matrix_keypad: add test application

tests/driver_matrix_keypad/Makefile

@@ -0,0 +1,7 @@
+include ../Makefile.tests_common
+
+# required modules
+USEMODULE += matrix_keypad
+USEMODULE += ztimer_msec
+
+include $(RIOTBASE)/Makefile.include

tests/driver_matrix_keypad/README.md

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+matrix_keypad
+=============
+
+This is a test application for the matrix_keypad module.
+
+Usage
+=====
+
+The test application will print the key row and column when it is pressed or
+released.

tests/driver_matrix_keypad/main.c

@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2022 Koen Zandberg
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     tests
+ * @{
+ *
+ * @file
+ * @brief       Test application for the matrix_keypad driver
+ *
+ * @author      Koen Zandberg <koen@bergzand.net>
+ *
+ * @}
+ */
+
+#include <stdio.h>
+
+#include "matrix_keypad.h"
+#include "matrix_keypad_params.h"
+#include "ztimer.h"
+
+void _callback(void *arg, size_t col, size_t row, bool state)
+{
+    (void)arg;
+    printf("Key switch at column %u and row %u is ", (unsigned)col, (unsigned)row);
+    if (state) {
+        puts("pressed!");
+    }
+    else {
+        puts("released!");
+    }
+}
+
+int main(void)
+{
+    matrix_keypad_t dev;
+
+    puts("Generated RIOT application: 'matrix_keypad'");
+    if (matrix_keypad_init(&dev, &matrix_keypad_params[0], _callback, NULL) == 0) {
+        puts("[OK]\n");
+    }
+
+    while (true) {
+        matrix_keypad_scan(&dev);
+        ztimer_sleep(ZTIMER_MSEC, 1);
+    }
+    return 0;
+}