diff --git a/.github/workflows/python-linter.yml b/.github/workflows/python-linter.yml
index a372aec..7a5ea9a 100644
--- a/.github/workflows/python-linter.yml
+++ b/.github/workflows/python-linter.yml
@@ -34,5 +34,5 @@ jobs:
 
     - name: '😾 Lint with flake8'
       run: |
-        flake8 --count --ignore=C901 --select=E9,F63,F7,F82 --exclude=manifest.py --show-source --statistics lib/
-        flake8 --count --ignore=C901 --max-complexity=15 --max-line-length=120 --exclude=manifest.py --statistics lib/
+        flake8 --count --ignore=C901,E221,E203 --select=E9,F63,F7,F82 --exclude=manifest.py --show-source --statistics lib/
+        flake8 --count --ignore=C901,E221,E203 --max-complexity=15 --max-line-length=120 --exclude=manifest.py --statistics lib/
diff --git a/lib/opta/example.py b/lib/opta/example.py
new file mode 100644
index 0000000..e4bfae5
--- /dev/null
+++ b/lib/opta/example.py
@@ -0,0 +1,91 @@
+# This file is part of the blueprint package.
+# Copyright (c) 2024 Arduino SA
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at https://mozilla.org/MPL/2.0/.
+import opta
+import logging
+
+
+if __name__ == "__main__":
+    logging.basicConfig(
+        datefmt="%H:%M:%S",
+        format="%(asctime)s.%(msecs)03d %(message)s",
+        level=logging.INFO  # Switch to DEBUG to see raw commands
+    )
+
+    opta = opta.Opta(bus_id=3)
+
+    # enum_devices initializes the bus, resets all expansions, and returns a list of
+    # detected expansions. NOTE: keep a reference to the list of expansion for later
+    # use, as every time this function is called it restarts the enumeration process.
+    for e in opta.enum_devices():
+        print("")
+        logging.info(f"Expansion type: {e.type} address: 0x{e.addr:02X} name: {e.name}")
+
+        # Read firmware version.
+        major, minor, patch = e.firmware_version()
+        logging.info(f"Firmware Version Major: {major} Minor: {minor} Patch: {patch}")
+
+        # Read product ID.
+        pid = e.product_id()
+        logging.info("Product ID bytes: " + ", ".join(["0x%02X" % a for a in pid[0:8]]))
+
+        if e.type == "digital":
+            # Write digital pins. If the default state and timeout (in milliseconds) are
+            # also specified, the pins will revert to the specified default state after
+            # the timeout expires.
+            e.digital(pins=0b10101010, default=0b01010101, timeout=3000)
+
+            # If no args are specified, digital() returns all digital pins.
+            pins = e.digital()
+            logging.info(f"Digital pins: 0b{pins:08b}")
+
+            # Read analog pins.
+            logging.info("Analog pin  [0   ]: %d" % e.analog(channel=0))
+            logging.info("Analog pins [0..7]: " + str(e.analog()))
+
+        if e.type == "analog":
+            # Configure LEDs on Opta Analog
+            e.digital(pins=0b10011001)
+
+            # Configure analog channels. Note almost all of the possible args are used here
+            # for demonstration purposes, however only a few are actually required (such as
+            # the channel type and mode). Most of the other args have reasonable defaults.
+
+            # Configure channel (0) as PWM.
+            e.analog(channel=0, channel_type="pwm", period=1000, duty=50, default_period=500)
+
+            # Configure channel (2) as DAC.
+            e.analog(channel=2, channel_type="dac", channel_mode="voltage", value=7540)
+
+            # Configure channel (3) as ADC.
+            e.analog(channel=3, channel_type="adc", channel_mode="voltage", pulldown=True,
+                     rejection=False, diagnostic=False, average=0, secondary=False)
+
+            # Configure channel (4) as RTD.
+            e.analog(channel=4, channel_type="rtd", use_3_wire=False, current_ma=1.2, update_time=0)
+
+            # Configure channel (5) as digital input.
