diff --git a/Makefile.dep b/Makefile.dep
index 9037185244a42030926fee4ed64a7b99495b7313..2c320dbdda38b07d91d8590a4cd560fbedbc1105 100644
--- a/Makefile.dep
+++ b/Makefile.dep
@@ -580,6 +580,10 @@ ifneq (,$(filter phydat,$(USEMODULE)))
USEMODULE += fmt
endif
+ifneq (,$(filter evtimer,$(USEMODULE)))
+ USEMODULE += xtimer
+endif
+
ifneq (,$(filter random,$(USEMODULE)))
# select default prng
ifeq (,$(filter prng_%,$(USEMODULE)))
diff --git a/sys/evtimer/Makefile b/sys/evtimer/Makefile
new file mode 100644
index 0000000000000000000000000000000000000000..48422e909a47d7cd428d10fa73825060ccc8d8c2
--- /dev/null
+++ b/sys/evtimer/Makefile
@@ -0,0 +1 @@
+include $(RIOTBASE)/Makefile.base
diff --git a/sys/evtimer/evtimer.c b/sys/evtimer/evtimer.c
new file mode 100644
index 0000000000000000000000000000000000000000..4adfd426370326dca83bc67ebe42a97a472126fb
--- /dev/null
+++ b/sys/evtimer/evtimer.c
@@ -0,0 +1,205 @@
+/*
+ * Copyright (C) 2016-17 Kaspar Schleiser <kaspar@schleiser.de>
+ * 2017 Freie Universität Berlin
+ *
+ * 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 sys_evtimer
+ * @{
+ *
+ * @file
+ * @brief event timer implementation
+ *
+ * @author Kaspar Schleiser <kaspar@schleiser.de>
+ * @author Martine Lenders <m.lenders@fu-berlin.de>
+ *
+ * @}
+ */
+
+#include "div.h"
+#include "irq.h"
+#include "xtimer.h"
+
+#include "evtimer.h"
+
+#define ENABLE_DEBUG (0)
+#include "debug.h"
+
+/* XXX this function is intentionally non-static, since the optimizer can't
+ * handle the pointer hack in this function */
+void evtimer_add_event_to_list(evtimer_t *evtimer, evtimer_event_t *event)
+{
+ uint32_t delta_sum = 0;
+
+ /* we want list->next to point to the first list element. thus we take the
+ * *address* of evtimer->events, then cast it from (evtimer_event_t **) to
+ * (evtimer_event_t*). After that, list->next actually equals
+ * evtimer->events. */
+ evtimer_event_t *list = (evtimer_event_t *)&evtimer->events;
+
+ while (list->next) {
+ evtimer_event_t *list_entry = list->next;
+ if ((list_entry->offset + delta_sum) > event->offset) {
+ break;
+ }
+ delta_sum += list_entry->offset;
+ list = list->next;
+ }
+
+ event->next = list->next;
+ if (list->next) {
+ evtimer_event_t *next_entry = list->next;
+ next_entry->offset += delta_sum;
+ next_entry->offset -= event->offset;
+ }
+ event->offset -= delta_sum;
+
+ list->next = event;
+}
+
+static void _del_event_from_list(evtimer_t *evtimer, evtimer_event_t *event)
+{
+ evtimer_event_t *list = (evtimer_event_t *) &evtimer->events;
+
+ while (list->next) {
+ evtimer_event_t *list_entry = list->next;
+ if (list_entry == event) {
+ list->next = event->next;
+ if (list->next) {
+ list_entry = list->next;
+ list_entry->offset += event->offset;
+ }
+ break;
+ }
+ list = list->next;
+ }
+}
+
+static void _set_timer(xtimer_t *timer, uint32_t offset)
+{
+ uint64_t offset_in_us = (uint64_t)offset * 1000;
+
+ DEBUG("evtimer: now=%" PRIu32 " setting xtimer to %" PRIu32 ":%" PRIu32 "\n",
+ xtimer_now_usec(), (uint32_t)(offset_in_us >> 32),
+ (uint32_t)(offset_in_us));
+ _xtimer_set64(timer, offset_in_us, offset_in_us >> 32);
+}
+
+static void _update_timer(evtimer_t *evtimer)
+{
+ if (evtimer->events) {
+ evtimer_event_t *event = evtimer->events;
+ _set_timer(&evtimer->timer, event->offset);
+ }
+ else {
+ xtimer_remove(&evtimer->timer);
+ }
+}
+
+static uint32_t _get_offset(xtimer_t *timer)
+{
+ uint64_t now = xtimer_now_usec64();
+ uint64_t target = ((uint64_t)timer->long_target) << 32 | timer->target;
+
+ if (target <= now) {
+ return 0;
+ }
+ else {
+ target -= now;
+ /* add half of 125 so integer division rounds to nearest */
