Diff: mbed-os/TESTS/mbed_drivers/timer/main.cpp

Revision:

0:8fdf9a60065b

diff -r 000000000000 -r 8fdf9a60065b mbed-os/TESTS/mbed_drivers/timer/main.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed-os/TESTS/mbed_drivers/timer/main.cpp	Wed Oct 10 00:33:53 2018 +0000
@@ -0,0 +1,791 @@
+/*
+ * Copyright (c) 2017, ARM Limited, All Rights Reserved
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "mbed.h"
+#include "greentea-client/test_env.h"
+#include "unity.h"
+#include "utest.h"
+#include "rtos.h"
+#include "hal/us_ticker_api.h"
+
+#if !DEVICE_USTICKER
+#error [NOT_SUPPORTED] test not supported
+#endif
+
+using namespace utest::v1;
+
+extern uint32_t SystemCoreClock;
+
+#define US_PER_SEC       1000000
+#define US_PER_MSEC      1000
+#define MSEC_PER_SEC     1000
+
+/*
+* Define tolerance as follows:
+* tolerance = 500 us + 2% of measured time
+*
+* e.g.
+* 1 ms delay: tolerance = 520 us
+* 10 ms delay: tolerance = 700 us
+* 100 ms delay: tolerance = 2500 us
+* 1000 ms delay: tolerance = 20500 us
+*
+*  */
+#ifdef NO_SYSTICK
+#define TOLERANCE 5
+#else
+#define TOLERANCE 2
+#endif
+
+#define DELTA_US(delay_ms) (500 + (delay_ms) * US_PER_MSEC  * TOLERANCE / 100)
+#define DELTA_MS(delay_ms) (1 + (delay_ms) * TOLERANCE / 100)
+#define DELTA_S(delay_ms) (0.000500f + ((float)(delay_ms)) * ((float)(TOLERANCE) / 100.f) / MSEC_PER_SEC)
+
+#define TICKER_FREQ_1MHZ 1000000
+#define TICKER_BITS 32
+
+static Timer *p_timer = NULL;
+
+/* Global variable used to simulate passage of time
+ * in case when timer which uses user ticker is tested.
+ */
+static uint32_t curr_ticker_ticks_val;
+
+
+/* Replacement for generic wait functions to avoid invoking OS scheduling stuff. */
+void busy_wait_us(int us)
+{
+    const ticker_data_t *const ticker = get_us_ticker_data();
+    uint32_t start = ticker_read(ticker);
+    while ((ticker_read(ticker) - start) < (uint32_t)us);
+}
+
+void busy_wait_ms(int ms)
+{
+    busy_wait_us(ms * US_PER_MSEC);
+}
+
+/* User ticker interface function. */
+static void stub_interface_init()
+{
+    /* do nothing. */
+}
+
+/* User ticker interface function - only this
+ * ticker interface function is used by Timer API. */
+static uint32_t stub_ticker_read(void)
+{
+    /* Simulate elapsed time. */
+    return curr_ticker_ticks_val;
+}
+
+/* User ticker interface function. */
+static void stub_disable_interrupt(void)
+{
+    /* do nothing. */
+}
+
+/* User ticker interface function. */
+static void stub_clear_interrupt(void)
+{
+    /* do nothing. */
+}
+
+/* User ticker interface function. */
+static void stub_set_interrupt(timestamp_t timestamp)
+{
+    /* do nothing. */
+}
+
+/* User ticker interface function. */
+static void stub_fire_interrupt(void)
+{
+    /* do nothing. */
+}
+
+/* User ticker interface function. */
+static void stub_free(void)
+{
+    /* do nothing. */
+}
+
+ticker_info_t info =
+{ TICKER_FREQ_1MHZ, TICKER_BITS };
+
+const ticker_info_t *stub_get_info(void)
+{
+    return &info;
+}
+
+/* User ticker event queue. */
+static ticker_event_queue_t my_events = { 0 };
+
+/* User ticker interface data. */
+static const ticker_interface_t us_interface = {
+    .init = stub_interface_init,
+    .read = stub_ticker_read, /* Only this function is used by the Timer. */
+    .disable_interrupt = stub_disable_interrupt,
+    .clear_interrupt = stub_clear_interrupt,
+    .set_interrupt = stub_set_interrupt,
+    .fire_interrupt = stub_fire_interrupt,
+    .free = stub_free,
+    .get_info = stub_get_info,
+};
+
+/* User ticker data structure. */
+static const ticker_data_t us_data = {
+    .interface = &us_interface,
+    .queue = &my_events
+};
+
+/* Function which returns user ticker data. */
+const ticker_data_t *get_user_ticker_data(void)
+{
+    return &us_data;
+}
+
+/* Initialisation of the Timer object which uses
+ * ticker data provided by the user.
