I am tring to use a STM32F205ZGT6 MCU (Datasheet). I followed the datasheet as close as possible and made a schematic like below.
I have some questions about the design and why.
In the pin layout, there are 12 VDD and 11 VSS. How many decoupling capacitors should I use? Should I match it to the number of VDD or the number of VSS?
The 100nF decoupling capacitors are connected with a mysterious capacitor of 1uF or 4.7uF. What are these capacitors called and what do they do?
Some shematics floating in the internet uses inductors between VDD and the capacitors to make a low-pass filter. Is this strictly necessary? If so, what frequency should I set the cutoff to?