boards: shields: Add Adafruit HTS221 humidity sensor shield

Tested with the command mentioned in index.rst

Compile testing of the overlay file is done via
the dht_polling sample.

Product photo from https://learn.adafruit.com/assets/89387

Signed-off-by: Jonas Berg <jonas.s.t.berg@gmail.com>

boards/shields/adafruit_hts221/Kconfig.shield

@@ -0,0 +1,5 @@
+# Copyright (c) 2026 Jonas Berg
+# SPDX-License-Identifier: Apache-2.0
+
+config SHIELD_ADAFRUIT_HTS221
+	def_bool $(shields_list_contains,adafruit_hts221)

boards/shields/adafruit_hts221/adafruit_hts221.overlay

@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2026 Jonas Berg
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/ {
+	aliases {
+		dht0 = &adafruit_hts221;
+	};
+};
+
+&zephyr_i2c {
+	status = "okay";
+
+	adafruit_hts221: hts221@5f {
+		status = "okay";
+		compatible = "st,hts221";
+		reg = <0x5f>;
+	};
+};

boards/shields/adafruit_hts221/doc/index.rst

@@ -0,0 +1,63 @@
+.. _adafruit_hts221:
+
+Adafruit HTS221 Shield
+######################
+
+Overview
+********
+
+The `Adafruit HTS221 Temperature and Humidity Sensor Shield`_ features
+a `ST Microelectronics HTS221 Humidity and Temperature Sensor`_ and two STEMMA QT connectors.
+It measures temperature and humidity.
+
+.. figure:: adafruit_hts221.webp
+   :align: center
+   :alt: Adafruit HTS221 Shield
+
+   Adafruit HTS221 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          | I2C SDA                            |
++--------------+------------------------------------+
+| SCL          | I2C SCL                            |
++--------------+------------------------------------+
+| DRDY         | Data ready output                  |
++--------------+------------------------------------+
+| CS           | Keep at high level to use I2C mode |
++--------------+------------------------------------+
+
+See :dtcompatible:`st,hts221` for details on possible devicetree settings, for example if you
+are using the DRDY pin.
+
+
+Programming
+***********
+
+Set ``--shield adafruit_hts221`` 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_feather_scorpio_rp2040
+   :shield: adafruit_hts221
+   :goals: build flash
+
+.. _Adafruit HTS221 Temperature and Humidity Sensor Shield:
+   https://learn.adafruit.com/adafruit-hts221-temperature-humidity-sensor
+
+.. _ST Microelectronics HTS221 Humidity and Temperature Sensor:
+   https://www.st.com/resource/en/datasheet/hts221.pdf

boards/shields/adafruit_hts221/shield.yml

@@ -0,0 +1,10 @@
+# SPDX-License-Identifier: Apache-2.0
+#
+# Copyright (c) 2026, Jonas Berg
+
+shield:
+  name: adafruit_hts221
+  full_name: Adafruit HTS221 Temperature and Humidity Sensor Shield
+  vendor: adafruit
+  supported_features:
+    - sensor

samples/sensor/dht_polling/sample.yaml

@@ -17,11 +17,13 @@ tests:
       - adafruit_qt_py_rp2040/rp2040
       - adafruit_feather_rp2040/rp2040
       - adafruit_feather_canbus_rp2040/rp2040
+      - adafruit_feather_scorpio_rp2040/rp2040
       - nucleo_f401re
     extra_args:
       - platform:adafruit_qt_py_rp2040/rp2040:SHIELD="adafruit_aht20"
       - platform:adafruit_feather_rp2040/rp2040:SHIELD="adafruit_sht4x"
       - platform:adafruit_feather_canbus_rp2040/rp2040:SHIELD="sparkfun_shtc3"
+      - platform:adafruit_feather_scorpio_rp2040/rp2040:SHIELD="adafruit_hts221"
     harness: console
     harness_config:
       fixture: fixture_i2c_hs300x