NPM1300 Arduino Library

A lightweight Arduino library for the Nordic nPM1300 Power Management IC.

Features

• BUCK1 and BUCK2 voltage control (1.0V - 3.3V)
• Battery voltage, current, and temperature monitoring
• State of Charge (SOC) reading
• Charging control and status
• Simple Arduino-style API
• I2C communication

Installation

Arduino IDE

1. Download this repository as a ZIP file
2. In Arduino IDE, go to Sketch > Include Library > Add .ZIP Library
3. Select the downloaded ZIP file
4. Restart Arduino IDE

Manual Installation

1. Download this repository
2. Copy the NPM1300 folder to your Arduino libraries directory:
   • Windows: Documents/Arduino/libraries/
   • Mac: Documents/Arduino/libraries/
   • Linux: ~/Arduino/libraries/
3. Restart Arduino IDE

Hardware Connection

Connect nPM1300 to Arduino via I2C:

• SDA to Arduino SDA pin
• SCL to Arduino SCL pin
• GND to Arduino GND
• Default I2C address: 0x6B

Quick Start

#include <NPM1300.h>

NPM1300 pmic;

void setup() {
    Serial.begin(115200);
    
    // Initialize nPM1300
    if (!pmic.begin()) {
        Serial.println("Failed to initialize NPM1300");
        while (1);
    }
    
    // Configure BUCK outputs
    pmic.writeBuck1(3.3);  // Set BUCK1 to 3.3V
    pmic.writeBuck2(1.8);  // Set BUCK2 to 1.8V
}

void loop() {
    // Read battery voltage
    uint16_t voltage = pmic.readVBAT();
    Serial.print("Battery: ");
    Serial.print(voltage);
    Serial.println(" mV");
    
    // Read battery percentage
    uint8_t soc = pmic.readSOC();
    Serial.print("SOC: ");
    Serial.print(soc);
    Serial.println(" %");
    
    delay(1000);
}

API Reference

Initialization

bool begin()

Initialize the nPM1300. Automatically configures BUCK1 and BUCK2 to 3.3V.

Returns true if successful, false otherwise.

Reading Functions (Simplified)

uint16_t readVBAT()

Read battery voltage in millivolts (mV).

uint16_t readVBUS()

Read USB input voltage in millivolts (mV).

uint16_t readVSYS()

Read system voltage in millivolts (mV).

int16_t readCurrent()

Read battery current in milliamperes (mA). Positive value indicates charging, negative indicates discharging.

uint8_t readSOC()

Read battery State of Charge as a percentage (0-100%).

int8_t readTemp()

Read battery temperature in degrees Celsius.

Writing Functions (Simplified)

bool writeBuck1(float voltage)

Set BUCK1 output voltage. Valid range: 1.0V to 3.3V.

bool writeBuck2(float voltage)

Set BUCK2 output voltage. Valid range: 1.0V to 3.3V.

bool writeChargeCurrent(uint16_t mA)

Set charging current in milliamperes. Maximum: 992mA.

bool writeChargeVoltage(float voltage)

Set charge termination voltage.

Control Functions

bool enableBuck1()
bool enableBuck2()
bool disableBuck1()
bool disableBuck2()

Enable or disable BUCK converters.

bool enableCharger()
bool disableCharger()

Enable or disable battery charging.

GPIO Functions

bool setGpioMode(uint8_t pin, uint8_t mode)

Set GPIO mode (pin: 0-4). Available modes:

• NPM1300_GPIO_INPUT (0) - Input
• NPM1300_GPIO_OUT_LOGIC1 (8) - Output HIGH
• NPM1300_GPIO_OUT_LOGIC0 (9) - Output LOW
• NPM1300_GPIO_OUT_IRQ (5) - Interrupt output
• NPM1300_GPIO_EVENT_RISE (3) - Rising edge event
• NPM1300_GPIO_EVENT_FALL (4) - Falling edge event

bool setGpioOutput(uint8_t pin, bool state)

Set GPIO output HIGH or LOW.

bool getGpioInput(uint8_t pin)

Read GPIO input state.

bool setGpioPullUp(uint8_t pin, bool enable)
bool setGpioPullDown(uint8_t pin, bool enable)

Enable or disable pull-up/pull-down resistors.

Status Functions

bool isCharging()

Returns true if battery is currently charging.

bool isBatteryFull()

Returns true if battery is fully charged.

bool isConnected()

Check if nPM1300 is connected via I2C.

Examples

Basic Reading

#include <NPM1300.h>

NPM1300 pmic;

void setup() {
    Serial.begin(115200);
    pmic.begin();
}

void loop() {
    Serial.print("Voltage: ");
    Serial.print(pmic.readVBAT());
    Serial.println(" mV");
    
    Serial.print("Current: ");
    Serial.print(pmic.readCurrent());
    Serial.println(" mA");
    
    Serial.print("SOC: ");
    Serial.print(pmic.readSOC());
    Serial.println(" %");
    
    delay(2000);
}

BUCK Configuration

#include <NPM1300.h>

NPM1300 pmic;

void setup() {
    Serial.begin(115200);
    pmic.begin();
    
    // Set different voltages for BUCK1 and BUCK2
    pmic.writeBuck1(3.3);  // 3.3V for main system
    pmic.writeBuck2(1.8);  // 1.8V for sensors
    
    Serial.println("BUCK voltages configured");
}

void loop() {
    // Your code here
}

Charging Control

#include <NPM1300.h>

NPM1300 pmic;

void setup() {
    Serial.begin(115200);
    pmic.begin();
    
