Hardware-agnostic C89 library for tracking battery State of Charge (SoC) via Riemann sum integration of power (Coulomb counting variant).

The library accumulates energy counts by integrating reported voltage and current over a defined time interval.

• Integration: _energy_accum += voltage * current performed every update_interval_ms.
• Recalibration: Forced synchronization to 100% SoC occurs if _max_energy_trigger is high for $\ge 5000\text{ms}$.
• Safety: Hard clamping of _energy_accum between $0$ and max_energy_wh.
• Data Integrity: Updates halt if report_timeout_ms is exceeded without a fresh call to chgc_set_voltage_V or chgc_set_current_A.

1. chgc_init(struct chgc *self): Zeroes all internal timers and accumulators.
2. chgc_set_config(struct chgc *self, const struct chgc_config cfg): Sets operational parameters. Only permitted once (fails if max_energy_wh > 0).

• chgc_set_voltage_V(self, val): Ingests raw scaled voltage; resets report timer.
• chgc_set_current_A(self, val): Ingests raw scaled current; resets report timer.
• chgc_update(self, delta_ms): Increments internal timers. Executes integration if update_interval_ms is reached.

• chgc_get_soc_pct(self): Returns integer percentage (0–100).
• chgc_get_energy_wh(self): Returns remaining energy in Watt-hours.

/* Global */
struct chgc battery;
struct chgc_config cfg;

...

/* Setup */
	cfg.max_energy_wh      = 24000;
	cfg.update_interval_ms = 10u;
	cfg.multiplier_V       = 2u;
	cfg.multiplier_A       = 2u;
	cfg.report_timeout_ms  = 500u;

	chgc_init(&battery);
	chgc_set_config(&battery, cfg);

...

/* Loop (assumes 10ms delta (update interval)) */
	chgc_set_voltage_V(&battery, read_adc_v());
	chgc_set_current_A(&battery, read_adc_a());
	chgc_update(&battery, 10); 

Coverage report is available at: https://furdog.github.io/charge_counter/coverage/