Dennis Field / dvk-mx8m-bsb - History

Add current sense resistors and jumper symbols in the schematic, assign the various signals left unspecified, complete the PWR_EN assignment and verify that thepower sequence would be brought up in the correct order, add an LED to the VBAT_REG rail for debugging purposes (know when the board is receiving power)

Both the GP_LED1 and the HAPTIC motor are able to be controlled via PWM2 by individually MUXing the corresponding pads to PWM2. Only one pin should be MUXed to PWM2 at a time whilst the other is a GPIO, otherwise they will behave identically.

The I2C buses do not need the bus switch found on the EmCraft baseboard since the M.2 modules' power is controlled by PWR_EN and their I2C is level shifted between 1.8V<->3.3V, making it safe to leave them as is.

The various sense resistors have their corresponding parts selected but will be "NC" in the BoM and will not be assembled during manufacturing. To measure the current on the various rails (and WLAN M.2), one will need to break the trace between the two pads and place the corresponding resistor. A jumper (1.27 or 2.45 still needs to be determined) can be used to re-short these pads.

Notes have been added regarding which GPIO pins can easily be interchanged if it improves the layout.

Selected a better/cheaper RJ45 receptacle. Also picked out a well-suited green LED to be used in various spots throughout the board.

Include power load switch ICs to the 3.3V and 5V rails so that the SoC can disable the peripherals' power using the PWR_EN signal

Need to verify that 3V3's capacitance is greater than 3V3_P!

Next step is to have PWR_EN control the various logic translator chips EN pins.

Use a DP3T switch to select between eMMC, USB (serial download), and uSD boot devices, corrected the SW_BACK and SW_HOME buttons to have 33Ohm pull-ups instead
of pull-downs since the respective boot config lines have pull-downs already set

These buttons should be untouched during boot otherwise the board will not boot properly (pressing SW_HOME during boot causes "SD power cycle enable/eMMC reset enable" and pressing SW_BACK causes the uSD to be treated as a 4-bit bus if it's the boot device otherwise it's a BOOTCONFIG[6:4]=011 "reserved" condition)

Assign SAI5 to the WLAN/BT M.2, remove SIM2 slot due to conflicts between modules (specifically the L830-EB being a Config_0 module where the TX_BLANKING signal would connected to USIM_PWR2 sink), reassign the corresponding M.2 config pin to handle HP_DET, remove the AMOLED buck-boost as a different regulator will be used

The MIC_SEL, PROX_~INT, IMU_INT, and HAPTIC signals still need assigning

Add haptic/vibration motor circuit

Using a PFET to switch the high-side. The motor will likely be coin-shaped with adhesive on the back to stick to a designated spot on the board and have a 2-pin Molex or JST connector installed on the wire leads (by request).