From: Randy Dawson <rdawson16@hotmail.com>
To: Microcontroller discussion list - Public. <piclist@mit.edu>,
	"joshybear@gmail.com" <joshybear@gmail.com>
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Date: Sat, 12 Sep 2020 18:32:17 -0700
Subject: Re: [EE] Four Layer Routing Strategy
Thread-Topic: [EE] Four Layer Routing Strategy
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Hi Josh,

Lets simplify things.
Use your two inner layers for the ground and power (your 3.3V)
The top and bottom are for your signal routes.
A strategy to use, would be for one layer, the top, to be horizontal traces=
, and the bottom to be the vertical traces.
It is called 'Manhattan routing'.
Its just like driving in the city, you go as far as you can to your destina=
tion (on top), turn the corner (drop a via) to the bottom, to go vertical t=
o complete the route your destination.

Randy

________________________________
From: piclist-bounces@mit.edu <piclist-bounces@mit.edu> on behalf of Josh K=
offman <joshybear@gmail.com>
Sent: Saturday, September 12, 2020 10:10 AM
To: Microcontroller discussion list - Public. <piclist@mit.edu>
Subject: [EE] Four Layer Routing Strategy

Hi all,

I'm working on my first 4 layer board. I feel a bit like I failed
cramming it all into two layers, but I recognize that having so many
vias on every trace would be less than ideal.

I'm using top and bottom for signals, then the inner layers for power.
The board isn't anything crazy RF, just some regular digital signals.
There is some digital audio on the board, so there are a few "medium"
frequency traces.

I plan on using the top inner layer for ground. I'll do it like I
normally do, which is to route the ground traces manually, then do a
pour that connects to the ground trace in one place.

On the bottom inner layer I'm going to route my 3.3V traces. There
will be a lot of free space on that layer.

So the question is, what should I do with the free space on the 3.3V
layer? I could do either a 3.3V pour or another ground pour. I lean
towards another ground pour but I don't want to inadvertently create a
weird capacitor.

Any suggestions? Since this is my first time I'd like to not have to
re-make the board because of this particular error!

Thank you!

Josh
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