nanoFramework.Iot.Device.M5Pm1 1.0.6

M5PM1 - M5Stack power-management IC

The M5PM1 is M5Stack's ESP32-S3-era power-management IC, used on boards such as the M5StickS3. It handles the battery and USB power paths, charging control and status, board power gates and external 5V switching.

This binding covers the I2C control plane and exposes the telemetry and control features that are most commonly used: battery / VBUS / 5V-out voltage, external 5V enable, charge enable, charging status and the active power source. The register behaviour is ported from the M5Stack M5Unified power implementation, which is the most authoritative reference for the M5PM1 (M5Stack's public product docs do not expose a full register map).

Documentation

• M5StickS3 product page
• M5Stack I2C device address table
• M5Unified power implementation (Power_Class.cpp)
• M5Unified power API (Power_Class.hpp)
• M5GFX board autodetect / PM1 checks (M5GFX.cpp)

Device family

Usage

Important: on the M5StickS3 the M5PM1 is on the internal I2C bus (SDA = GPIO47, SCL = GPIO48). Configure those pins before creating the I2cDevice.

using Iot.Device.M5Pm1;
using nanoFramework.Hardware.Esp32;
using System.Device.I2c;
using System.Diagnostics;
using UnitsNet;

// M5StickS3 internal I2C bus.
Configuration.SetPinFunction(47, DeviceFunction.I2C1_DATA);
Configuration.SetPinFunction(48, DeviceFunction.I2C1_CLOCK);

// The M5PM1 is a 100 kHz (standard-mode) device; the ESP32 default of 400 kHz is NAK'd.
I2cConnectionSettings settings = new I2cConnectionSettings(1, M5Pm1.I2cDefaultAddress, I2cBusSpeed.StandardMode);
I2cDevice i2cDevice = new I2cDevice(settings);

M5Pm1 power = new M5Pm1(i2cDevice);

// The constructor wakes the PMIC and applies the M5Stack reliability init (disable the I2C idle-sleep
// and the watchdog); the M5PM1 sleeps on an idle I2C bus. Optionally confirm the device ID.
int deviceId = power.GetDeviceId(); // should equal M5Pm1.DeviceId (0x2050)
Debug.WriteLine($"M5PM1 device ID: 0x{deviceId:X4} (expected 0x{M5Pm1.DeviceId:X4}).");

// Control.
power.BatteryChargeEnabled = true;
power.ExternalOutputEnabled = true;

// Telemetry (UnitsNet ElectricPotential).
Debug.WriteLine($"Battery : {power.GetBatteryVoltage().Millivolts} mV");
Debug.WriteLine($"VBUS    : {power.GetVbusVoltage().Millivolts} mV");
Debug.WriteLine($"5V out  : {power.GetOutputVoltage().Millivolts} mV");
Debug.WriteLine($"Source  : {power.GetPowerSource()}");
Debug.WriteLine($"Charging: {power.IsCharging}");

GPIO

The M5PM1 exposes five general-purpose I/O pins (Pin.Gpio0 to Pin.Gpio4). Each pin has a mux function (GpioFunction), a direction (the standard PinMode input or output only), an output driver type (GpioDrive), an output latch and an input reading. Boards wire these pins to different loads (for example the M5StickS3 uses Gpio2 for the L3B / LCD power gate).

using System.Device.Gpio;

// Drive GPIO2 high as a push-pull output (e.g. the M5StickS3 L3B / LCD power gate).
power.SetGpioFunction(Pin.Gpio2, GpioFunction.Gpio);
power.SetGpioDrive(Pin.Gpio2, GpioDrive.PushPull);
power.SetGpioMode(Pin.Gpio2, PinMode.Output);
power.WriteGpio(Pin.Gpio2, PinValue.High);

// Read GPIO0 as an input (e.g. the M5StickS3 charge-status line).
power.SetGpioMode(Pin.Gpio0, PinMode.Input);
PinValue level = power.ReadGpio(Pin.Gpio0);