boards: shields: Add Adafruit MCP4728 DAC shield

boards/shields/adafruit_mcp4728/Kconfig.shield

@@ -0,0 +1,5 @@
+# Copyright (c) 2025 Jonas Berg
+# SPDX-License-Identifier: Apache-2.0
+
+config SHIELD_ADAFRUIT_MCP4728
+	def_bool $(shields_list_contains,adafruit_mcp4728)

boards/shields/adafruit_mcp4728/adafruit_mcp4728.overlay

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2025 Jonas Berg
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/ {
+	zephyr,user {
+		dac = <&dac_adafruit_mcp4728>;
+		dac-channel-id = <0>;
+		dac-resolution = <12>;
+	};
+};
+
+&zephyr_i2c {
+	status = "okay";
+
+	dac_adafruit_mcp4728: dac@60 {
+		status = "okay";
+		compatible = "microchip,mcp4728";
+		reg = <0x60>;
+		#io-channel-cells = <1>;
+		voltage-reference = <01 01 01 01>; /* Internal reference (2.048V) */
+		power-down-mode = <00 00 00 00>; /* Normal mode */
+	};
+};

boards/shields/adafruit_mcp4728/doc/index.rst

@@ -0,0 +1,75 @@
+.. _adafruit_mcp4728:
+
+Adafruit MCP4728 Quad DAC Shield
+################################
+
+Overview
+********
+
+The `Adafruit MCP4728 Quad DAC Shield`_ features a `Microchip 12-Bit Quad Output DAC`_ and
+two STEMMA QT connectors. It has four output channels and an internal voltage reference.
+
+.. figure:: adafruit_mcp4728.webp
+   :align: center
+   :alt: Adafruit MCP4728 DAC Shield
+
+   Adafruit MCP4728 DAC Shield (Credit: Adafruit)
+
+
+Requirements
+************
+
+This shield can be used with boards which provide an I2C connector, for
+example STEMMA QT or Qwiic connectors.
+The target board must define a ``zephyr_i2c`` node label.
+See :ref:`shields` for more details.
+
+
+Pin Assignments
+===============
+
++--------------+-------------------------------------------------+
+| Shield Pin   | Function                                        |
++==============+=================================================+
+| SCL          | MCP4728 I2C SCL                                 |
++--------------+-------------------------------------------------+
+| SDA          | MCP4728 I2C SDA                                 |
++--------------+-------------------------------------------------+
+| LDAC         | MCP4728 load DAC input                          |
++--------------+-------------------------------------------------+
+| RDY          | MCP4728 ready. Low when busy with EEPROM write. |
++--------------+-------------------------------------------------+
+| VA - VD      | MCP4728 output channels                         |
++--------------+-------------------------------------------------+
+
+When using this shield via the STEMMA QT connector, the supply voltage is 3.3 Volt, so the
+maximum internal voltage reference that can be used is 2.048 Volt.
+
+The LDAC pin is pulled down on the shield, forcing an updated output voltage as soon as
+the input register has been written.
+
+See :dtcompatible:`microchip,mcp4728` for documentation on how to adjust the
+devicetree file, for example to adjust the voltage reference, gain or power-down mode.
+
+
+Programming
+***********
+
+Set ``--shield adafruit_mcp4728`` when you invoke ``west build``. For example
+when running the :zephyr:code-sample:`dac` sample:
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/drivers/dac
+   :board: adafruit_feather_adalogger_rp2040
+   :shield: adafruit_mcp4728
+   :goals: build flash
+
+Connect a voltmeter to the shield output ``VA`` and observe how the voltage changes.
+To run the sample for another output channel, modify the value for the ``dac-channel-id``
+attribute in the .overlay file for this shield.
+
+.. _Adafruit MCP4728 Quad DAC Shield:
+   https://learn.adafruit.com/adafruit-mcp4728-i2c-quad-dac
+
+.. _Microchip 12-Bit Quad Output DAC:
+   https://www.microchip.com/en-us/product/mcp4728

boards/shields/adafruit_mcp4728/shield.yml

@@ -0,0 +1,10 @@
+# SPDX-License-Identifier: Apache-2.0
+#
+# Copyright (c) 2025, Jonas Berg
+
+shield:
+  name: adafruit_mcp4728
+  full_name: Adafruit MCP4728 DAC Shield
+  vendor: adafruit
+  supported_features:
+    - dac

samples/drivers/dac/sample.yaml

@@ -16,5 +16,7 @@ tests:
   sample.drivers.dac.shields:
     platform_allow:
       - adafruit_feather_rp2040/rp2040
+      - adafruit_feather_adalogger_rp2040/rp2040
     extra_args:
       - platform:adafruit_feather_rp2040/rp2040:SHIELD="adafruit_ad5693r"
+      - platform:adafruit_feather_adalogger_rp2040/rp2040:SHIELD="adafruit_mcp4728"