+            e.analog(channel=5, channel_type="din", comparator=True, inverted=False, filtered=True,
+                     scale=False, sink=1, threshold=9, debounce_mode="simple", debounce_time=24)
+
+            # Read ADC channel (3).
+            # This should print 65535 if channels 2 and 3 are connected.
+            logging.info("ADC channel  [3   ]: %d" % e.analog(channel=3))
+
+            # Read all analog channels.
+            logging.info("Analog channels [0..7]: " + str(e.analog()))
+
+            # Read RTD channel (4).
+            logging.info("RTD channel  [4   ]: %.1f ohm" % e.analog(channel=4))
+
+            # Read DIN channel (5).
+            logging.info("DIN channel  [5   ]: %d" % e.analog(channel=5))
+
+            # Read all analog channels.
+            logging.info("Analog channels [0..7]: " + str(e.analog()))
+
+            # Re-configure channel (2) as DAC.
+            e.analog(channel=2, channel_type="dac", channel_mode="voltage", value=3770)
+            logging.info("ADC channel  [3   ]: %d" % e.analog(channel=3))
diff --git a/lib/opta/manifest.py b/lib/opta/manifest.py
new file mode 100644
index 0000000..cd8384e
--- /dev/null
+++ b/lib/opta/manifest.py
@@ -0,0 +1,6 @@
+metadata(
+    description="Modules for Arduino Opta.",
+    version="0.0.1",
+)
+
+module("opta.py")
diff --git a/lib/opta/opta.py b/lib/opta/opta.py
new file mode 100644
index 0000000..29dc8ab
--- /dev/null
+++ b/lib/opta/opta.py
@@ -0,0 +1,444 @@
+# This file is part of the blueprint package.
+# Copyright (c) 2024 Arduino SA
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at https://mozilla.org/MPL/2.0/.
+import struct
+import logging
+from time import sleep_ms
+from machine import I2C
+from machine import Pin
+from micropython import const
+
+_MIN_ADDRESS = const(0x0B)
+_TMP_ADDRESS = const(0x0A)
+_MAX_ADDRESS = const(0x0B + 0x0A)
+
+# Header and CRC length.
+_CMD_HDR_LEN = const(0x03)
+_CMD_CRC_LEN = const(0x01)
+
+# Command direction (SET == 1, GET == 2)
+_CMD_DIR_SET = const(0x01)
+_CMD_DIR_GET = const(0x02)
+
+# Commands are encoded as follows:
+# [direction, command opcode, response length, ack required]
+_CMD_CHIP_RESET         = const((_CMD_DIR_SET, 0x01, 0, False))
+_CMD_SET_ADDRESS        = const((_CMD_DIR_SET, 0x02, 0, False))
+_CMD_GET_ADDRESS        = const((_CMD_DIR_GET, 0x03, 2, False))
+
+# Misc commands such as product ID, firmware etc...
+_CMD_GET_PRODUCT_ID     = const((_CMD_DIR_GET, 0x25, 33, False))
+_CMD_GET_FW_VERSION     = const((_CMD_DIR_GET, 0x16, 3, False))
+_CMD_SET_BOOTLOADER     = const((_CMD_DIR_SET, 0xF3, 0, False))
+
+# Flash commands.
+_CMD_SET_FLASH_WRITE    = const((_CMD_DIR_SET, 0x17, 0, False))
+_CMD_GET_FLASH_READ     = const((_CMD_DIR_GET, 0x18, 32, False))
+
+# Digital pins commands.
+_CMD_SET_DIGITAL_PIN    = const((_CMD_DIR_SET, 0x06, 0, False))
+_CMD_GET_DIGITAL_BUS    = const((_CMD_DIR_GET, 0x04, 2, False))
+_CMD_SET_DIGITAL_DEF    = const((_CMD_DIR_SET, 0x08, 0, False))
+_CMD_SET_DIGITAL_BUS_OA = const((_CMD_DIR_SET, 0x15, 0, True))
+
+# Analog channels commands.
