tests/adc_ng_entropy: Small test for the ADC-NG entropy collection

tests/adc_ng_entropy/Makefile

@@ -0,0 +1,8 @@
+BOARD ?= arduino-nano
+include ../Makefile.tests_common
+
+USEMODULE += adc_ng
+USEMODULE += adc_ng_util
+USEMODULE += fmt
+
+include $(RIOTBASE)/Makefile.include

tests/adc_ng_entropy/main.c

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+/*
+ * Copyright (C) 2020 Otto-von-Guericke-Universität Magdeburg
+ *
+ * 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 ADC NG drivers
+ *
+ * @author      Marian Buschsieweke <marian.buschsieweke@ovgu.de>
+ *
+ * @}
+ */
+
+#include <stdlib.h>
+
+#include "adc_ng.h"
+#include "adc_ng_util.h"
+#include "fmt.h"
+
+int main(void)
+{
+    print_str(
+        "RIOT ADC NG NTC entropy driver test\n"
+        "===================================\n"
+        "\n"
+    );
+
+    while (1) {
+        int8_t entropy[16];
+        int retval = adc_ng_entropy(0, entropy, sizeof(entropy));
+        if (retval) {
+            print_str("adc_ng_entropy() failed with ");
+            print_s32_dec(retval);
+            print_str("\n");
+            return -1;
+        }
+        char buf[2];
+        fmt_byte_hex(buf, entropy[0]);
+        print(buf, 2);
+        for (unsigned i = 1; i < sizeof(entropy); i++) {
+            print(" ", 1);
+            fmt_byte_hex(buf, entropy[i]);
+            print(buf, 2);
+        }
+        print("\n", 1);
+    }
+
+    return 0;
+}