MAX17205 Battery Gauge Driver

The max17205.c module implements the I2C driver for communicating with the Maxim Integrated MAX17205 battery fuel gauge IC.

Features

• Voltage Measurement: Uses a 1.25mV LSB scaling from the BATT register.
• Current Measurement: Extracts both instantaneous and device-averaged current from the CURRENT and AVGCURRENT registers.
• State of Charge (SOC): Provides a precise percentage based on the ModelGauge m5 algorithm from the REPSOC register.
• Capacity: Retrieves remaining capacity in mAh.
• Time Estimates: Retrieves Time-to-Empty (TTE) and Time-to-Full (TTF) estimations.

Initialization

The max17205_init function configures the device parameters according to the specific battery pack size (design_capacity_mah) and the shunt resistor (rsense_mohm):

• It calculates and writes to the DesignCap register using the primary I2C address (0x36).
• It calculates and writes to the nRSense register using the extended I2C address (0x0B).

Hardware Interface

Communication is strictly via the STM32 HAL I2C API (HAL_I2C_Mem_Read and HAL_I2C_Mem_Write). The driver implements separate helpers for primary and extended I2C address spaces required by the MAX17205's register layout.