+_CMD_CFG_ANALOG_ADC     = const((_CMD_DIR_SET, 0x09, 0, True))
+_CMD_CFG_ANALOG_DIN     = const((_CMD_DIR_SET, 0x11, 0, True))
+_CMD_CFG_ANALOG_PWM     = const((_CMD_DIR_SET, 0x13, 0, True))
+_CMD_CFG_ANALOG_DAC     = const((_CMD_DIR_SET, 0x0C, 0, True))
+_CMD_CFG_ANALOG_RTD     = const((_CMD_DIR_SET, 0x0E, 0, True))
+_CMD_CFG_ANALOG_HIZ     = const((_CMD_DIR_SET, 0x24, 0, True))
+_CMD_SET_ANALOG_DAC     = const((_CMD_DIR_SET, 0x0D, 0, True))
+_CMD_SET_ANALOG_RTD_TIM = const((_CMD_DIR_SET, 0x10, 0, True))
+
+# Read analog channels (Analog pin, ADC, RTD, Digital In)
+_CMD_GET_ANALOG_PIN     = const((_CMD_DIR_GET, 0x05, 2, False))
+_CMD_GET_ANALOG_PIN_ALL = const((_CMD_DIR_GET, 0x07, 32, False))
+_CMD_GET_ANALOG_ADC     = const((_CMD_DIR_GET, 0x0A, 3, False))
+_CMD_GET_ANALOG_ADC_ALL = const((_CMD_DIR_GET, 0x0B, 16, False))
+_CMD_GET_ANALOG_RTD     = const((_CMD_DIR_GET, 0x0F, 5, False))
+_CMD_GET_ANALOG_DIN     = const((_CMD_DIR_GET, 0x12, 1, False))
+
+# Default analog channels values and timeout.
+_CMD_SET_ANALOG_PWM_DEF = const((_CMD_DIR_SET, 0x33, 0, True))
+_CMD_SET_ANALOG_DAC_DEF = const((_CMD_DIR_SET, 0x3D, 0, True))
+_CMD_SET_ANALOG_TIMEOUT = const((_CMD_DIR_SET, 0x31, 0, True))
+
+_CHANNEL_MODES = const((None, "voltage", "current"))
+_CHANNEL_TYPES = const(("adc", "dac", "rtd", "pwm", "hiz", "din"))
+
+
+class Expansion:
+    def __init__(self, opta, type, addr, name):
+        self.opta = opta
+        self.type = type
+        self.addr = addr
+        self.name = name
+        self.channels = {}
+
+    def product_id(self):
+        """
+        Returns the product ID bytes of the expansion.
+        """
+        return self.opta._cmd(self.addr, _CMD_GET_PRODUCT_ID)
+
+    def firmware_version(self):
+        """
+        Returns the firmware version of the expansion.
+        """
+        return self.opta._cmd(self.addr, _CMD_GET_FW_VERSION)
+
+    def _flash(self, address, size=0, data=None):
+        """
+        Reads from or writes to the flash memory at the specified address.
+
+        NOTE: This should be used for production purposes only!
+
+        Parameters:
+            - address : The memory address to read from or write to.
+            - size : Number of bytes to read from the flash memory.
+            - data : Bytes to write to the flash memory.
+
+        Returns:
+            Data read from the flash memory as bytes, if reading. Returns None if writing.
+        """
+        size = size if data is None else len(data)
+        if size < 0 or size > 32:
+            raise RuntimeError("Maximum flash read/write size is 32")
+        if data is None:
+            resp = self.opta._cmd(self.addr, _CMD_GET_FLASH_READ, "<HB", address, size)
+            return struct.unpack("<HB32s", resp)[-1][0:size]
+        self.opta._cmd(self.addr, _CMD_SET_FLASH_WRITE, f"<HB{size}s", address, size, data)
+
+    def digital(self, pins=None, timeout=None, default=0):
+        """
+        Reads or writes digital pins.
