output transistors "shot through" - both output transistors would conduct for a moment shorting the supply rail to ground and crowbarring ridiculous interference onto other parts of the circuit.

And there's another reason not to recommend them - no one sane has used the bipolar version since the Carter administration but they're still out there and it's another pitfall for beginners.

And price. A PY32 is about $0.08 in quantity and can do a lot more than a 555 - which is at least 3 times more expensive...

Puya? First time I hear of these things .. (having used ESP32, RPI Pico, Nordic and STM). Googling led me to OpenPuya https://py32.org/en/

Puya is a major flash manufacturer who ventured into ARM chips.

and it comes with new set of problems: Now you need a FW guys to write and maintain software for it, then your hardware team may need to wait that FW guy to release software to test, or the FW guy need to wait hardware to test his software, etc.

Then in production, you need another stage to flash the FW, which add time and complexity.

Then security, cheap MCU usually has bad software protection, that means your software can be read out easily, not a big deal since the FW replacing the 555 would be dead simple anyway, but try to explain it to a non-technical CEO when he read about it on his morning's newspaper.

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