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I don't want to create a stack for everything, but would be nice if somebody helps on figuring out why they read the AC input, why those holes between pads and why that broken tooth...
Probably to get 50 or 60 Hz for the timing reference for the clock and timer.
Even using a 4MHz crystal? I know old radio clocks use it for that matters (and I think it's a terrible solution), but if that's the reason would it really be necessary? I didn't connect this pin to the STM, but later was wondering if there is a smarter reason for it. Maybe to predict the best moment to switch on/off the Power relay? Perhaps as protection if the microwave generator works only in 50Hz or 60Hz?
Mains frequency is very accurate over the long term because power companies are obliged to produce the correct number of cycles in the long term. On the other hand just a little drift in the crystal frequency will make it slightly off, annoying the user.
It's not just a matter of getting cycles right. A power company that produces less cycles is cheating the consumer out of power.
If it uses solid state switching it needs to do it at zero crossing when turning on and off (possible lag is desirable for off to reach the lowest current in an inductive load)
A MCU that's a bit long in the 2th? Sorry, bad pun.
Looking at where it came from you may not have much luck identifying it. It's probably a proprietary MCU for running this appliance and probably has mask ROM.
I think the best you can do is try to work out what control signals are required to do what and replicate the functionality. You may need to cook a lot of chickens during experimentation. 😆
Yeah, I thought about the proprietary MCU and for this reason didn't search much... I'm not willing to measure all signals, but might use the chickens anyways hahaha
Now I saw the 22th! but it didn't stop me writing "fluent English" on my cv hahaha
By the way I love the city you came from. Visited it some 20 years ago. Jaime Lerner is one of my heroes.
You are Gabriel D'Espindula: Electronics lover, excited to create things and learn new technologies!
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