+ *
+ * */
+utest::v1::status_t timer_user_ticker_setup_handler(const Case *const source, const size_t index_of_case)
+{
+    p_timer = new Timer(get_user_ticker_data());
+
+    /* Check if Timer object has been created. */
+    TEST_ASSERT_NOT_NULL(p_timer);
+
+    return greentea_case_setup_handler(source, index_of_case);
+}
+
+/* Initialisation of the Timer object which uses
+ * default os ticker data.
+ *
+ * */
+utest::v1::status_t timer_os_ticker_setup_handler(const Case *const source, const size_t index_of_case)
+{
+    p_timer = new Timer();
+
+    /* Check if Timer object has been created. */
+    TEST_ASSERT_NOT_NULL(p_timer);
+
+    return greentea_case_setup_handler(source, index_of_case);
+}
+
+/* Test finalisation.
+ *
+ * */
+utest::v1::status_t cleanup_handler(const Case *const source, const size_t passed, const size_t failed, const failure_t reason)
+{
+    delete p_timer;
+
+    p_timer = NULL;
+
+    return greentea_case_teardown_handler(source, passed, failed, reason);
+}
+
+/* This test verifies if timer is stopped after
+ * creation.
+ *
+ * Note: this function assumes that Timer uses os ticker.
+ *
+ * Given Timer has been successfully created.
+ * When read of timer elapsed time is requested.
+ * Then result is always 0.
+ */
+void test_timer_creation_os_ticker()
+{
+    /* Check results. */
+    TEST_ASSERT_EQUAL_FLOAT(0, p_timer->read());
+    TEST_ASSERT_EQUAL_INT32(0, p_timer->read_ms());
+    TEST_ASSERT_EQUAL_INT32(0, p_timer->read_us());
+    TEST_ASSERT_EQUAL_UINT64(0, p_timer->read_high_resolution_us());
+
+    /* Wait 10 ms.
+     * After that operation timer read routines should still return 0. */
+    busy_wait_ms(10);
+
+    /* Check results. */
+    TEST_ASSERT_EQUAL_FLOAT(0, p_timer->read());
+    TEST_ASSERT_EQUAL_INT32(0, p_timer->read_ms());
+    TEST_ASSERT_EQUAL_INT32(0, p_timer->read_us());
+    TEST_ASSERT_EQUAL_UINT64(0, p_timer->read_high_resolution_us());
+}
+
+/* This test verifies if timer is stopped after
+ * creation.
+ *
+ * Note: this function assumes that Timer uses user/fake ticker
+ * which returns time value provided in curr_ticker_ticks_val
+ * global variable.
+ *
+ * Given Timer has been successfully created.
+ * When read of timer elapsed time is requested.
+ * Then result is always 0.
+ */
+void test_timer_creation_user_ticker()
+{
+    /* For timer which is using user ticker simulate timer
+     * creation time (irrelevant in case of os ticker). */
+    curr_ticker_ticks_val = 10000;
+
+    /* Check results. */
+    TEST_ASSERT_EQUAL_FLOAT(0, p_timer->read());
+    TEST_ASSERT_EQUAL_INT32(0, p_timer->read_ms());
+    TEST_ASSERT_EQUAL_INT32(0, p_timer->read_us());
+    TEST_ASSERT_EQUAL_UINT64(0, p_timer->read_high_resolution_us());
+
+    /* Simulate that 10 ms has elapsed.
