Can you tell my how many capacitors, by pinout, at a minimum or by range, are needed per MCU?

[SFern.10]

I am working on a way to characterize how many capacitors one might need when using a microcontroller. I've seen an incredible variety, but I'm curious if there are any ways of determining by assessing number of power pins and I/O if a range or minimum number of caps can be concluded. Can anyone help?

[MikeDB]

One 100nF good quality ceramic per VDD pin, plus a 4.7uF ceramic somewhere very near by, or two for the faster processors on opposite sides of the MCU.

And obviously one on each of the Vcap pins.

Leave even one off and trust me it will bite you.

But you don't need more than that either as I've seen in several ST app notes.

[S.Ma]

Still valid as physics based. Current loops and 200ps/inch

https://www.amazon.co.uk/High-Speed-Digital-Design-Semiconductor/dp/0133957241/ref=sr_1_1?keywords=black+magic+electronics&qid=1554054078&s=gateway&sr=8-1

Blinking 20 LED from STM32 or just reading I2C sensors will definitely change the power droops.

Skewing PWM, ground bounce topics... hmm...