[2022-04-01] Engineering Project I2C GPIO M8 Connector Port Expander for Particle Tracker One Particle Tracker One Firmware v17 Device OS 3.2.0 LTE Cat M1 cellular modem GNSS Supports: GPS , SBAS, QZSS, GLONASS , BeiDou, and Galileo with up to 1.8m accuracy and untethered dead-reckoning Support for CAN bus and 5V boost power for CAN devices.  This CAN_BUS_5V output via the M8 IP67 connection is what will power the port expander and subsequent devices down the line.  This eliminates the need for a mandatory external power supply, although keeping the tracker connected to vehicle power when available is always an option.  The CANbus boost power only supplies about 370mA so it is not exactly unlimited to say the least… M8 extension cable connected to left of micro USB3 cable:   The IP67 M8, 8-pin, male with threaded barrel connector pin specifications available by clicking the image:   Circuit Schematic for the Particle Tracker One uses an MCP23008T IC for I2C/GPIO