+     * After that operation timer read routines should still return 0. */
+    curr_ticker_ticks_val += 10000;
+
+    /* Check results. */
+    TEST_ASSERT_EQUAL_FLOAT(0, p_timer->read());
+    TEST_ASSERT_EQUAL_INT32(0, p_timer->read_ms());
+    TEST_ASSERT_EQUAL_INT32(0, p_timer->read_us());
+    TEST_ASSERT_EQUAL_UINT64(0, p_timer->read_high_resolution_us());
+}
+
+/* This test verifies verifies if read(), read_us(), read_ms(),
+ * read_high_resolution_us() functions returns valid values.
+ *
+ * Note: this function assumes that Timer uses user/fake ticker
+ * which returns time value provided in curr_ticker_ticks_val
+ * global variable.
+ *
+ * Given Timer has been successfully created and
+ * few times started and stopped after a specified period of time.
+ * When timer read request is performed.
+ * Then read functions return accumulated time elapsed between starts
+ * and stops.
+ */
+void test_timer_time_accumulation_user_ticker()
+{
+    /* Simulate that current time is equal to 0 us. */
+    curr_ticker_ticks_val = 0;
+
+    /* Start the timer. */
+    p_timer->start();
+
+    /* -- Simulate that current time is equal to 1 us -- */
+    curr_ticker_ticks_val = 1;
+
+    /* Stop the timer. */
+    p_timer->stop();
+
+    /* Check results - 1 us has elapsed. */
+    TEST_ASSERT_EQUAL_FLOAT(0.000001f, p_timer->read());
+    TEST_ASSERT_EQUAL_INT32(0, p_timer->read_ms());
+    TEST_ASSERT_EQUAL_INT32(1, p_timer->read_us());
+    TEST_ASSERT_EQUAL_UINT64(1, p_timer->read_high_resolution_us());
+
+    /* Simulate that 100 us has elapsed between stop and start. */
+    curr_ticker_ticks_val = 101;
+
+    /* Start the timer. */
+    p_timer->start();
+
+    /* -- Simulate that current time is equal to 225 us -- */
+    curr_ticker_ticks_val = 225;
+
+    /* Stop the timer. */
+    p_timer->stop();
+
+    /* Check results - 125 us have elapsed. */
+    TEST_ASSERT_EQUAL_FLOAT(0.000125f, p_timer->read());
+    TEST_ASSERT_EQUAL_INT32(0, p_timer->read_ms());
+    TEST_ASSERT_EQUAL_INT32(125, p_timer->read_us());
+    TEST_ASSERT_EQUAL_UINT64(125, p_timer->read_high_resolution_us());
+
+    /* Simulate that 100 us has elapsed between stop and start. */
+    curr_ticker_ticks_val = 325;
+
+    /* Start the timer. */
+    p_timer->start();
+
+    /* -- Simulate that current time is equal to 1200 us -- */
+    curr_ticker_ticks_val = 1200;
+
+    /* Stop the timer. */
+    p_timer->stop();
+
+    /* Check results - 1 ms has elapsed. */
+    TEST_ASSERT_EQUAL_FLOAT(0.001000f, p_timer->read());
+    TEST_ASSERT_EQUAL_INT32(1, p_timer->read_ms());
+    TEST_ASSERT_EQUAL_INT32(1000, p_timer->read_us());
+    TEST_ASSERT_EQUAL_UINT64(1000, p_timer->read_high_resolution_us());
+
+    /* Simulate that 100 us has elapsed between stop and start. */
+    curr_ticker_ticks_val = 1300;
+
+    /* Start the timer. */
+    p_timer->start();
+
+    /* -- Simulate that current time is equal to 125300 us -- */
+    curr_ticker_ticks_val = 125300;
+
+    /* Stop the timer. */
