diff --git a/internal_filesystem/lib/drivers/fri3d/device.py b/internal_filesystem/lib/drivers/fri3d/device.py
new file mode 100644
index 00000000..84f5c76f
--- /dev/null
+++ b/internal_filesystem/lib/drivers/fri3d/device.py
@@ -0,0 +1,26 @@
+import struct
+
+from micropython import const
+from machine import I2C
+
+# common registers
+_REG_VERSION = const(0x00)
+
+
+class Device:
+    """Fri3d I2C device."""
+
+    def __init__(self, i2c_bus: I2C, address: int):
+        """Read from a sensor on the given I2C bus, at the given address."""
+        self.i2c = i2c_bus
+        self.address = address
+
+    def _read(self, format, reg, amount):
+        return struct.unpack(format, self.i2c.readfrom_mem(self.address, reg, amount))
+
+    def _write(self, reg, value):
+        self.i2c.writeto_mem(self.address, reg, value, addrsize=8)
+
+    @property
+    def version(self) -> tuple[int, int, int]:
+        return self._read("BBB", _REG_VERSION, 3)
diff --git a/internal_filesystem/lib/drivers/fri3d/expander.py b/internal_filesystem/lib/drivers/fri3d/expander.py
new file mode 100644
index 00000000..c24cbe6f
--- /dev/null
+++ b/internal_filesystem/lib/drivers/fri3d/expander.py
@@ -0,0 +1,89 @@
+import struct
+
+from micropython import const
+from machine import I2C, Pin
+
+from .device import Device
+
+# registers
+_EXPANDER_REG_INPUTS = const(0x04)
+_EXPANDER_REG_ANALOG = const(0x06)
+_EXPANDER_REG_LCD_BRIGHTNESS = const(0x12)
+_EXPANDER_REG_DEBUG_LED = const(0x14)
+_EXPANDER_REG_CONFIG = const(0x16)
+
+_EXPANDER_I2CADDR_DEFAULT = const(0x50)
+
+
+class Expander(Device):
+    """Fri3d Badge 2026 expander MCU."""
+
+    def __init__(
+        self,
+        i2c_bus: I2C,
+        address: int = _EXPANDER_I2CADDR_DEFAULT,
+        int_pin: Pin = None,
+    ):
+        """Read from a sensor on the given I2C bus, at the given address."""
+        Device.__init__(self, i2c_bus, address)
+        self.use_interrupt = False
+        if int_pin:
+            self.use_interrupt = True
+            self._rx_buf = bytearray(2)
+            self._rx_mv = memoryview(self._rx_buf)
+            self.int_pin = int_pin
+            self.i2c.readfrom_mem_into(self.address, _EXPANDER_REG_INPUTS, self._rx_mv)
+            self.int_pin.irq(trigger=Pin.IRQ_RISING, handler=self.int_callback)
+
+    def int_callback(self, p):
+        self.i2c.readfrom_mem_into(self.address, _EXPANDER_REG_INPUTS, self._rx_mv)
+
+    @property
+    def analog(self) -> tuple[int, int, int, int, int, int]:
+        """Read the analog inputs: ain1, ain0, battery_monitor, usb_monitor, joystick_y, joystick_x"""
+        return self._read("<HHHHHH", _EXPANDER_REG_ANALOG, 12)
+
+    @property
+    def digital(
+        self,
+    ) -> tuple[bool, bool, bool, bool, bool, bool, bool, bool, bool, bool, bool, bool]:
+        """Read the digital inputs: usb_plugged, joy_right, joy_left, joy_down, joy_up, button_menu, button_b, button_a, button_y, button_x, charger_standby, charger_charging"""
+        if self.use_interrupt:
+            inputs = struct.unpack("<H", self._rx_buf)[0]
+        else:
+            inputs = self._read("<H", _EXPANDER_REG_INPUTS, 2)[0]
+        return tuple([bool(int(digit)) for digit in "{:016b}".format(inputs)[4:]])
+
+    @property
+    def lcd_brightness(self) -> int:
+        """Read the LCD brightness state (0-100)"""
+        return self._read("<H", _EXPANDER_REG_LCD_BRIGHTNESS, 2)[0]
+
+    @lcd_brightness.setter
+    def lcd_brightness(self, value: int):
+        """Set the LCD brightness (0-100)"""
+        if value >= 0 and value <= 100:
+            self._write(_EXPANDER_REG_LCD_BRIGHTNESS, struct.pack("<H", value))
+
+    @property
+    def debug_led(self) -> int:
+        """Read the Debug LED state (0-100)"""
+        return self._read("<H", _EXPANDER_REG_DEBUG_LED, 2)[0]
+
+    @debug_led.setter
+    def debug_led(self, value: int):
+        """Set the Debug LED (0-100)"""
+        if value >= 0 and value <= 100:
+            self._write(_EXPANDER_REG_DEBUG_LED, struct.pack("<H", value))
+
+    @property
+    def config(self) -> tuple[bool, bool, bool]:
+        """Read the configuration bits: reboot, lcd_reset, aux_power"""
+        config = self._read("B", _EXPANDER_REG_CONFIG, 1)[0]
+        return tuple([bool(int(digit)) for digit in "{:08b}".format(config)[5:]])
+
+    @config.setter
+    def config(self, value: int):
+        """set the configuration byte"""
+        if value >= 0 and value <= 0xFF:
+            self._write(_EXPANDER_REG_CONFIG, struct.pack("B", value))