Battery curve

Conversion between battery voltage, charge percentage and time remaining. More...

Enumerations
enum	BatteryCurveVoltageCompensationKey { BATTERY_CURVE_COMPENSATE_STATUS_LED , BATTERY_CURVE_COMPENSATE_COUNT }
	Source of a voltage compensation. More...

Functions
void	battery_curve_set_compensation (BatteryCurveVoltageCompensationKey key, int mv)
	Set a compensation added to the measured voltage when computing the charge.
void	battery_curve_set_full_voltage (uint16_t voltage)
	Move the 100 % point of the discharge curve.
uint32_t	battery_curve_sample_ratio32_charge_percent (uint32_t battery_mv, bool is_charging)
	Get the charge for a voltage, applying the compensations.
int32_t	battery_curve_lookup_percent_with_scaling_factor (int battery_mv, bool is_charging, uint32_t scaling_factor)
	Get the charge for a voltage, scaled by a factor, without compensations.
uint32_t	battery_curve_get_hours_remaining (uint32_t percent_remaining)
	Get the hours of use left before low power mode.
uint32_t	battery_curve_get_percent_remaining (uint32_t hours)
	Get the charge needed for some hours of use before low power mode.
uint32_t	battery_curve_lookup_voltage_by_percent (uint32_t percent, bool is_charging)
	Get the voltage for a charge percentage.

Detailed Description

Conversion between battery voltage, charge percentage and time remaining.

The voltage curve backend uses per-board charge and discharge curves; with the nRF fuel gauge only the time remaining conversions are functional.

Enumeration Type Documentation

BatteryCurveVoltageCompensationKey

enum BatteryCurveVoltageCompensationKey

Source of a voltage compensation.

Enumerator
BATTERY_CURVE_COMPENSATE_STATUS_LED	Load of the status LED.
BATTERY_CURVE_COMPENSATE_COUNT	Number of compensation sources.

Function Documentation

battery_curve_get_hours_remaining()

uint32_t battery_curve_get_hours_remaining

(

uint32_t

percent_remaining

)

Get the hours of use left before low power mode.

Parameters

percent_remaining

Charge in percent, including the low power reserve.

Returns

Hours remaining.

battery_curve_get_percent_remaining()

uint32_t battery_curve_get_percent_remaining

(

uint32_t

hours

)

Get the charge needed for some hours of use before low power mode.

Inverse of battery_curve_get_hours_remaining().

Parameters

hours

Hours of use.

Returns

Charge in percent, including the low power reserve.

battery_curve_lookup_percent_with_scaling_factor()

int32_t battery_curve_lookup_percent_with_scaling_factor	(	int	battery_mv,
		bool	is_charging,
		uint32_t	scaling_factor
	)

Get the charge for a voltage, scaled by a factor, without compensations.

Interpolates linearly between curve points and clamps to the curve ends.

Parameters

battery_mv	Battery voltage in mV.
is_charging	true to use the charge curve.
scaling_factor	Value of 1 %.

Returns

Charge in units of scaling_factor per percent.

battery_curve_lookup_voltage_by_percent()

uint32_t battery_curve_lookup_voltage_by_percent	(	uint32_t	percent,
		bool	is_charging
	)

Get the voltage for a charge percentage.

Used by unit tests and QEMU.

Parameters

percent	Charge in percent.
is_charging	true to use the charge curve.

Returns

Battery voltage in mV.

battery_curve_sample_ratio32_charge_percent()

uint32_t battery_curve_sample_ratio32_charge_percent	(	uint32_t	battery_mv,
		bool	is_charging
	)

Get the charge for a voltage, applying the compensations.

Parameters

battery_mv	Battery voltage in mV.
is_charging	true to use the charge curve.

Returns

Charge as a ratio32.

battery_curve_set_compensation()

void battery_curve_set_compensation	(	BatteryCurveVoltageCompensationKey	key,
		int	mv
	)

Set a compensation added to the measured voltage when computing the charge.

For example, a constantly lit LED makes the measured voltage drop due to the internal resistance of the battery.

Parameters

key	Compensation source.
mv	Compensation in mV.

battery_curve_set_full_voltage()

void battery_curve_set_full_voltage

(

uint16_t

voltage

)

Move the 100 % point of the discharge curve.

Clamped so it stays above the next point of the curve.

Parameters

voltage

New 100 % voltage in mV.