diff --git a/.gitmodules b/.gitmodules
index e69de29bb..ed69927d6 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "tests/arduino_core_tests"]
+	path = tests/arduino_core_tests
+	url = https://github.com/Infineon/arduino-core-tests.git
diff --git a/tests/README.md b/tests/README.md
new file mode 100644
index 000000000..52ad2880b
--- /dev/null
+++ b/tests/README.md
@@ -0,0 +1,53 @@
+# Arduino core test configuration
+
+Configuration for the shared
+[`arduino-core-tests`](https://github.com/Infineon/arduino-core-tests) suite
+(vendored at [`arduino_core_tests`](arduino_core_tests)) lives
+in a single file, `tests/test_config.h`, exactly where that submodule's own
+Makefile expects it (`../../tests/test_config.h`, relative to the submodule).
+
+One file, with a `#if defined(ARDUINO_<BOARD>)` block per board.
+`arduino-cli` already defines `ARDUINO_{build.board}` for every compile, so
+the right block is selected automatically.
+
+## Adding a board
+
+1. Add a `#if defined(ARDUINO_<BOARD>)` block to `tests/test_config.h`, using
+   the board's `build.board` value from `boards.txt` (e.g. `KIT_PSE84_AI`).
+2. Define the pins required by the selected tests, using Arduino pin numbers
+   (e.g. `D0`), not MCU port/pin names.
+3. Verify each Arduino pin against the board's variant overlay
+   (`variants/<variant>/*.overlay`, `zephyr,user` / `digital-pin-gpios`) and
+   the board schematic or official pinout.
+4. Document any required jumpers or external connections next to the block.
+
+For example, `test_digitalio_single` requires two physically connected GPIOs:
+
+```c
+#if defined(ARDUINO_<BOARD>)
+#define TEST_PIN_DIGITAL_IO_OUTPUT <output pin>
+#define TEST_PIN_DIGITAL_IO_INPUT <input pin>
+#endif
+```
+
+## Running a test
+
+```bash
+make -C tests/arduino_core_tests FQBN=<fqbn> UNITY_PATH=Unity \
+  TESTS=-DTEST_DIGITALIO_SINGLE test_digitalio_single compile
+```
+
+To flash and run on a single connected board, add `PORT=` and
+`ENABLE_SYNC=0`:
+
+```bash
+make -C tests/arduino_core_tests FQBN=<fqbn> UNITY_PATH=Unity PORT=<port> \
+  TESTS=-DTEST_DIGITALIO_SINGLE ENABLE_SYNC=0 test_digitalio_single
+```
+
+`ENABLE_SYNC` defaults to `1`: tests named `*_connected2_*` (e.g.
+`test_wire_connected2_masterpingpong`) need two boards and wait for each
+other's handshake over serial, so leave it enabled for those. Tests named
+`*_single` (or loopback tests like `test_spi_connected1_loopback`) only use
+one board; without `ENABLE_SYNC=0` they hang forever printing
+`synchronising with host...`, since nothing ever answers the handshake.
diff --git a/tests/arduino_core_tests b/tests/arduino_core_tests
new file mode 160000
index 000000000..0f52c0291
--- /dev/null
+++ b/tests/arduino_core_tests
@@ -0,0 +1 @@
+Subproject commit 0f52c0291cc344206846c01cfbc8590fab0844f7
diff --git a/tests/test_config.h b/tests/test_config.h
new file mode 100644
index 000000000..545a776b7
--- /dev/null
+++ b/tests/test_config.h
@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) Infineon Technologies AG
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Board-specific test pin definitions for tests/arduino_core_tests.
+ *
+ * Each board adds its own #if defined(ARDUINO_<BOARD>) block below (see
+ * tests/README.md). This file intentionally has no board blocks of its own:
+ * board-specific content belongs to the branch that owns that board.
+ */
+#ifndef TEST_CONFIG_H
+#define TEST_CONFIG_H
+
+#endif // TEST_CONFIG_H