+    p_timer->stop();
+
+    /* Check results - 125 ms have elapsed. */
+    TEST_ASSERT_EQUAL_FLOAT(0.125000f, p_timer->read());
+    TEST_ASSERT_EQUAL_INT32(125, p_timer->read_ms());
+    TEST_ASSERT_EQUAL_INT32(125000, p_timer->read_us());
+    TEST_ASSERT_EQUAL_UINT64(125000, p_timer->read_high_resolution_us());
+
+    /* Simulate that 100 us has elapsed between stop and start. */
+    curr_ticker_ticks_val = 125400;
+
+    /* Start the timer. */
+    p_timer->start();
+
+    /* -- Simulate that current time is equal to 1000400 us -- */
+    curr_ticker_ticks_val = 1000400;
+
+    /* Stop the timer. */
+    p_timer->stop();
+
+    /* Check results - 1 s has elapsed. */
+    TEST_ASSERT_EQUAL_FLOAT(1.000000f, p_timer->read());
+    TEST_ASSERT_EQUAL_INT32(1000, p_timer->read_ms());
+    TEST_ASSERT_EQUAL_INT32(1000000, p_timer->read_us());
+    TEST_ASSERT_EQUAL_UINT64(1000000, p_timer->read_high_resolution_us());
+
+    /* Simulate that 100 us has elapsed between stop and start. */
+    curr_ticker_ticks_val = 1000500;
+
+    /* Start the timer. */
+    p_timer->start();
+
+    /* -- Simulate that current time is equal to 125000500 us -- */
+    curr_ticker_ticks_val = 125000500;
+
+    /* Stop the timer. */
+    p_timer->stop();
+
+    /* Check results - 125 s have elapsed. */
+    TEST_ASSERT_EQUAL_FLOAT(125.000000f, p_timer->read());
+    TEST_ASSERT_EQUAL_INT32(125000, p_timer->read_ms());
+    TEST_ASSERT_EQUAL_INT32(125000000, p_timer->read_us());
+    TEST_ASSERT_EQUAL_UINT64(125000000, p_timer->read_high_resolution_us());
+
+    /* Simulate that 100 us has elapsed between stop and start. */
+    curr_ticker_ticks_val = 125000600;
+
+    /* Start the timer. */
+    p_timer->start();
+
+    /* -- Simulate that current time is equal to MAX_INT_32 us + 600 us (delays
+     *    between stops and starts) -- */
+
+    /* Note that ticker is based on unsigned 32-bit int microsecond counters
+     * while timers are based on 32-bit signed int microsecond counters,
+     * so timers can only count up to a maximum of 2^31-1 microseconds i.e.
+     * 2147483647 us (about 35 minutes). */
+    curr_ticker_ticks_val = 2147484247;
+
+    /* Stop the timer. */
+    p_timer->stop();
+
+    /* Check results - 2147483647 (MAX_INT_32) us have elapsed. */
+    TEST_ASSERT_EQUAL_FLOAT(2147.483647f, p_timer->read());
+    TEST_ASSERT_EQUAL_INT32(2147483, p_timer->read_ms());
+    TEST_ASSERT_EQUAL_INT32(2147483647, p_timer->read_us());
+    TEST_ASSERT_EQUAL_UINT64(2147483647, p_timer->read_high_resolution_us());
+}
+
+/* This test verifies if read(), read_us(), read_ms(),
+ * read_high_resolution_us()
+ * functions return time accumulated between
+ * timer starts and stops.
+ *
+ * Note this function assumes that Timer uses os ticker.
+ *
+ * Given Timer has been successfully created and
+ * few times started and stopped after a specified period of time.
+ * When timer read request is performed.
+ * Then read functions return accumulated time elapsed between starts
+ * and stops.
