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Notes on the BQ2013H Gas Gauge

The BQ2013H gas gauge was used to provide battery capacity feedback to the user. This IC measures the charge/discharge current and calculates the battery pack's capacity by accumulation. This IC was chosen for it's wide chemistry operation and high battery capacity support. As a lot of the Texas Instruments' gas gauges, the BQ2013H uses the signal wire HDQ communication protocol. A custom C++ HDQ library had to be written to support this protocol.

Library Usage
1. HDQ Library
2. BQ2013H Library
The HDQ Communication Protocol
Datasheet & Application Notes

Library Usage

HDQ Library

The microcontroller's UART being already used, HDQ was timing implemented on a discreet digital IO port.
Here is the usage documentation for the HDQ class:

/**
 * Constructor
 * @param pinArg: pin number to attach to
**/
HDQ(uint8_t pinArg = HDQ_DEFAULT_PIN);

/**
 * sendBreak: writes a break to the HDQ line
**/
void doBreak(void);

/**
 * write: send a payload to the device
 * @param reg: the address of the register to write to
 * @param payload: data to be sent
 * @return: false, unless if verif is set, then 
 *          it will read back the register and 
 *          return true if it matches the payload
**/
boolean write(uint8_t reg, uint8_t payload, boolean verif);
boolean write(uint8_t reg, uint8_t payload);

/**
 * read: read from the device
 * @param register: address of the register to read
 * @return a uint8_t integer
**/
uint8_t read(uint8_t reg);

BQ2013H Library

All of the IC's registers are implemented through the BQ2013H class.
The following shows a few of them through the usage example (using the Arduino API for serial UART output)

GASGAUGE.writeBatteryID(B11001001);

Serial.print("readBatteryID: ");
Serial.println(GASGAUGE.readBatteryID(), BIN);

Serial.print("Battery voltage: ");
float voltage   = GASGAUGE.readBatteryVoltage();
Serial.println(voltage, DEC);
uint8_t units   = (uint8_t) voltage/1;
uint8_t decimals= (uint8_t) (voltage - units)<<8;

Serial.print("Battery voltage: ");
Serial.print(units, DEC);
Serial.print(".");
Serial.println(decimals, DEC);

BQ2013H Function Prototypes

(Not fully documented yet)

boolean readChargeStatus(void);
boolean readBatteryReplaced(void);
boolean readValidDischarge(void);
// Returns VDQ & EDV1 with a mask of 0x03 where EDV1 is MSB and VDQ is LSB
uint8_t readEndOfDischarge(void);
uint8_t readTemperature(void);
uint8_t readAvailableCharge(void);
uint8_t readNominalCharge(void);
void writeNominalCharge(uint16_t nominalCharge);
uint8_t readBatteryID(void);
void writeBatteryID(uint8_t battID);
uint8_t readLastDischarge(void);
void writeLastDischarge(uint8_t lastDischarge);
boolean readChargeRate(void);
boolean readOverload(void);
/**
 * readProgramBit: read a program pin values (High, Low, Float);
 * @param pinNumber: the number of program pin (1 to 6);
 * @return: 0xFF on errors or depending of the state of the pin:
 *              - floating: 0x00
 *              - low:      0x01
 *              - high:     0x02
**/
uint8_t readProgramBit(uint8_t pinNumber);
uint8_t readOutputControl(void);
void writeOutputControl(uint8_t octlRegister);
uint16_t readOffsetAdjusment(void);
void writeOffsetAdjusment(uint16_t offsetMicroVolts);
float readSelfDischargeRate(void);
void writeSelfDischargeRate(float selfDischarge);
/**
 * readDigitalMagnitudeFilter: reads the current DMF
 * @return uint8_t: Vsrd & Vsrq threshold in µVolt
**/
uint16_t readDigitalMagnitudeFilter(void);
/**
 * writeDigitalMagnitudeFilter: writes a new DMF
 * @param srdqValue: DMF value in µVolt
**/
void writeDigitalMagnitudeFilter(uint16_t srdqValue);
uint8_t readLoadCompensation(void);
void writeLoadCompensation(uint8_t loadComp);
uint8_t readChargeCompensation(void);
void writeChargeCompensation(uint8_t chargeComp);
float readBatteryVoltage(void);
// Uses PPFC
void doReset(void);