+
+        Parameters:
+            - pins : Digital pins mask to set. If None, returns the state of all pins.
+            - timeout : The timeout in milliseconds, after which pins revert to the default state.
+            - default : The default state to which the pins will revert to after the timeout expires.
+
+        Note:
+            - For Opta Analog, this functions supports writing digital LEDs only.
+
+        Returns: The current state of the digital pins if reading, or None if setting the pins.
+        """
+        if self.type == "analog":
+            if pins is None:
+                raise RuntimeError("Function is not supported on analog expansions")
+            return self.opta._cmd(self.addr, _CMD_SET_DIGITAL_BUS_OA, "B", pins)
+        if pins is None and timeout is None:
+            return struct.unpack("<H", self.opta._cmd(self.addr, _CMD_GET_DIGITAL_BUS))[0]
+        if pins is not None:
+            self.opta._cmd(self.addr, _CMD_SET_DIGITAL_PIN, "B", pins)
+        if timeout is not None:
+            return self.opta._cmd(self.addr, _CMD_SET_DIGITAL_DEF, "<BH", default, timeout)
+
+    def analog(self, channel=None, channel_type=None, channel_mode=None, timeout=None, **kwargs):
+        """
+        Configures or reads analog channels.
+
+        Parameters:
+            - timeout : Set timeout in milliseconds after which analog channels revert to their default
+                        states set previously with analog(). Note if this is set, all other args are ignored.
+            - channel : The channel number to configure, read, or write. If None, reads all ADC channels.
+            - channel_type : Channel type can be "adc", "dac", "pwm", "rtd", "hiz", "din".
+            - channel_mode : "voltage" or "current" (default="voltage" for ADC channels).
+
+        kwargs :
+            hiz configuration:
+            - no args.
+
+            adc configuration:
+            - average : Number of points for moving average (0-255, default=0).
+            - rejection : Enable rejection (default=False).
+            - diagnostic : Enable diagnostic (default=False).
+            - pulldown : Enable pulldown (default=True for voltage, False for current).
+            - secondary : This ADC channel is shared with another function (default=False).
+
+            dac configuration:
+            - use_slew : Enable slew rate control (default=False).
+            - slew_rate : Slew rate if `use_slew` is True (default=0).
+            - limit_current : Limit current (default=False).
+            - value : Value to write to a DAC channel.
+            - default_value: The default value to revert to, after the timeout set with timeout() expires.
+
+            pwm configuration:
+            - period: PWM period in uS (for example 1000uS).
+            - duty:  high duty cycle in % (for example 50%).
+            - default_period: The default value to revert to, after the timeout set with timeout() expires.
+            - default_duty: The default value to revert to, after the timeout set with timeout() expires.
+
+            rtd configuration:
+            - use_3_wire: 3-Wire RTD (default = False).
+            - current_ma: RTD current in mA (default = 1.2mA).
+            - update_time: The update time of all RDT channels.
+
+            din (digital input) configuration:
+            - comparator : Enable comparator (default=True).
+            - filtered : Select the filtered input to the comparator (default=True).
+            - inverted : Invert the output from the digital input comparator (default=False).
+            - scale : Comparator voltage scale (default=False).
+            - threshold : Comparator voltage threshold (default 9).
+            - sink : Sets the sink current in digital input logic mode (0-31, default 1)
+            - debounce_mode : Debounce mode ("simple", "integrator" or None to disable debounce, default="simple")
+            - debounce_time : Debounce time (0-31, default 24)
+
+        Returns: ADC value(s) if reading, or None if configuring a channel or setting the analog timeout.
+        """
+        if channel is not None:
+            if self.type == "analog" and (channel < 0 or channel > 7):
+                raise ValueError("Invalid channel specified")
+            if self.type == "digital" and (channel < 0 or channel > 16):
+                raise ValueError("Invalid channel specified")
+
+        # Set default analog channels timeout.
