TODO

ALIVE:
  * FTDI UART is alive (modulo known issue below with voltages)
  * SWD is alive using ST-LINK v2
  * nRF52840 CPU is alive
  * nRF52840 high-speed crystal is alive
  * nRF52840 radio (Bluetooth LE) is alive
  * MAX14745 is alive and speaking I2C, buck regulator is alive
  * IMU is alive and speaking I2C
  * Pressure sensor is alive and speaking I2C
  * display
  * LEDs
  * nRF52840 DC-DC buck converter
  * Maxim LDO
  * Maxim buck
  * buttons
  * microphone
  * QSPI flash
  * vibrate driver I2C
  * vibrate driver output
  * Maxim charge circuitry
  * part 1 of max14745 power button ECO (cut trace to nRF; did not add 100k in series yet)

STILL TO CHECK OUT:
  * magnetometer
  * part 2 of ECO for max14745 power button issue

KNOWN ISSUES:
  * FTDI needs VDDIO tied to +3.3, and needs level shifter
  * FTDI SWD resistor is on wrong pin
  * display connector is rotated 180 degrees (should be OK because display connector is dual contact)
  * ambient light sensor footprint is mirrored
  * manufacturability issues on vias for SWD and PMIC I2C buses leading to shorts; vias should be moved further apart (can be worked around with scalpel on current revision boards)
  * I can't figure out where I put the third board from the first run
  * vibrate driver enable is tied to 0 instead of to Vdd
  * PMIC power monitor pin appears to be shorted to ground (was shorted on nRF side); CHICKEN4 is fine
  * nRF pulls power button low when nRF power is down; need to add 100k in series to nRF (means board will not ever wake up after being powered down with power button)

TRACKING:
  * still no life on magnetometer; i2c is toggling, not sure if it is responding or not (need logic analyzer)
  * battery only seems to charge at 50mA (maybe battery is just old)
  * max14745 needs charge control registers reprogrammed after every USBIN event