boards: shields: Add Adafruit AHT20 temp and humidity sensor shield

Product photo from https://learn.adafruit.com/assets/91687
with the licence CC BY 3.0

Tested with the command mentioned on the index.rst page.

Signed-off-by: Jonas Berg <[email protected]>

Author: pyhys

boards/shields/adafruit_aht20/Kconfig.shield

@@ -0,0 +1,5 @@
+# Copyright (c) 2025 Jonas Berg
+# SPDX-License-Identifier: Apache-2.0
+
+config SHIELD_ADAFRUIT_AHT20
+	def_bool $(shields_list_contains,adafruit_aht20)

boards/shields/adafruit_aht20/adafruit_aht20.overlay

@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2025 Jonas Berg
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/ {
+	aliases {
+		dht0 = &adafruit_aht20;
+	};
+};
+
+&zephyr_i2c {
+	status = "okay";
+
+	adafruit_aht20: aht20@38 {
+		status = "okay";
+		compatible = "aosong,aht20";
+		reg = <0x38>;
+	};
+};

boards/shields/adafruit_aht20/doc/adafruit_aht20.webp

@@ -0,0 +1,59 @@
+.. _adafruit_aht20:
+
+Adafruit AHT20 Shield
+#####################
+
+Overview
+********
+
+The `Adafruit AHT20 Temperature and Humidity Sensor Shield`_ features
+an `Aosong AHT20 Humidity and Temperature Sensor`_ and two STEMMA QT connectors.
+It measures temperature and humidity.
+
+.. figure:: adafruit_aht20.webp
+   :align: center
+   :alt: Adafruit AHT20 Shield
+
+   Adafruit AHT20 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          |
++==============+===================+
+| SDA          | AHT20 I2C SDA     |
++--------------+-------------------+
+| SCL          | AHT20 I2C SCL     |
++--------------+-------------------+
+
+See :dtcompatible:`aosong,aht20` for details on possible devicetree settings.
+
+
+Programming
+***********
+
+Set ``--shield adafruit_aht20`` when you invoke ``west build``. For example
+when running the :zephyr:code-sample:`dht_polling` sample:
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/sensor/dht_polling
+   :board: adafruit_qt_py_rp2040
+   :shield: adafruit_aht20
+   :goals: build
+
+.. _Adafruit AHT20 Temperature and Humidity Sensor Shield:
+   https://learn.adafruit.com/adafruit-aht20
+
+.. _Aosong AHT20 Humidity and Temperature Sensor:
+   https://www.aosong.com/userfiles/files/media/Data%20Sheet%20AHT20.pdf

boards/shields/adafruit_aht20/doc/index.rst

@@ -0,0 +1,10 @@
+# SPDX-License-Identifier: Apache-2.0
+#
+# Copyright (c) 2025, Jonas Berg
+
+shield:
+  name: adafruit_aht20
+  full_name: Adafruit AHT20 Temperature and Humidity Sensor Shield
+  vendor: adafruit
+  supported_features:
+    - sensor

boards/shields/adafruit_aht20/shield.yml

@@ -13,6 +13,11 @@ tests:
     filter: dt_alias_exists("dht0")
     integration_platforms:
       - nucleo_f401re
+    platform_allow:
+      - adafruit_qt_py_rp2040/rp2040
+      - nucleo_f401re
+    extra_args:
+      - platform:adafruit_qt_py_rp2040/rp2040:SHIELD="adafruit_aht20"
     harness: console
     harness_config:
       fixture: fixture_i2c_hs300x