Some nets are marked slightly differently between the silkscreen on Rick and in the schematic.
Schematics
Translations
Shown on Schematic
Shown on the PCB
VMTR is one of the two 5 volt busses, specifically for the motors+5VM
SERVO_nS Are the n servo current sense netsMGND
SERVO_nC Are the n servo control/signal netsSIGn
RX_1, TX_1 Are the main serial pinsRX, TX
SDA_1, SCL_1 Are the main I2C pinsSDA1, SCL1
SDA_2, SCL_2 Are the secondary I2C pinsSDA2, SCL2
CHG_INCHG+
BATT_INBATT+
GND Common groundCHG-, BATT-