+        if timeout is not None:
+            if self.type != "analog":
+                raise RuntimeError("Function is not supported on digital expansions")
+            return self.opta._cmd(self.addr, _CMD_SET_ANALOG_TIMEOUT, "<H", timeout)
+
+        # Read a all analog channels.
+        if channel is None:
+            fmt = "<HHHHHHHH" if self.type == "analog" else "<HHHHHHHHHHHHHHHH"
+            cmd = _CMD_GET_ANALOG_ADC_ALL if self.type == "analog" else _CMD_GET_ANALOG_PIN_ALL
+            return struct.unpack(fmt, self.opta._cmd(self.addr, cmd))
+
+        # Read a single analog channel.
+        if channel_type is None:
+            channel_type = self.channels.get(channel, None)
+            if self.type == "digital":
+                return struct.unpack("<H", self.opta._cmd(self.addr, _CMD_GET_ANALOG_PIN, "B", channel))[-1]
+            elif channel_type == "rtd":
+                return struct.unpack("<Bf", self.opta._cmd(self.addr, _CMD_GET_ANALOG_RTD, "B", channel))[-1]
+            elif channel_type == "adc":
+                return struct.unpack("<BH", self.opta._cmd(self.addr, _CMD_GET_ANALOG_ADC, "B", channel))[-1]
+            elif channel_type == "din":
+                return (struct.unpack("B", self.opta._cmd(self.addr, _CMD_GET_ANALOG_DIN))[-1] & channel) == channel
+            else:
+                raise RuntimeError("Channel is not configured or not readable")
+
+        # Configure a new channel
+        if channel_type not in _CHANNEL_TYPES:
+            raise ValueError("Invalid channel type.")
+        if channel_mode not in _CHANNEL_MODES:
+            raise ValueError("Invalid channel mode.")
+
+        def get_bool(k, d):
+            # True is 1 and False is 2.
+            return 1 if kwargs.get(k, d) else 2
+
+        if channel_type == "hiz":
+            self.opta._cmd(self.addr, _CMD_CFG_ANALOG_HIZ, "<B", channel)
+        elif channel_type == "rtd":
+            self.opta._cmd(
+                self.addr,
+                _CMD_CFG_ANALOG_RTD,
+                "<BBf",
+                channel,
+                get_bool("use_3_wire", False),
+                kwargs.get("current_ma", 1.2),
+            )
+            self.opta._cmd(self.addr, _CMD_SET_ANALOG_RTD_TIM, "<H", kwargs.get("update_time", 800))
+        elif channel_type == "adc":
+            self.opta._cmd(
+                self.addr,
+                _CMD_CFG_ANALOG_ADC,
+                "BBBBBBB",
+                channel,
+                channel_mode == "current",
+                get_bool("pulldown", channel_mode == "voltage"),
+                get_bool("rejection", False),
+                get_bool("diagnostic", False),
+                kwargs.get("average", 0),
+                get_bool("secondary", False),
+            )
+        elif channel_type == "dac":
+            if "value" not in kwargs:
+                raise ValueError("DAC requires a value argument")
+            # Configure DAC channel and update the output value.
+            self.opta._cmd(
+                self.addr,
+                _CMD_CFG_ANALOG_DAC,
+                "BBBBB",
+                channel,
+                channel_mode == "current",
+                get_bool("limit_current", channel_mode == "voltage"),
+                get_bool("slew_rate", False),
+                kwargs.get("slew_rate", 0),
+            )
+            self.opta._cmd(self.addr, _CMD_SET_ANALOG_DAC, "<BHB", channel, kwargs["value"], 1)
+            if "default_value" in kwargs:
+                value = kwargs["default_value"]
+                self.opta._cmd(self.addr, _CMD_SET_ANALOG_DAC_DEF, "<BHB", channel, value, 1)
+            sleep_ms(250)  # DAC requires at leas 250ms to update after a write.
