Multi-Function Device (MFD) with Charger, Fuel Gauge, and Regulators

Overview

This sample demonstrates how to use a multi-function power management device (MFD) with Zephyr’s driver subsystems. The sample is designed to work with any MFD that provides charger, fuel gauge, and regulator functionality through the standard Zephyr driver interfaces.

The sample shows how to:

Initialize and configure an MFD (Multi-Function Device) driver
Monitor battery charging status and health using the Charger API
Read battery voltage, state of charge, and cycle count using the Fuel Gauge API
Control and monitor voltage regulators using the Regulator API
Handle interrupts, power-good signals, and reset signals from the device

The application continuously polls the charger and fuel gauge to display real-time battery and charging information, including:

Charger configuration (current limits, charge currents, voltages)
Charging status (online, present, charging state, health)
Battery fuel gauge data (voltage, state of charge, cycle count)
Regulator output voltages

Requirements

The sample requires a board with an MFD device that supports charger, fuel gauge, and regulator functionality. The MFD device must be defined in the devicetree with appropriate labels so that the sample code can access the individual subsystems.

The devicetree must include:

A node with the label charger for the charger interface
A node with the label fuelgauge for the fuel gauge interface
A node with the label buck for the buck regulator (or similar)
A node with the label buckboost for the buck-boost regulator (or similar)

An example MFD device overlay is provided showing how to configure these labels for a specific board and MFD chip. Refer to the overlay file for your board to understand how to adapt it for other MFD devices.

Hardware Setup

The specific hardware connections depend on the MFD device being used. Refer to the device datasheet and the overlay file for your board for detailed connection instructions.

At minimum, the MFD requires:

A communications bus
Power supply
A battery connected to the charger and fuel gauge subsystems for proper operation

Building and Running

The code can be found in samples/drivers/mfd_charger.

To build and flash the application for your board:

west build -b <board> samples/drivers/mfd_charger
west flash

Replace <board> with your target board name.

If your board does not have an MFD overlay, you will need to create one. Create a file in the boards/ subdirectory named <board>.overlay with the appropriate devicetree configuration for your MFD device. See the board-specific documentation for examples.

Sample Output

The sample output will vary based on the specific MFD device and configuration. A typical output showing battery charging and monitoring information might look like:

[0:00:00.003]: Found device "charger", getting charger data
[0:00:00.006]: Current (Fast Charge): 20000 uA
[0:00:00.009]: Input Regulation Voltage: 3800000 uV
[0:00:00.012]: Current (Termination): 5000 uA
[0:00:03.021]: Fuel gauge Battery Capacity: 1000
[0:00:03.024]: Buck Output Voltage: 1300000
[0:00:03.027]: Buck Boost Output Voltage: 3300000
[0:00:03.030]: Online: Charger is active.
[0:00:03.033]: Present: Battery is Present.
[0:00:03.036]: Status: Charger is Charging.
[0:00:03.039]: Mode: Charger is in Fast Mode (CC).
[0:00:03.042]: Health: Battery is Cool.
[0:00:03.045]: Fuel gauge Voltage: 3950000
[0:00:03.048]: Fuel gauge Status 0x0
[0:00:03.051]: Fuel gauge SoC: 75

Note

The values shown above will vary depending on the actual MFD device used, the battery state of charge, and the device configuration.