Dennis Field / dvk-mx8m-bsb - History

Move the charge controller, USB-C TCPC, and RTC to I2C1

Since each of these ICs will be powered at the same time as the SoM regardless of the PWR_EN state, they should share the same I2C bus as the PMIC.

Now using GPIO5_IO03 (P4.03) to put the class-D op-amp in shutdown and conserve energy when muted, make C1716 near the ETH PHY's DVDDL pin 47 220nF instead of 10uF (EmCraft suggested that this should be 100nF but their's is 220nF, asked why), added a 10k pull-down to PAM2841's ENA pin, added a 100nF cap to the smart card's C1 VCC pin, added a 1uF cap to the haptic motor circuit's 3V3_P rail

Still need to use I2C3 instead of I2C1 according to EmCraft's suggestions.

Rename all diff pairs such that they end in _P/_N rather than just P/N (underscore needed for diff pair routing)

Replace the tantalum capacitor that is AC-coupling the input of the class D amplifier with a ceramic 0603 cap

Replace resistors which have specific values that can be converted to more common values in order to reduce the total number of unique BoM line items

Replace the VCNL4040 proximity+ambient light sensor's 470nF bypass cap on VDD with a 1uF one to reduce the number of BoM line items, also replace the USB Hub+SDIO bridge chip's SDCD cap between the P-MOSFET's gate and drain with an 18pF capacitor instead of a 10pF for the same reason (reduce number of BoM line items)

Add proper WWAN reset circuit using a MMBT2222A NPN BJT along with a 100nF cap and a TVS diode, make needed adjustements to the WWAN's SIM card circuit (UIM-CLK and UIM-RESET caps are NC & added 4.7k series resistor to SIM_DETECT_O#), assign the MMBT2222A footprint to KiCad's official SOT-23 footprint (identical to the spec sheet's recommended land pattern)

If necessary, the NC cap pads on UIM-CLK and UIM-RESET can be tested with various values during the first prototype debugging phase.

Add pull-up resistor to nCS pin of the NOR flash chip, make electrolytic caps tantalums again due to a the price difference not being significant

Add mounting holes to the schematic and assign the associated M2 hole footprint, add fiducial marks to schematic and assign the associated 1mm diameter copper with 2mm diameter solder mask opening footprint, make various visual adjustments throughout the schematic

For better BoM generation, added placeholders for SOM, disṕlay, camera, WWAN card and wifi/BT card.
Datasheet links and supplier information can be stored in these new library symbols.