+ return div_u64_by_125((target >> 3) + 62);
+ }
+}
+
+static void _update_head_offset(evtimer_t *evtimer)
+{
+ if (evtimer->events) {
+ evtimer_event_t *event = evtimer->events;
+ event->offset = _get_offset(&evtimer->timer);
+ DEBUG("evtimer: _update_head_offset(): new head offset %" PRIu32 "\n", event->offset);
+ }
+}
+
+void evtimer_add(evtimer_t *evtimer, evtimer_event_t *event)
+{
+ unsigned state = irq_disable();
+
+ DEBUG("evtimer_add(): adding event with offset %" PRIu32 "\n", event->offset);
+
+ _update_head_offset(evtimer);
+ evtimer_add_event_to_list(evtimer, event);
+ if (evtimer->events == event) {
+ _set_timer(&evtimer->timer, event->offset);
+ }
+ irq_restore(state);
+ if (sched_context_switch_request) {
+ thread_yield_higher();
+ }
+}
+
+void evtimer_del(evtimer_t *evtimer, evtimer_event_t *event)
+{
+ unsigned state = irq_disable();
+
+ DEBUG("evtimer_del(): removing event with offset %" PRIu32 "\n", event->offset);
+
+ _update_head_offset(evtimer);
+ _del_event_from_list(evtimer, event);
+ _update_timer(evtimer);
+ irq_restore(state);
+}
+
+static evtimer_event_t *_get_next(evtimer_t *evtimer)
+{
+ evtimer_event_t *event = evtimer->events;
+
+ if (event && (event->offset == 0)) {
+ evtimer->events = event->next;
+ return event;
+ }
+ else {
+ return NULL;
+ }
+}
+
+static void _evtimer_handler(void *arg)
+{
+ DEBUG("_evtimer_handler()\n");
+
+ evtimer_t *evtimer = (evtimer_t *)arg;
+
+ /* this function gets called directly by xtimer if the set xtimer expired.
+ * Thus the offset of the first event is down to zero. */
+ evtimer_event_t *event = evtimer->events;
+ event->offset = 0;
+
+ /* iterate the event list */
+ while ((event = _get_next(evtimer))) {
+ evtimer->callback(event);
+ }
+
+ _update_timer(evtimer);
+}
+
+void evtimer_init(evtimer_t *evtimer, evtimer_callback_t handler)
+{
+ evtimer->callback = handler;
+ evtimer->timer.callback = _evtimer_handler;
+ evtimer->timer.arg = (void *)evtimer;
+ evtimer->events = NULL;
+}
+
+void evtimer_print(const evtimer_t *evtimer)
+{
+ evtimer_event_t *list = evtimer->events;
+
+ while (list->next) {
+ evtimer_event_t *list_entry = list->next;
+ printf("ev offset=%u\n", (unsigned)list_entry->offset);
+ list = list->next;
+ }
+}
diff --git a/sys/include/evtimer.h b/sys/include/evtimer.h
new file mode 100644
index 0000000000000000000000000000000000000000..da8dc9a1efca7b461bfd6aecf3e8d07fa1a19253
--- /dev/null
+++ b/sys/include/evtimer.h
@@ -0,0 +1,113 @@
+/*
+ * Copyright (C) 2016-17 Kaspar Schleiser <kaspar@schleiser.de>
+ * 2017 Freie Universität Berlin
+ *
+ * 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.
+ */
+
+/**
+ * @defgroup sys_evtimer Millisecond interval event timers
+ * @ingroup sys
+ * @brief Provides timers for events up to @$2^{32}@$ milliseconds in the
+ * future
+ *
+ * @note Experimental and likely to replaced with unified timer API
+ *
+ * RIOT's main timer subsystem is @ref sys_xtimer "xtimer", but for many
+ * applications @ref sys_xtimer "xtimer's" 64-bit absolute time values are
+ * wasteful or clumsy to use.
+ *
+ * Compared to @ref sys_xtimer "xtimer", evtimer offers:
+ *
+ * - only relative 32-bit millisecond timer values
+ * Events can be scheduled with a relative offset of up to ~49.7 days in the
+ * future.
+ * **For time-critical stuff, use @ref sys_xtimer "xtimer"!**
+ * - more flexible, "intrusive" timer type @ref evtimer_event_t only contains
+ * the necessary fields, which can be extended as needed, and handlers define
+ * actions taken on timer triggers. Check out @ref evtimer_msg_event_t as
+ * example.
