Greetings! My name is Adam. This is my first post. =)

Hopefully someone out there can give me a hand.

I have been attempting to design a board for the STM32F4 in 4-layers which I plan to order from OSHPark.com. Why 4-layers? My goal is to see if I can get the UFBGA-176 chip booted. That's it! There is no other goal other than assembling the board with the BGA chip and blinking an LED with it.

In some examples I have found online there is a capacitor between the VDD (3.3v) and GND on each VDD output on the chip. Most of the VSS (GND) pins on the chip are a cluster of 25 pins in the middle and a few others scattered around.

Is it necessary to connect every VSS and VDD pin (ball) to boot?
Are the capacitors necessary to boot?

You guys rock!

-Adam

 

1) Yes, unless you are willing to buy countless 4 layer PCBs in the experiment to determine what is the fewest or most essential connections.

2) Yes, unless you desire inconsistent to non-existent performance.

(Where was my post on doing what Simon sez?)

 

That was an insanely quick response Ernie! And also the one I was expecting. 8)

Just after I made my post I realized those are decoupling capacitors, just read the wiki. Learn something new every day!

I'm thinking maybe I can get away with *less* decoupling capacitors. They REALLY complicate my board layout and routing because of the difficult UFBGA-176 package.

That is interesting regarding the performance. Not supplying VDD to every pin won't actually cause the chip to "never boot" but will just starve it for current? Interesting!

Thanks for help and insanely fast reply! =)

-Adam