This fascinates me. Is there a website anywhere that is collecting these sorts of use cases? It seems truly mind blowing something as simple as an electric toothbrush would have a processor in it.
Think about your toothbrush. All important timing parameters are configured digitally and you can easily change it. You can technically do the same with resonators but it would take much more board space, be less precise, require inductors which you want to avoid in the circuit, etc.
> You can technically do the same with resonators but it would take much more board space, be less precise, require inductors which you want to avoid in the circuit, etc.
Not only do you save the costs of using a crystal, you also save two pins - which was useful in the days of 8-pin microcontrollers like the ATtiny85.
As internal RC oscillator drift rates can be as much as 10% (and vary with temperature) they're not precise enough to run a serial connection, let alone a USB connection. That's why products like Arduino tend to go directly to using a proper crystal (which gives you a 0.01% drift rate for a few pennies).
Every chip brand would have their own protocol and provide their own programming hardware that could speak it.
You can also, well, use a regular toothbrush. What is actually important in a toothbrush has nothing to do with electronics.
No, I don't need any special functionality other than to clean my teeth but if you were to design a toothbrush you would most likely be asked to implement those.
I doubt, pretty much anything that has electronic circuitry has got a micro processor - it's an off the shelf component, well understood, much easier to change/modify and test than custom built analog circuitry. For example - what's the option to save any end user settings with analog devises - knobs/potentiometers.... Compared non-volatile memory like NAND, the cost (and space and weight) differences are orders of magnitude.