Dennis Field / dvk-mx8m-bsb - History

Add built-in speaker and class-D amplifier to drive it from lineout, use an anal
og SPDT switch to select internal or external mic via software (GPIO), select sp
ecific 8Ohm SMD speaker and SMD -37dB passive 2 terminal microphone (2.2kOhm output impedance)

Introduce a method to switch between built-in and headset microphone depending on the presence of something plugged into the 3.5mm headphone jack, included notes regarding measurements, simulations, and various findings for the headset/built-in mic opperation

Zener diode included to protect the GPIO pin against under/over voltage from HP_OUT. Schmitt-trigger inverted at the enable pin of the analog switch for some debouncing.

Continue with the audio CODEC schematic, selected a potential STIA 3.5mm headphone jack, use logic level shifters on the WWAN/BT M.2's UART and PCM interfaces since the M.2 spec states that these are 1.8V logic levels

Still need to assign the corresponding SAI interface for the BT.

Include RJ45 connector selection information (likely using JD1-0001NL)

Add ethernet PHY schematic, assign the RGMII signals, and include its associated 48-QFN footprint