BQ25895M

The BQ25895M is switch mode battery charge management and system power path management device for single cell Li-Ion and Li-polymer batteries. It supports high input voltage fast charging and communicates over an I2C serial interface.

Class Usage

Constructor: BQ25895M(i2cBus [,i2cAddress])

The class’ constructor takes one required parameter (a configured imp I²C bus) and an optional parameter (the I²C address of the BQ25895M. The I²C address must be the address of your chip or an I²C error will be thrown.

Parameters

Parameter	Type	Required	Description
i2cBus	i2c bus object	Yes	The imp i2c bus that the BQ25895M is wired to. The i2c bus must be preconfigured. The library will not configure the bus.
i2cAddress	integer	No	The i2c address of the BQ25895M. Default value is 0x6A

Return Value

None.

Example

local i2c = hardware.i2cKL
i2c.configure(CLOCK_SPEED_400_KHZ);
batteryCharger <- BQ25895M(i2c);

Class Methods

initCharger()

Initializes the battery charger with default settings. This method must be called before any other.

Return Value

None.

Example

batteryCharger.initCharger();
// Initializes charger with default settings

enableCharging()

Enables the device to automatically perform a charging cycle when a battery is connected and an input source is available.

Parameters

None.

Return Value

None.

Example

batteryCharger.enableCharging();
// Enables charging

disableCharging()

Disables charging capabilities from the device. The device will not charge until enableCharging() is called again.

Parameters

None.

Return Value

None.

Example

batteryCharger.disableCharging();
// Disables charging

setChargeCurrent(milliAmps)

This method sets the fast charge current limit.

The default fast charge current limit is 2048mA.

Parameters

Parameter	Type	Required	Description
currentLimit	Integer	Yes	The desired ce in milli Volts (3840 - 4608mV)

Return Value

None.

Example

batteryCharger.setChargeVoltage(4200);
// Sets the charge voltage to 4200mV

setChargeVoltage(volts)

This method sets the desired battery voltage that the device should charge to.

The default charge voltage is 4352 mV.

Parameters

Parameter	Type	Required	Description
chargeVoltage	Integer	Yes	The desired fast charge current limit in milli Aolts (0 - 5056mA)

Return Value

None.

Example

batteryCharger.setCurrentLimit(5056);
// Sets the fast charge current limit to 5056mA

getChargeVoltage()

Returns the target battery charge voltage

Parameters

None.

Return Value

Integer — The voltage in milli volts.

Example

local voltage = batteryCharger.getChargeVoltage();
server.log("Voltage: " + voltage + "mV");

getBatteryVoltage()

Returns the current battery voltage based on the internal ADC conversion.

Parameters

None.

Return Value

Integer — The battery voltage in milli volts.

Example

local voltage = batteryCharger.getBatteryVoltage();
server.log("Voltage: " + voltage + "mV");

getVBUSVoltage()

Returns the VBUS voltage based on the ADC conversion, this is the input voltage

Parameters

None.

Return Value

Integer — The battery voltage in milli volts.

Example

local voltage = batteryCharger.getVBUSVoltage();
server.log("Voltage: " + voltage + "mV");

getSystemVoltage()

Returns the system voltage based on the ADC conversion, this the output voltage which can be used to power other chips in your application

Parameters

None.

Return Value

Integer — The battery voltage in milli volts.

Example

local voltage = batteryCharger.getSystemVoltage();
server.log("Voltage: " + voltage + "mV");

getChargingCurrent()

Returns the measured current going to the battery

Parameters

None.

Return Value

Integer — The charging current in milli Amps.

Example

local current = batteryCharger.getChargingCurrent();
server.log("Current: " + current + "mA");

getChargingStatus()

Returns the charging status

Parameters

None.

Return Value

Integer — Not Charging = 0, Pre-charge = 1, Fast Charging = 2, Charge Termination Good = 3

enum chargingStatus{
    not_charging, // 0
    pre_charge, // 1
    fast_charging, // 2
    charge_termination_done // 3
}

Example

local chargingStatus = batteryCharger.getChargingStatus();
server.log("Status: " + chargingStatus);

getChargerFaults()

Returns the possible charger faults

Parameters

None.

Return Value

Table — the possible charger faults

Fault	Type	Description
Watchdog Fault	Bool	true if watchdog timer has expired
Boost Fault	Bool	true if VBUS overloaded in OTG, VBUS OVP, or battery is too low
Chrg Fault	Enum	*enumerated type
Batt Fault	Bool	true if VBAT > VBATOVP
NTC Fault	Enum	*enumerated type

*CHRG_FAULT has an enumerated type to match its output.

enum chargingFault{
    normal, // 0
    input_fault, // 1
    thermal_shutdown, // 2
    charge_safety_timer_expiration // 3
}

*NTC_FAULT has an enumerated type to match its output.

enum ntcFault{
   normal, // 0
   ts_cold, // 1
   ts_hot // 2
}

Example

local chargingStatus = batteryCharger.getChargerFaults();

setDefaults()

Restores the devices default settings

Parameters

None.

Return Value

None.

Example

batteryCharger.setDefaults();