    // Configure charging
    pmic.writeChargeCurrent(100);   // 100mA charge current
    pmic.writeChargeVoltage(4.2);   // 4.2V termination voltage
    pmic.enableCharger();
    
    Serial.println("Charger configured");
}

void loop() {
    if (pmic.isCharging()) {
        Serial.println("Charging...");
    } else if (pmic.isBatteryFull()) {
        Serial.println("Battery full");
    } else {
        Serial.println("Not charging");
    }
    
    delay(1000);
}

GPIO Control

#include <NPM1300.h>

NPM1300 pmic;

void setup() {
    pmic.begin();
    
    // GPIO0 as output (LED)
    pmic.setGpioMode(0, NPM1300_GPIO_OUT_LOGIC0);
    
    // GPIO1 as input (Button) with pull-up
    pmic.setGpioMode(1, NPM1300_GPIO_INPUT);
    pmic.setGpioPullUp(1, true);
    
    // GPIO2 as interrupt output
    pmic.setGpioMode(2, NPM1300_GPIO_OUT_IRQ);
}

void loop() {
    // Read button
    bool buttonPressed = !pmic.getGpioInput(1);
    
    if (buttonPressed) {
        // Toggle LED
        static bool led = false;
        led = !led;
        pmic.setGpioOutput(0, led);
        delay(200);  // Debounce
    }
}

Advanced API

For users who prefer more descriptive function names, the library also provides:

• getVbatVoltage() instead of readVBAT()
• getBatCurrent() instead of readCurrent()
• getBatterySOC() instead of readSOC()
• setBuck1Voltage() instead of writeBuck1()
• setChargeCurrent() instead of writeChargeCurrent()

Both naming styles are fully supported.

Technical Notes

Register Addresses

The library uses 16-bit register addresses (Base Address + Offset) according to the nPM1300 datasheet:

BUCK Registers (Base: 0x0400)

• BUCK1ENASET: 0x0400
• BUCK1NORMVOUT: 0x0408
• BUCK2NORMVOUT: 0x040A
• BUCKSWCTRLSEL: 0x040F

Charger Registers (Base: 0x0300)

• BCHGENABLESET: 0x0304
• BCHGISETMSB: 0x0308
• BCHGVTERM: 0x030C
• BCHGCHARGESTATUS: 0x0334

ADC Registers (Base: 0x0500)

• TASK_VBAT_MEAS: 0x0500
• ADC_VBAT_MSB: 0x0511
• ADC_GP0_LSBS: 0x0515

Voltage Conversion

BUCK voltage range is 1.0V to 3.3V with 0.1V steps:

• Register value 0 = 1.0V
• Register value 23 = 3.3V
• Formula: Register Value = (Voltage - 1.0) / 0.1

Charge Current Configuration

Charging current range: 32 mA to 800 mA with 2 mA steps

• BCHGISETMSB = Current_mA / 2
• BCHGISETLSB = Current_mA % 2

Example: 100 mA → ISETMSB = 50, ISETLSB = 0

Charge Voltage Options

Termination voltage options (BCHGVTERM register):

• 3.50V, 3.55V, 3.60V, 3.65V
• 4.00V to 4.45V in 50mV steps

ADC Conversion

The nPM1300 uses a 10-bit ADC with different voltage ranges:

• VBAT: (ADC_value * 5000) / 1024 mV (0-5V range)
• VBUS: (ADC_value * 7500) / 1024 mV (0-7.5V range)
• VSYS: (ADC_value * 6375) / 1024 mV (0-6.375V range)

ADC conversion time: approximately 250 microseconds

Battery SOC

Note: The nPM1300 does not have built-in State of Charge calculation. The readSOC() function provides a simple voltage-based estimation. For accurate SOC measurement, use the Nordic nRF Connect SDK fuel gauge algorithm with the nPM1300.

I2C Communication

I2C address: 0x6B (7-bit)

Register access uses 16-bit addressing:

[Slave Address][High Byte][Low Byte][Data]
     0x6B         0x04        0x08     0x17

BUCK Control Sequence

To change BUCK voltage:

1. Write voltage value to BUCK1NORMVOUT/BUCK2NORMVOUT
2. Set BUCKSWCTRLSEL register to enable software control
3. The library handles this automatically in writeBuck1() and writeBuck2()

GPIO Configuration

The nPM1300 has 5 GPIO pins (GPIO0-GPIO4) that can be configured for various functions:

GPIO Modes:

• Input (with pull-up/pull-down)
• Output (logic high/low)
• Interrupt output
• Edge detection (rising/falling)
• BUCK control
• Load switch control

GPIO Register Base: 0x0600

Each GPIO has individual registers for:

• Mode (offset 0x00-0x04)
• Drive strength (offset 0x05-0x09)
• Pull-up enable (offset 0x0A-0x0E)
• Pull-down enable (offset 0x0F-0x13)
• Open drain (offset 0x14-0x18)
• Debounce (offset 0x19-0x1D)

GPIO status can be read from register 0x061E.

Compatibility

• Arduino Uno
• Arduino Nano
• Arduino Mega
• ESP32
• ESP8266
• nRF52 series
• Any Arduino-compatible board with I2C support

License

MIT License

Contributing

Contributions are welcome. Please open an issue or submit a pull request.

Support

For questions or issues, please open an issue on GitHub.

Changelog

Version 1.0.0

• Initial release
• BUCK1 and BUCK2 control
• Battery monitoring
• Charging control
• Simplified API