PCB v3

[gauteh]

• Regulator for Notecard + rest of devices (@zerblatt007 )
• u.fl connectors for antennas
• matching network for antennas (@zerblatt007 )
• USB ports (@zerblatt007 )
• Check precision of crystals etc
• Check spacing notes for ISM330DHCX
• Debug LED (@zerblatt007 )?
• Add magnetometer (@gauteh)?
• External GPS (@gauteh )?
• Connect restart pin from notecard to artemis (@gauteh)
• Add USB-to-serial to ambiq (@zerblatt007 )

Closes #163

[jerabaul29]

One comment as an "external" user: if we would think about "industrializing" this or a later version at some point (I would be happy to take care of this :) ) for example using LabMaker (similar to https://www.labmaker.org/products/openmetbuoy ), it would be great to provide as many Artemis pins as possible to the end users to make it customizable - the idea being that if LabMaker or similar would start producing SFYs, then they will not want to do fast iteration of the PCB, so if some users want to customize it, additional pins would be useful :) .

I understand that space is very limited, but if there is possibility to "break out" some unused pins on either "through hole pin headers", or even just through "pin pads" (for saving space), that would be great :) . For example offering an unused I2C, unused SPI, unused serial, a couple of analog pins, a couple of digital pins, would be great if doable :) .

[jerabaul29]

(for industrializing at LabMaker, it would be very useful too if the SFY could be programmed over USB-C directly - not sure if / how easy this would be doable :) ).

[jerabaul29]

(as a note, if the "adding broken out pins" aspect is doable / relevant, an example of "pin pads" on the circumference of a board; in case this can be a space effective solution :) "usual" flat pads on the top or bottom layer could also work fine of course :) )