+ */
+void test_timer_time_accumulation_os_ticker()
+{
+    /* Start the timer. */
+    p_timer->start();
+
+    /* Wait 10 ms. */
+    busy_wait_ms(10);
+
+    /* Stop the timer. */
+    p_timer->stop();
+
+    /* Check results - totally 10 ms have elapsed. */
+    TEST_ASSERT_FLOAT_WITHIN(DELTA_S(10), 0.010f, p_timer->read());
+    TEST_ASSERT_INT32_WITHIN(DELTA_MS(10), 10, p_timer->read_ms());
+    TEST_ASSERT_INT32_WITHIN(DELTA_US(10), 10000, p_timer->read_us());
+    TEST_ASSERT_UINT64_WITHIN(DELTA_US(10), 10000, p_timer->read_high_resolution_us());
+
+    /* Wait 50 ms - this is done to show that time elapsed when
+     * the timer is stopped does not have influence on the
+     * timer counted time. */
+    busy_wait_ms(50);
+
+    /* ------ */
+
+    /* Start the timer. */
+    p_timer->start();
+
+    /* Wait 20 ms. */
+    busy_wait_ms(20);
+
+    /* Stop the timer. */
+    p_timer->stop();
+
+    /* Check results - totally 30 ms have elapsed. */
+    TEST_ASSERT_FLOAT_WITHIN(DELTA_S(30), 0.030f, p_timer->read());
+    TEST_ASSERT_INT32_WITHIN(DELTA_MS(30), 30, p_timer->read_ms());
+    TEST_ASSERT_INT32_WITHIN(DELTA_US(30), 30000, p_timer->read_us());
+    TEST_ASSERT_UINT64_WITHIN(DELTA_US(30), 30000, p_timer->read_high_resolution_us());
+
+    /* Wait 50 ms - this is done to show that time elapsed when
+     * the timer is stopped does not have influence on the
+     * timer counted time. */
+
+    /* ------ */
+
+    /* Start the timer. */
+    p_timer->start();
+
+    /* Wait 30 ms. */
+    busy_wait_ms(30);
+
+    /* Stop the timer. */
+    p_timer->stop();
+
+    /* Check results - totally 60 ms have elapsed. */
+    TEST_ASSERT_FLOAT_WITHIN(DELTA_S(60), 0.060f, p_timer->read());
+    TEST_ASSERT_INT32_WITHIN(DELTA_MS(60), 60, p_timer->read_ms());
+    TEST_ASSERT_INT32_WITHIN(DELTA_US(60), 60000, p_timer->read_us());
+    TEST_ASSERT_UINT64_WITHIN(DELTA_US(60), 60000, p_timer->read_high_resolution_us());
+
+    /* Wait 50 ms - this is done to show that time elapsed when
+     * the timer is stopped does not have influence on the
+     * timer time. */
+    busy_wait_ms(50);
+
+    /* ------ */
+
+    /* Start the timer. */
+    p_timer->start();
+
+    /* Wait 1 sec. */
+    busy_wait_ms(1000);
+
+    /* Stop the timer. */
+    p_timer->stop();
+
+    /* Check results - totally 1060 ms have elapsed. */
+    TEST_ASSERT_FLOAT_WITHIN(DELTA_S(1060), 1.060f, p_timer->read());
+    TEST_ASSERT_INT32_WITHIN(DELTA_MS(1060), 1060, p_timer->read_ms());
+    TEST_ASSERT_INT32_WITHIN(DELTA_US(1060), 1060000, p_timer->read_us());
+    TEST_ASSERT_UINT64_WITHIN(DELTA_US(1060), 1060000, p_timer->read_high_resolution_us());
+}
+
+/* This test verifies if reset() function resets the timer
+ * counted time.
+ *
+ * Note this function assumes that Timer uses os ticker.
+ *
+ * Given timer has been started and stopped once, then reset
+ * operation was performed.
+ * When timer is started and stopped next time.
+ * Then timer read functions returns only the the second
+ * measured time.
+ */
+void test_timer_reset_os_ticker()
+{
+    /* First measure 10 ms delay. */
+    p_timer->start();
+
+    /* Wait 10 ms. */
+    busy_wait_ms(10);
+
+    /* Stop the timer. */
+    p_timer->stop();
+
+    /* Check results - totally 10 ms elapsed. */
+    TEST_ASSERT_FLOAT_WITHIN(DELTA_S(10), 0.010f, p_timer->read());
+    TEST_ASSERT_INT32_WITHIN(DELTA_MS(10), 10, p_timer->read_ms());
+    TEST_ASSERT_INT32_WITHIN(DELTA_US(10), 10000, p_timer->read_us());
+    TEST_ASSERT_UINT64_WITHIN(DELTA_US(10), 10000, p_timer->read_high_resolution_us());
+
+    /* Reset the timer - previous measured time should be lost now. */
+    p_timer->reset();
+
+    /* Now measure 20 ms delay. */
+    p_timer->start();
+
+    /* Wait 20 ms. */
+    busy_wait_ms(20);
+
+    /* Stop the timer. */
+    p_timer->stop();
+
+    /* Check results - 20 ms elapsed since the reset. */
+    TEST_ASSERT_FLOAT_WITHIN(DELTA_S(20), 0.020f, p_timer->read());
+    TEST_ASSERT_INT32_WITHIN(DELTA_MS(20), 20, p_timer->read_ms());
+    TEST_ASSERT_INT32_WITHIN(DELTA_US(20), 20000, p_timer->read_us());
+    TEST_ASSERT_UINT64_WITHIN(DELTA_US(20), 20000, p_timer->read_high_resolution_us());
+}
+
+/* This test verifies if reset() function resets the timer
+ * counted time.
+ *
+ * Note this function assumes that Timer uses user ticker.
+ *
+ * Given timer has been started and stopped once, then reset
+ * operation was performed.
+ * When timer is started and stopped next time.
+ * Then timer read functions returns only the the second
+ * measured time.
+ */
+void test_timer_reset_user_ticker()
+{
+    /* For timer which is using user ticker simulate set current
+     * time (irrelevant in case of os ticker). */
+    curr_ticker_ticks_val = 0;
+
+    /* First measure 10 ms delay. */
+    p_timer->start();
+
+    /* Simulate that 10 ms have elapsed. */
+    curr_ticker_ticks_val = 10000;
+
+    /* Stop the timer. */
+    p_timer->stop();
+
+    /* Check results - totally 10 ms elapsed. */
+    TEST_ASSERT_EQUAL_FLOAT(0.010f, p_timer->read());
+    TEST_ASSERT_EQUAL_INT32(10, p_timer->read_ms());
+    TEST_ASSERT_EQUAL_INT32(10000, p_timer->read_us());
+    TEST_ASSERT_EQUAL_UINT64(10000, p_timer->read_high_resolution_us());
+
+    /* Reset the timer - previous measured time should be lost now. */
+    p_timer->reset();
+
+    /* Now measure 20 ms delay. */
+    p_timer->start();
+
+    /* Simulate that 20 ms have elapsed. */
+    curr_ticker_ticks_val = 30000;
+
+    /* Stop the timer. */
+    p_timer->stop();
+
+    /* Check results - 20 ms elapsed since the reset. */
+    TEST_ASSERT_EQUAL_FLOAT(0.020f, p_timer->read());
+    TEST_ASSERT_EQUAL_INT32(20, p_timer->read_ms());
+    TEST_ASSERT_EQUAL_INT32(20000, p_timer->read_us());
+    TEST_ASSERT_EQUAL_UINT64(20000, p_timer->read_high_resolution_us());
+}
+
+/* This test verifies if calling start() for already
+ * started timer does nothing.
+ *
+ * Note this function assumes that Timer uses os ticker.
+ *
+ * Given timer is already started.
+ * When timer is started again.
+ * Then second start operation is ignored.
+ */
+void test_timer_start_started_timer_os_ticker()
+{
+    /* Start the timer. */
+    p_timer->start();
+
+    /* Wait 10 ms. */
+    busy_wait_ms(10);
+
+    /* Now start timer again. */
+    p_timer->start();
+
+    /* Wait 20 ms. */
+    busy_wait_ms(20);
+
+    /* Stop the timer. */
+    p_timer->stop();
+
+    /* Check results - 30 ms have elapsed since the first start. */
+    TEST_ASSERT_FLOAT_WITHIN(DELTA_S(30), 0.030f, p_timer->read());
+    TEST_ASSERT_INT32_WITHIN(DELTA_MS(30), 30, p_timer->read_ms());
+    TEST_ASSERT_INT32_WITHIN(DELTA_US(30), 30000, p_timer->read_us());
+    TEST_ASSERT_UINT64_WITHIN(DELTA_US(30), 30000, p_timer->read_high_resolution_us());
+}
+
+/* This test verifies if calling start() for already
+ * started timer does nothing.
+ *
+ * Note this function assumes that Timer uses user ticker.
+ *
+ * Given timer is already started.
+ * When timer is started again.
+ * Then second start operation is ignored.
+ */
+void test_timer_start_started_timer_user_ticker()
+{
+    /* For timer which is using user ticker set current
+     * time (irrelevant in case of os ticker). */
+    curr_ticker_ticks_val = 0;
+
+    /* Start the timer. */
+    p_timer->start();
+
+    /* Simulate that 10 ms have elapsed. */
+    curr_ticker_ticks_val = 10000;
+
+    /* Now start timer again. */
+    p_timer->start();
+
+    /* Simulate that 20 ms have elapsed. */
+    curr_ticker_ticks_val = 30000;
+
+    /* Stop the timer. */
+    p_timer->stop();
+
+    /* Check results - 30 ms have elapsed since the first start. */
+    TEST_ASSERT_FLOAT_WITHIN(DELTA_S(30), 0.030f, p_timer->read());
+    TEST_ASSERT_INT32_WITHIN(DELTA_MS(30), 30, p_timer->read_ms());
+    TEST_ASSERT_INT32_WITHIN(DELTA_US(30), 30000, p_timer->read_us());
+    TEST_ASSERT_UINT64_WITHIN(DELTA_US(30), 30000, p_timer->read_high_resolution_us());
+}
+
+/* This test verifies Timer float operator.
+ *
+ * Note this function assumes that Timer uses os ticker.
+ *
+ * Given timer is created and a time period time is counted.
+ * When timer object is casted on float type.
+ * Then counted type in seconds is returned by means of
+ * read() function.
+ */
+void test_timer_float_operator_os_ticker()
+{
+    /* Start the timer. */
+    p_timer->start();
+
+    /* Wait 10 ms. */
+    busy_wait_ms(10);
+
+    /* Stop the timer. */
+    p_timer->stop();
+
+    /* Check result - 10 ms elapsed. */
+    TEST_ASSERT_FLOAT_WITHIN(DELTA_S(10), 0.010f, (float)(*p_timer));
+}
+
+/* This test verifies Timer float operator.
+ *
+ * Note this function assumes that Timer uses user ticker.
+ *
+ * Given timer is created and a time period time is counted.
+ * When timer object is casted on float type.
+ * Then counted type in seconds is returned by means of
+ * read() function.
+ */
+void test_timer_float_operator_user_ticker()
+{
+    /* For timer which is using user ticker set current
+     * time (irrelevant in case of os ticker). */
+    curr_ticker_ticks_val = 0;
+
+    /* Start the timer. */
+    p_timer->start();
+
+    /* Simulate that 10 ms have elapsed. */
+    curr_ticker_ticks_val = 10000;
+
+    /* Stop the timer. */
+    p_timer->stop();
+
+    /* Check result - 10 ms elapsed. */
+    TEST_ASSERT_EQUAL_FLOAT(0.010f, (float)(*p_timer));
+}
+
+/* This test verifies if time counted by the timer is
+ * valid.
