diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index aee94aa2..82f5d5d2 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -32,6 +32,10 @@ add_custom_command(TARGET lcov
 # add tests
 #
 
+list(APPEND testdirs
+  unit/bacnet/bits
+  )
+
 list(APPEND testdirs
   bacnet/abort
   bacnet/alarm_ack
diff --git a/test/unit/bacnet/bits/CMakeLists.txt b/test/unit/bacnet/bits/CMakeLists.txt
new file mode 100644
index 00000000..be820026
--- /dev/null
+++ b/test/unit/bacnet/bits/CMakeLists.txt
@@ -0,0 +1,41 @@
+# SPDX-License-Identifier: MIT
+
+cmake_minimum_required(VERSION 3.10 FATAL_ERROR)
+
+get_filename_component(basename ${CMAKE_CURRENT_SOURCE_DIR} NAME)
+project(test_${basename}
+	VERSION 1.0.0
+	LANGUAGES C)
+
+
+string(REGEX REPLACE
+    "/test/unit/bacnet/[a-zA-Z_/-]*$"
+    "/src"
+    SRC_DIR
+    ${CMAKE_CURRENT_SOURCE_DIR})
+string(REGEX REPLACE
+    "/test/unit/bacnet/[a-zA-Z_/-]*$"
+    "/test"
+    TST_DIR
+    ${CMAKE_CURRENT_SOURCE_DIR})
+set(ZTST_DIR "${TST_DIR}/ztest/src")
+
+add_compile_definitions(
+	BIG_ENDIAN=0
+	CONFIG_ZTEST=1
+	)
+
+include_directories(
+	${SRC_DIR}
+	${TST_DIR}/ztest/include
+	)
+
+add_executable(${PROJECT_NAME}
+    # File(s) under test
+    #   NOTE: bits.h contains the complete implementation of the API.
+    # Support files and stubs (pathname alphabetical)
+    # Test and test library files
+	./src/main.c
+	${ZTST_DIR}/ztest_mock.c
+	${ZTST_DIR}/ztest.c
+	)
diff --git a/test/unit/bacnet/bits/src/main.c b/test/unit/bacnet/bits/src/main.c
new file mode 100644
index 00000000..77b429cf
--- /dev/null
+++ b/test/unit/bacnet/bits/src/main.c
@@ -0,0 +1,183 @@
+/*
+ * Copyright (c) 2023 Legrand North America, LLC.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+
+#include <zephyr/ztest.h>
+
+#undef BIT
+#undef _BV
+#undef BIT_SET
+#undef BIT_CLEAR
+#undef BIT_FLIP
+#undef BIT_CHECK
+#undef BITMASK_SET
+#undef BITMASK_CLEAR
+#undef BITMASK_FLIP
+#undef BITMASK_CHECK
+
+#include "bacnet/bits.h"
+
+
+/* NOTE: These tests must be compatible with C90, so they do not
+ * verify support for ULL.
+ */
+
+static void test_BIT(void)
+{
+    unsigned int bitpos = sizeof(unsigned int) * 8;
+
+    do {
+	bitpos -= 1;
+        zassert_true(BIT(bitpos) == (1U << bitpos), NULL);
+    } while (bitpos > 0);
+}
+
+static void test__BV(void)
+{
+    unsigned int bitpos = sizeof(unsigned int) * 8;
+
+    do {
+	bitpos -= 1;
+        zassert_true(BIT(bitpos) == (1U << bitpos), NULL);
+    } while (bitpos > 0);
+}
+
+static void test_BIT_SET(void)
+{
+    unsigned int bitpos = sizeof(unsigned int) * 8;
+
+    do {
+        unsigned int a = 0U;
+	bitpos -= 1;
+	BIT_SET(a, bitpos);
+        zassert_true(a == (1U << bitpos), NULL);
+    } while (bitpos > 0);
+}
+
+static void test_BIT_CLEAR(void)
+{
+    unsigned int bitpos = sizeof(unsigned int) * 8;
+
+    do {
+        unsigned int a = ~0U;
+	bitpos -= 1;
+	BIT_CLEAR(a, bitpos);
+        zassert_true(~(a) == (1U << bitpos), NULL);
+    } while (bitpos > 0);
+}
+
+static void test_BIT_FLIP(void)
+{
+    unsigned int bitpos = sizeof(unsigned int) * 8;
+
+    do {
+        unsigned int a = ~0U;
+	bitpos -= 1;
+	BIT_FLIP(a, bitpos);
+        zassert_true(a == ~(1U << bitpos), NULL);
+	BIT_FLIP(a, bitpos);
+        zassert_true(a == ~0U, NULL);
+
+	a = 0U;
+	BIT_FLIP(a, bitpos);
+        zassert_true(a == (1U << bitpos), NULL);
+	BIT_FLIP(a, bitpos);
+        zassert_true(a == 0U, NULL);
+	
+    } while (bitpos > 0);
+}
+
+static void test_BIT_CHECK(void)
+{
+    unsigned int bitpos = sizeof(unsigned int) * 8;
+
+    do {
+        unsigned int a = ~0U;
