👁 Image
nanoFramework.Iot.Device.Axp2101 1.0.3

AXP2101 - Enhanced Single Cell Li-Battery and Power System Management IC

Summary

The AXP2101 is an advanced power management IC (PMIC) manufactured by X-Powers, widely used in embedded devices such as the M5Stack CoreS3 (ESP32-S3-based). It provides comprehensive power management with multiple configurable voltage regulators, battery charging control, ADC measurements, fuel gauge, watchdog, and interrupt handling. It communicates over I2C at default address 0x34.

Documentation

• AXP2101 Datasheet (PDF)
• M5Stack CoreS3 Documentation
• CoreS3 Schematics (PDF)
• XPowersLib (lewisxhe) - Reference C++ implementation
• Related nanoFramework binding:

Device Capabilities

Voltage Ranges

Usage

// Configure I2C pins for ESP32-S3 (M5Stack CoreS3)
Configuration.SetPinFunction(12, DeviceFunction.I2C1_DATA);
Configuration.SetPinFunction(11, DeviceFunction.I2C1_CLOCK);

I2cDevice i2cAxp2101 = new(new I2cConnectionSettings(1, Axp2101.I2cDefaultAddress));
Axp2101 power = new Axp2101(i2cAxp2101);

Important: make sure you read the documentation of your battery and set up the proper charging values and stop current. Overcharging your battery may damage it.

Setting up power rails

Configure DCDC and LDO voltage rails for your board. Example for M5Stack CoreS3:

// DCDC1: ESP32-S3 core — 3.3V (do NOT disable this!)
power.DcDc1Voltage = ElectricPotential.FromVolts(3.3);
power.EnableDcDc1();

// ALDO1: System peripherals — 1.8V
power.Aldo1Voltage = ElectricPotential.FromVolts(1.8);
power.EnableAldo1();

// ALDO2: Display/LCD — 3.3V
power.Aldo2Voltage = ElectricPotential.FromVolts(3.3);
power.EnableAldo2();

Warning: Never disable DCDC1 on a CoreS3 as it powers the ESP32-S3 core. Disabling it will brick the system until the next power cycle.

Battery charging

power.EnableCellBatteryCharge();
power.SetChargeConstantCurrent(ChargingCurrent.Current200mA);
power.SetChargeTargetVoltage(ChargeTargetVoltage.Voltage4V2);
power.SetPrechargeCurrent(PrechargeCurrent.Current25mA);
power.SetChargeTerminationCurrent(ChargeTerminationCurrent.Current25mA);
power.EnableChargeTerminationLimit();
power.SetThermalThreshold(ThermalThreshold.Temperature100C);

Battery status

int percentage = power.GetBatteryPercentage();
ElectricPotential batteryVoltage = power.GetBatteryVoltage();
ChargingStatus chargeStatus = power.GetChargerStatus();
bool batteryConnected = power.IsBatteryConnected;

Debug.WriteLine($"Battery: {percentage}%, {batteryVoltage.Volts:F2}V, {chargeStatus}");
Debug.WriteLine($" Connected: {batteryConnected}");

VBUS monitoring

if (power.IsVbusGood)
{
 ElectricPotential vbusVoltage = power.GetVbusVoltage();
 Debug.WriteLine($"VBUS: {vbusVoltage.Volts:F2}V, Connected");
}

Using the power button

The power key supports short and long press detection via interrupts:

power.EnableIrq(Axp2101Irq.PowerKeyShortPress | Axp2101Irq.PowerKeyLongPress);
power.SetPowerKeyPressOnTime(0); // 128 ms
power.SetPowerKeyPressOffTime(0); // 4 s
power.EnableLongPressShutdown();
power.ClearIrqStatus();

// In your main loop:
if (power.IsPowerKeyShortPressIrq())
{
 Debug.WriteLine("Short press");
}

if (power.IsPowerKeyLongPressIrq())
{
 Debug.WriteLine("Long press");
}

power.ClearIrqStatus();

Temperature and ADC

Enable ADC channels and read measurements:

power.EnableBatteryVoltageMeasure();
power.EnableVbusVoltageMeasure();
power.EnableSystemVoltageMeasure();
power.EnableTemperatureMeasure();

Debug.WriteLine($"Die Temperature: {power.GetInternalTemperature().DegreesCelsius:F1} °C");
Debug.WriteLine($"System Voltage : {power.GetSystemVoltage().Volts:F2} V");

Watchdog

power.SetWatchdogConfig(WatchdogConfig.IrqAndReset);
power.SetWatchdogTimeout(WatchdogTimeout.Timeout8s);
power.EnableWatchdog();

// Feed the watchdog periodically:
power.ClearWatchdog();

Advanced features

The AXP2101 supports many additional features including VBUS input limits, backup battery charging, fast power-on sequencing, fuel gauge ROM programming, sleep/wakeup, and DCDC forced-PWM mode. You can check out the to get more details on how to use these features.

Note: this binding uses UnitsNet for units like Voltage and Temperature.

M5Stack CoreS3 Power Rail Mapping

Differences from AXP192

If migrating from the binding, note these key differences: