sparkfun RTK Express Hook-Up Manual page 14

Fuel Gauge and Accelerometer
The MAX17048 is a simple to use fuel gauge IC that gives the user a statement of charge (SOC) that is basically a
0 to 100% report. The MAX17048 has a sophisticated algorithm to figure out what the SOC is based on cell
voltage that is beyond the scope of this tutorial but for our purposes, allows us to reliably view the battery level
when the unit is on.
The RTK Express also incorporates a the LIS2DH12 triple-axis accelerometer to aid in leveling in the field.
Qwiic
Two Qwiic connectors are included in the unit. The internal Qwiic connector connects to the OLED display
attached to the upper lid. The lower Qwiic connector is exposed on the end of the unit. These allow connection to
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the I C bus on the ESP32. Currently the stock RTK Express does not support any additional Qwiic sensors or
display but users may add support for their own application.