+	bitpos -= 1;
+	zassert_true(BIT_CHECK(a, bitpos), NULL);
+
+	a = 0U;
+	zassert_false(BIT_CHECK(a, bitpos), NULL);
+	
+    } while (bitpos > 0);
+}
+
+static void test_BITMASK_SET(void)
+{
+    unsigned int bitpos = sizeof(unsigned int) * 8;
+
+    do {
+        unsigned int a = 0U;
+	bitpos -= 1;
+	BITMASK_SET(a, (1U << bitpos));
+        zassert_true(a == (1U << bitpos), NULL);
+    } while (bitpos > 0);
+}
+
+static void test_BITMASK_CLEAR(void)
+{
+    unsigned int bitpos = sizeof(unsigned int) * 8;
+
+    do {
+        unsigned int a = ~0U;
+	bitpos -= 1;
+	BITMASK_CLEAR(a, (1U << bitpos));
+        zassert_true(~(a) == (1U << bitpos), NULL);
+    } while (bitpos > 0);
+}
+
+static void test_BITMASK_FLIP(void)
+{
+    unsigned int bitpos = sizeof(unsigned int) * 8;
+
+    do {
+        unsigned int a = ~0U;
+	bitpos -= 1;
+	BITMASK_FLIP(a, (1U << bitpos));
+        zassert_true(a == ~(1U << bitpos), NULL);
+	BITMASK_FLIP(a, (1U << bitpos));
+        zassert_true(a == ~0U, NULL);
+
+	a = 0U;
+	BITMASK_FLIP(a, (1U << bitpos));
+        zassert_true(a == (1U << bitpos), NULL);
+	BITMASK_FLIP(a, (1U << bitpos));
+        zassert_true(a == 0U, NULL);
+	
+    } while (bitpos > 0);
+}
+
+static void test_BITMASK_CHECK(void)
+{
+    unsigned int bitpos = sizeof(unsigned int) * 8;
+
+    do {
+        unsigned int a = ~0U;
+	bitpos -= 1;
+	zassert_true(BITMASK_CHECK(a, (1U << bitpos)), NULL);
+
+	a = 0U;
+	zassert_false(BITMASK_CHECK(a, (1U << bitpos)), NULL);
+	
+    } while (bitpos > 0);
+}
+
+void test_main(void)
+{
+    ztest_test_suite(bacnet_bits,
+     ztest_unit_test(test_BIT),
+     ztest_unit_test(test__BV),
+     ztest_unit_test(test_BIT_SET),
+     ztest_unit_test(test_BIT_CLEAR),
+     ztest_unit_test(test_BIT_FLIP),
+     ztest_unit_test(test_BIT_CHECK),
+     ztest_unit_test(test_BITMASK_SET),
+     ztest_unit_test(test_BITMASK_CLEAR),
+     ztest_unit_test(test_BITMASK_FLIP),
+     ztest_unit_test(test_BITMASK_CHECK)
+     );
+    ztest_run_test_suite(bacnet_bits);
+}
diff --git a/zephyr/tests/unit/bacnet/bits/CMakeLists.txt b/zephyr/tests/unit/bacnet/bits/CMakeLists.txt
new file mode 100644
index 00000000..7e2d817d
--- /dev/null
+++ b/zephyr/tests/unit/bacnet/bits/CMakeLists.txt
@@ -0,0 +1,26 @@
+# Copyright (c) 2022 Legrand North America, LLC.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+
+if(NOT ZEPHYR_CURRENT_MODULE_DIR)
+  string(REGEX REPLACE "/zephyr/tests/[a-zA-Z_/-]*$" ""
+    ZEPHYR_CURRENT_MODULE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
+endif()
+
+set(SOURCES
+  ${ZEPHYR_CURRENT_MODULE_DIR}/test/unit/bacnet/bits/src/main.c
+  )
+
+project(bacnet_bits)
+find_package(Zephyr COMPONENTS unittest REQUIRED HINTS $ENV{ZEPHYR_BASE})
+
+# NOTE for Zephyr >= v3.2.0:
+# - Zephyr unittest builds for target 'testbinary' instead of 'app'.
+# - Zephyr unittest does not generate ZEPHYR_<modulename>_MODULE_DIR.
+# So we have to use relative paths to get to the source.
+
+target_include_directories(testbinary PRIVATE
+  ${ZEPHYR_CURRENT_MODULE_DIR}/src
+  )
diff --git a/zephyr/tests/unit/bacnet/bits/prj.conf b/zephyr/tests/unit/bacnet/bits/prj.conf
new file mode 100644
index 00000000..d41d3a24
--- /dev/null
+++ b/zephyr/tests/unit/bacnet/bits/prj.conf
@@ -0,0 +1 @@
+# This file is intentionally empty
diff --git a/zephyr/tests/unit/bacnet/bits/testcase.yaml b/zephyr/tests/unit/bacnet/bits/testcase.yaml
new file mode 100644
index 00000000..c9418b1d
--- /dev/null
+++ b/zephyr/tests/unit/bacnet/bits/testcase.yaml
@@ -0,0 +1,3 @@
+tests:
+  bacnet.bits.unit:
+    type: unit