Add support for PCA9547D devices

adafruit_tca9548a.py

@@ -135,3 +135,29 @@ def __getitem__(self, key: Literal[0, 1, 2, 3]) -> "TCA9548A_Channel":
         if self.channels[key] is None:
             self.channels[key] = TCA9548A_Channel(self, key)
         return self.channels[key]
+
+
+class TCA9547D_Channel(TCA9548A_Channel):
+    """Helper class to represent an output channel on the TCA9547D and take care
+    of the necessary I2C commands for channel switching. This class needs to
+    behave like an I2CDevice."""
+
+    def __init__(self, tca: "TCA9547D", channel: int) -> None:
+        super().__init__(tca, channel)
+        self.tca = tca
+        """
+        B3 enables/disables the mux. B2-B0 control which channel is used.
+        ref: https://www.nxp.com/docs/en/data-sheet/PCA9547.pdf
+        """
+        self.channel_switch = (channel + (1 << 3)).to_bytes(1, "little")
+
+
+class TCA9547D(TCA9548A):
+    """Class which provides interface to TCA9547D I2C multiplexer."""
+
+    def __getitem__(self, key: Literal[0, 1, 2, 3, 4, 5, 6, 7]) -> "TCA9548A_Channel":
+        if not 0 <= key <= 7:
+            raise IndexError("Channel must be an integer in the range: 0-7.")
+        if self.channels[key] is None:
+            self.channels[key] = TCA9547D_Channel(self, key)
+        return self.channels[key]

examples/tca9547d_multisensor.py

@@ -0,0 +1,25 @@
+# SPDX-FileCopyrightText: 2021 ladyada for Adafruit Industries
+# SPDX-License-Identifier: MIT
+
+# This example shows using two TSL2491 light sensors attached to TCA9547D channels 0 and 1.
+# Use with other I2C sensors would be similar.
+import time
+import board
+import adafruit_tsl2591
+import adafruit_tca9548a
+
+# Create I2C bus as normal
+i2c = board.I2C()  # uses board.SCL and board.SDA
+# i2c = board.STEMMA_I2C()  # For using the built-in STEMMA QT connector on a microcontroller
+
+# Create the TCA9548A object and give it the I2C bus
+tca = adafruit_tca9548a.TCA9547D(i2c)
+
+# For each sensor, create it using the TCA9548A channel instead of the I2C object
+tsl1 = adafruit_tsl2591.TSL2591(tca[0])
+tsl2 = adafruit_tsl2591.TSL2591(tca[1])
+
+# After initial setup, can just use sensors as normal.
+while True:
+    print(tsl1.lux, tsl2.lux)
+    time.sleep(0.1)

examples/tca9547d_simpletest.py

@@ -0,0 +1,20 @@
+# SPDX-FileCopyrightText: 2021 Carter Nelson for Adafruit Industries
+# SPDX-License-Identifier: MIT
+
+# This example shows using TCA9547D to perform a simple scan for connected devices
+import board
+import adafruit_tca9548a
+
+# Create I2C bus as normal
+i2c = board.I2C()  # uses board.SCL and board.SDA
+# i2c = board.STEMMA_I2C()  # For using the built-in STEMMA QT connector on a microcontroller
+
+# Create the TCA95487D object and give it the I2C bus
+tca = adafruit_tca9548a.TCA9547D(i2c)
+
+for channel in range(8):
+    if tca[channel].try_lock():
+        print("Channel {}:".format(channel), end="")
+        addresses = tca[channel].scan()
+        print([hex(address) for address in addresses if address != 0x70])
+        tca[channel].unlock()