+ *
+ * For this test Timer which uses os ticker
+ * must be used.
+ *
+ * Given timer is created.
+ * When timer is used to measure 1ms/10ms/100ms/1s
+ * delays.
+ * Then the results are valid (within acceptable range).
+ */
+template<int wait_val_us>
+void test_timer_time_measurement()
+{
+    /* Start the timer. */
+    p_timer->start();
+
+    /* Wait <wait_val_us> us. */
+    busy_wait_us(wait_val_us);
+
+    /* Stop the timer. */
+    p_timer->stop();
+
+    /* Check results. */
+    TEST_ASSERT_FLOAT_WITHIN(DELTA_S(wait_val_us / US_PER_MSEC), (float)wait_val_us / US_PER_SEC, p_timer->read());
+    TEST_ASSERT_INT32_WITHIN(DELTA_MS(wait_val_us / US_PER_MSEC), wait_val_us / US_PER_MSEC, p_timer->read_ms());
+    TEST_ASSERT_INT32_WITHIN(DELTA_US(wait_val_us / US_PER_MSEC), wait_val_us, p_timer->read_us());
+    TEST_ASSERT_UINT64_WITHIN(DELTA_US(wait_val_us / US_PER_MSEC), wait_val_us, p_timer->read_high_resolution_us());
+}
+
+utest::v1::status_t test_setup(const size_t number_of_cases)
+{
+    GREENTEA_SETUP(15, "default_auto");
+    return verbose_test_setup_handler(number_of_cases);
+}
+
+Case cases[] = {
+    Case("Test: Timer (based on os ticker) is stopped after creation.", timer_os_ticker_setup_handler, test_timer_creation_os_ticker, cleanup_handler),
+    Case("Test: Timer (based on user ticker) is stopped after creation.", timer_user_ticker_setup_handler, test_timer_creation_user_ticker, cleanup_handler),
+
+    Case("Test: Timer (based on os ticker) - measured time accumulation.", timer_os_ticker_setup_handler, test_timer_time_accumulation_os_ticker, cleanup_handler),
+    Case("Test: Timer (based on user ticker) measured time accumulation.", timer_user_ticker_setup_handler, test_timer_time_accumulation_user_ticker, cleanup_handler),
+
+    Case("Test: Timer (based on os ticker) - reset.", timer_os_ticker_setup_handler, test_timer_reset_os_ticker, cleanup_handler),
+    Case("Test: Timer (based on user ticker) - reset.", timer_user_ticker_setup_handler, test_timer_reset_user_ticker, cleanup_handler),
+
+    Case("Test: Timer (based on os ticker) - start started timer.", timer_os_ticker_setup_handler, test_timer_start_started_timer_os_ticker, cleanup_handler),
+    Case("Test: Timer (based on user ticker) - start started timer.", timer_user_ticker_setup_handler, test_timer_start_started_timer_user_ticker, cleanup_handler),
+
+    Case("Test: Timer (based on os ticker) - float operator.", timer_os_ticker_setup_handler, test_timer_float_operator_os_ticker, cleanup_handler),
+    Case("Test: Timer (based on user ticker) - float operator.", timer_user_ticker_setup_handler, test_timer_float_operator_user_ticker, cleanup_handler),
+
+    Case("Test: Timer - time measurement 1 ms.", timer_os_ticker_setup_handler, test_timer_time_measurement<1000>, cleanup_handler),
+    Case("Test: Timer - time measurement 10 ms.", timer_os_ticker_setup_handler, test_timer_time_measurement<10000>, cleanup_handler),
+    Case("Test: Timer - time measurement 100 ms.", timer_os_ticker_setup_handler, test_timer_time_measurement<100000>, cleanup_handler),
+    Case("Test: Timer - time measurement 1 s.", timer_os_ticker_setup_handler, test_timer_time_measurement<1000000>, cleanup_handler),
+};
+
+Specification specification(test_setup, cases);
+
+int main()
+{
+    return !Harness::run(specification);
+}
+