Dennis Field / dvk-mx8m-bsb - History

Length matching of SDCard signals.
Increasing distance between signals and creating meanders.

Increased distances of reduced gigabit media-independent interface (RGMII) signals
in order to be able to adjust trace lengths.

Add a 5.29x27.14mm Purism logo to the "back" silkscreen of the board, seen on the bottom left edge when facing the display, remove the old schematic rescue files which are remnants from the Kicad 5.0.0 upgrade

Re-route the USB hub+SD chip's crystal circuit making it more symmetric, extend the length of the ETH PHY's XTLI trace going to the crystal in order to more closely match its length to the XTLO trace

Place and route the remaining 5V_P bypass caps which are spread throughout various spots on the board, get the unrouted count down to 0

Now that the unrouted count is 0, it is time to clean up the entire layout; improving various routing such as separating the SIM card slot's CLK & data and making the USB hub+SD chip's crystal routing symnetric. After that, the BoM needs to be updated with the passive components' tolerances, capacitors' temperature & voltage ratings, and list recommended PNs which are shared with EmCraft's baseboard.

Move the two tantalum capacitors which were on the "back" to the "front" side, make corrections to the battery holder footprint including a hole which was missing for plastic pillar dealy (3D model contradicts the recommended footprint, may need to be adjusted depending on prototypes), place the 3V3_P and 1V8_P bypass caps throughout the board (as well as two of the 5V_P caps)

Only 8 more 5V_P bypass caps need to be placed and the unrouted count will be 0!

Move the speaker 1.2mm up and place the proximity/ambient light sensor just below the speaker

Use 5V_P as the inner plane AC-GND reference for the USB2 and USB smartcard diff pairs, move the C1821 electroyltic cap from the back side near the edge to the front under the SoM where there is space available, make the 3V3_P copper pour occupy areas which allow the C1822 electrolytic cap to have a lower impedance connection to the regulator and M.2/mPCIe loads (as well as bringing 3V3_P closer to other loads), create a large In3.Cu keepout area on the top of the board where the antennae are

Routing of 1V8_P net on In3.Cu layer and some other power signals.
Movement of other power nets to avoid crossing.
Change of polygon shape to prevent that they break in pieces.

Unrouted nets count is 60 (only capacitors outside board area).
Proximity sensor could be moved to even better position.

Moved proximity/light sensor to new position under the SIM socket.
(Other position can also be discussed).
Routed I2C3_SCL, I2C3_SDA and PROX_INT connectons.