+        elif channel_type == "din":
+            deb_mode = kwargs.get("debounce_mode", "simple")
+            self.opta._cmd(
+                self.addr,
+                _CMD_CFG_ANALOG_DIN,
+                "BBBBBBBBB",
+                channel,
+                get_bool("filtered", True),
+                get_bool("inverted", False),
+                get_bool("comparator", True),
+                1 if (deb_mode is None or deb_mode == "simple") else 2,
+                get_bool("scale", False),
+                kwargs.get("threshold", 9),
+                kwargs.get("sink", 1),
+                kwargs.get("debounce_time", 0 if deb_mode is None else 24),
+            )
+        elif channel_type == "pwm":
+            if channel > 4:
+                raise ValueError("Invalid PWM channel specified")
+            if "period" not in kwargs:
+                raise ValueError("PWM requires a period argument")
+            period = kwargs["period"]
+            duty = int(kwargs.get("duty", 50) / 100 * period)
+            self.opta._cmd(self.addr, _CMD_CFG_ANALOG_PWM, "<BII", channel, period, duty)
+            if "default_period" in kwargs:
+                period = kwargs["default_period"]
+                duty = int(kwargs.get("default_duty", 50) / 100 * period)
+                self.opta._cmd(self.addr, _CMD_SET_ANALOG_PWM_DEF, "<BII", channel, period, duty)
+
+        # Save channel type for later.
+        self.channels[channel] = channel_type
+
+
+class Opta:
+    def __init__(self, bus_id, freq=400_000, det=None):
+        """
+        Initializes an Opta controller.
+
+        Parameters:
+            - bus_id : The I2C bus identifier.
+            - freq : I2C bus frequency (default=400_000).
+            - det : GPIO pin used for bus detection (default is a PULL_UP input pin named "BUS_DETECT").
+        """
+        self.bus = I2C(bus_id, freq=freq)
+        self.cmd_buf = memoryview(bytearray(256 + 2))
+        self.det = Pin("BUS_DETECT", Pin.IN, Pin.PULL_UP) if det is None else det
+        self.exp_types = {
+            0x02: ("digital", "Opta Digital Mechanical"),
+            0x03: ("digital", "Opta Digital Solid State"),
+            0x04: ("analog", "Opta Analog"),
+            0x05: ("digital", "UNO R4 MINIMA"),
+        }
+
+    def _log_debug(self, msg):
+        # Blue protocol prints in blue
+        logging.debug(f"\033[94m{msg}\033[0m")
+
+    def _log_enabled(self, level):
+        return logging.getLogger().isEnabledFor(level)
+
+    def _bus_read(self, addr, buf):
+        self.bus.readfrom_into(addr, buf)
+        if self._log_enabled(logging.DEBUG):
+            self._log_debug("Recv: " + " ".join(["%02X" % (a) for a in buf]))
+
+    def _bus_write(self, addr, buf):
+        if self._log_enabled(logging.DEBUG):
+            self._log_debug("Send: " + " ".join(["%02X" % (a) for a in buf]))
+        self.bus.writeto(addr, buf)
+
+    def _crc8(self, buf, poly=0x07, crc=0x00):
+        for byte in buf:
+            crc ^= byte
+            for bit in range(8):
+                crc = (crc << 1) ^ poly if crc & 0x80 else crc << 1
+        return crc & 0xFF
+
+    def _cmd(self, addr, cmd, fmt=None, *args):
+        plen = 0 if fmt is None else struct.calcsize(fmt)
+        struct.pack_into("BBB", self.cmd_buf, 0, cmd[0], cmd[1], plen)
+        # Pack args (if any)
+        if fmt is not None:
+            struct.pack_into(fmt, self.cmd_buf, 3, *args)
+        self.cmd_buf[_CMD_HDR_LEN + plen] = self._crc8(self.cmd_buf[0 : _CMD_HDR_LEN + plen])
+        self._bus_write(addr, self.cmd_buf[0 : _CMD_HDR_LEN + _CMD_CRC_LEN + plen])
+        if cmd[2] == 0 and not cmd[3]:
+            return
+        # Command has a response payload or an ACK.
