CardCharge

A minimal charging and battery-monitor firmware for the M5Stack Cardputer & M5Stack Cardputer ADV.

CardputerCharge provides a clean battery status screen while the device is connected to USB power. It shows the current battery percentage and voltage, supports adjustable display brightness, and allows the display to be turned off while charging.

Features

• Large battery indicator
• Battery percentage
• Battery voltage
• Battery color based on charge level
• Display on/off toggle
• Adjustable display brightness
• Wi-Fi disabled
• Bluetooth disabled
• Speaker and microphone disabled
• Designed specifically for the M5Stack Cardputer

Screenshot

Controls

Key	Action
↑/,	Increase display brightness
↓/.	Decrease display brightness
Any other key	Toggle display on/off

Charging

Connect the Cardputer ADV through USB-C.

The Cardputer's power switch must be set to ON for the internal battery to charge.

CardputerCharge displays the battery voltage and estimated battery percentage while charging.

The Cardputer ADV does not expose a reliable charging-current or charging-state signal, so the firmware does not attempt to display an explicit charging status.

Battery Display

The battery indicator changes color according to the current battery level.

Approximate behavior:

Low Full

Red → Orange → Yellow → Green

The displayed voltage is refreshed periodically without continuously redrawing the screen.

Power Saving

Since this firmware is intended primarily for charging and battery monitoring, unused hardware is disabled:

• Wi-Fi
• Bluetooth
• Speaker
• Microphone

The display backlight can also be turned off while the firmware continues running.

Prebuilt binaries

• CardCharge-vX-firmware.bin = application only
• CardCharge-vX-full.bin = bootloader + partitions + application

Contribution

Pull requests are very welcome.

License

MIT License. See LICENSE for details.

Made with ❤️ by Dante Wackermann.