+ * - uses @ref sys_xtimer "xtimer" as backend
+ *
+ * @{
+ *
+ * @file
+ * @brief evtimer API definitions
+ *
+ * @author Kaspar Schleiser <kaspar@schleiser.de>
+ * @author Martine Lenders <m.lenders@fu-berlin.de>
+ */
+
+#ifndef EVTIMER_H
+#define EVTIMER_H
+
+#include <stdint.h>
+
+#include "xtimer.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Generic event
+ */
+typedef struct evtimer_event {
+ struct evtimer_event *next; /**< the next event in the queue */
+ uint32_t offset; /**< offset in milliseconds from previous event */
+} evtimer_event_t;
+
+/**
+ * @brief Event timer callback type
+ */
+typedef void(*evtimer_callback_t)(evtimer_event_t* event);
+
+/**
+ * @brief Event timer
+ */
+typedef struct {
+ xtimer_t timer; /**< Timer */
+ evtimer_callback_t callback; /**< Handler function for this evtimer's
+ event type */
+ evtimer_event_t *events; /**< Event queue */
+} evtimer_t;
+
+/**
+ * @brief Initializes an event timer
+ *
+ * @param[in] evtimer An event timer
+ * @param[in] handler An event handler function
+ */
+void evtimer_init(evtimer_t *evtimer, evtimer_callback_t handler);
+
+/**
+ * @brief Adds event to an event timer
+ *
+ * @param[in] evtimer An event timer
+ * @param[in] event An event
+ */
+void evtimer_add(evtimer_t *evtimer, evtimer_event_t *event);
+
+/**
+ * @brief Removes an event from an event timer
+ *
+ * @param[in] evtimer An event timer
+ * @param[in] event An event
+ */
+void evtimer_del(evtimer_t *evtimer, evtimer_event_t *event);
+
+/**
+ * @brief Print overview of current state of an event timer
+ *
+ * @param[in] evtimer An event timer
+ */
+void evtimer_print(const evtimer_t *evtimer);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* EVTIMER_H */
+/** @} */
diff --git a/sys/include/evtimer_msg.h b/sys/include/evtimer_msg.h
new file mode 100644
index 0000000000000000000000000000000000000000..ce15f6c3c65a0a0ab2f79a14bb2e87203ce5f7b9
--- /dev/null
+++ b/sys/include/evtimer_msg.h
@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2016-17 Kaspar Schleiser <kaspar@schleiser.de>
+ * 2017 Freie Universität Berlin
+ *
+ * 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.
+ */
+
+/**
+ * @addtogroup sys_evtimer
+ * @{
+ *
+ * @file
+ * @brief IPC-based evtimer definitions
+ *
+ * @author Kaspar Schleiser <kaspar@schleiser.de>
+ * @author Martine Lenders <m.lenders@fu-berlin.de>
+ */
+#ifndef EVTIMER_MSG_H
+#define EVTIMER_MSG_H
+
+#include "msg.h"
+#include "evtimer.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief IPC-message event timer
+ * @extends evtimer_t
+ */
+typedef evtimer_t evtimer_msg_t;
+
+/**
+ * @brief IPC-message event
+ * @extends evtimer_event_t
+ */
+typedef struct {
+ evtimer_event_t event; /**< base class */
+ msg_t msg; /**< the IPC message to generate on event */
+} evtimer_msg_event_t;
+
+/**
+ * @brief Adds event to an event timer that handles events via IPC
+ *
+ * @param[in] evtimer An event timer
+ * @param[in] event An event
+ * @param[in] target_pid The PID of the thread that should receive the IPC
+ * message
+ */
+static inline void evtimer_add_msg(evtimer_msg_t *evtimer,
+ evtimer_msg_event_t *event,
+ kernel_pid_t target_pid)
+{
+ /* use sender_pid field to get target_pid into callback function */
+ event->msg.sender_pid = target_pid;
+ evtimer_add(evtimer, &event->event);
+}
+
+/**
+ * @brief Event handler for IPC messages
+ *
+ * @param[in] event The event to handle
+ */
+static inline void _evtimer_msg_handler(evtimer_event_t *event)
+{
+ evtimer_msg_event_t *mevent = (evtimer_msg_event_t *)event;
+ msg_send_int(&mevent->msg, mevent->msg.sender_pid);
+}
+
+/**
+ * @brief Initializes event timer to handle events via IPC
+ *
+ * @param[in] evtimer An event timer
+ */
+static inline void evtimer_init_msg(evtimer_t *evtimer)
+{
+ evtimer_init(evtimer, _evtimer_msg_handler);
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* EVTIMER_MSG_H */
+/** @} */