+        plen = 0 if cmd[3] else cmd[2]
+        # Expected CMD and DIR
+        exp_cmd = 0x20 if cmd[3] else cmd[1]
+        exp_dir = 0x03 if cmd[0] == _CMD_DIR_GET else 0x04
+
+        # Read and check response
+        self._bus_read(addr, self.cmd_buf[0 : _CMD_HDR_LEN + _CMD_CRC_LEN + plen])
+        # Check CMD, ARG and LEN
+        if self.cmd_buf[0] != exp_dir or self.cmd_buf[1] != exp_cmd or self.cmd_buf[2] != plen:
+            raise ValueError("Unexpected response: " + "".join("%02X" % b for b in self.cmd_buf[0:3]))
+
+        # Check CRC
+        if self.cmd_buf[_CMD_HDR_LEN + plen] != self._crc8(self.cmd_buf[0 : _CMD_HDR_LEN + plen]):
+            raise ValueError("Invalid CRC")
+        if not cmd[3]:
+            return self.cmd_buf[_CMD_HDR_LEN : _CMD_HDR_LEN + plen]
+
+    def _reset_bus(self, addr):
+        self._cmd(addr, _CMD_CHIP_RESET, "B", 0x56)
+        sleep_ms(2000)
+
+    def _set_address(self, addr, addr_new=None):
+        if addr_new is not None:
+            if self._log_enabled(logging.DEBUG):
+                self._log_debug(f"set address: 0x{addr:02X} new_address: 0x{addr_new:02X}")
+            return self._cmd(addr, _CMD_SET_ADDRESS, "B", addr_new)
+        return self._cmd(addr, _CMD_GET_ADDRESS)
+
+    def enum_devices(self):
+        """
+        Initializes the bus, resets all expansions, and returns a list of detected expansions.
+        Returns: A list of detected expansions on the bus.
+        """
+        detected = False
+        expansion_list = []
+
+        # Reset the first, last or temp device on the bus.
+        for addr in [_MIN_ADDRESS, _MAX_ADDRESS, _TMP_ADDRESS]:
+            try:
+                self._reset_bus(addr)
+                detected = True
+                break
+            except Exception as e:
+                logging.debug(e)
+
+        if not detected:
+            raise RuntimeError("No expansions detected on the bus")
+
+        addr = _MAX_ADDRESS
+        # Assign temp I2C addresses to expansions.
+        while not self.det.value():
+            self._set_address(0x0A, addr_new=addr)
+            sleep_ms(100)
+            try:
+                xaddr, xtype = self._set_address(addr)
+                if xaddr == addr:
+                    addr += 1
+                if self._log_enabled(logging.DEBUG):
+                    self._log_debug(f"phase 1 type: 0x{xtype:02X} address: 0x{xaddr:02X}")
+            except Exception as e:
+                logging.debug(e)
+
+        # Assign final I2C addresses to expansions.
+        for addr_new in range(_MIN_ADDRESS, _MIN_ADDRESS + addr - _MAX_ADDRESS):
+            self._set_address(addr - 1, addr_new)
+            sleep_ms(100)
+            try:
+                xaddr, xtype = self._set_address(addr_new)
+                addr -= 1
+                if self._log_enabled(logging.DEBUG):
+                    self._log_debug(f"phase 2 type: 0x{xtype:02X} address: 0x{xaddr:02X}")
+                if xtype not in self.exp_types:
+                    raise RuntimeError("Unsupported expansion type %d" % xtype)
+                expansion_list.append(Expansion(self, self.exp_types[xtype][0], xaddr, self.exp_types[xtype][1]))
+
+            except Exception as e:
+                logging.debug(e)
+
+        return expansion_list