diff --git a/drivers/include/rtt_rtc.h b/drivers/include/rtt_rtc.h
new file mode 100644
index 0000000000..d68c72a8af
--- /dev/null
+++ b/drivers/include/rtt_rtc.h
@@ -0,0 +1,59 @@
+/*
+ * Copyright (C) 2021 ML!PA Consulting GmbH
+ *
+ * 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    drivers_rtt_rtc     RTC emulation on top of a RTT
+ * @ingroup     drivers_periph_rtc
+ *
+ * @{
+ *
+ * @file
+ * @brief       Additional functions provided in addition to the normal RTC API.
+ *
+ * @author      Benjamin Valentin <benjamin.valentin@ml-pa.com>
+ */
+
+#ifndef RTT_RTC_H
+#define RTT_RTC_H
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Set the time as epoch with sub-second precision
+ *        This feature is an extension provided by the `rtt_rtc` module.
+ *
+ * @note The actual µs precision depends on the underlying hardware.
+ *       The smallest time step will be 1 / @ref RTT_FREQUENCY.
+ *
+ * @param[in] s     The new epoch timestamp
+ * @param[in] us    Sub-Seconds
+ */
+void rtt_rtc_settimeofday(uint32_t s, uint32_t us);
+
+/**
+ * @brief Get the current epoch with sub-second precision
+ *        This feature is an extension provided by the `rtt_rtc` module.
+ *
+ * @note The actual µs precision depends on the underlying hardware.
+ *       The smallest time step will be 1 / @ref RTT_FREQUENCY.
+ *
+ * @param[out] s    The current epoch timestamp
+ * @param[out] us   Sub-Seconds
+ */
+void rtt_rtc_gettimeofday(uint32_t *s, uint32_t *us);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* RTT_RTC_H */
+/** @} */
diff --git a/drivers/rtt_rtc/rtt_rtc.c b/drivers/rtt_rtc/rtt_rtc.c
index 2e16ac69c6..3fb2533ed6 100644
--- a/drivers/rtt_rtc/rtt_rtc.c
+++ b/drivers/rtt_rtc/rtt_rtc.c
@@ -7,7 +7,7 @@
  */
 
 /**
- * @ingroup     drivers_periph_rtc
+ * @ingroup     drivers_rtt_rtc
  * @{
  *
  * @file
@@ -29,6 +29,7 @@
 #include "periph/rtc.h"
 #include "periph/rtt.h"
 #include "timex.h"
+#include "rtt_rtc.h"
 
 #define ENABLE_DEBUG    0
 #include "debug.h"
@@ -204,3 +205,27 @@ void rtc_poweroff(void)
 {
     rtt_poweroff();
 }
+
+void rtt_rtc_settimeofday(uint32_t s, uint32_t us)
+{
+    /* disable alarm to prevent race condition */
+    rtt_clear_alarm();
+    uint32_t now = ((uint64_t)us * RTT_SECOND) / US_PER_SEC;
+    rtc_now      = s;
+    rtt_set_counter(now);
+    /* calculate next wake-up period */
+    _update_alarm(0);
+}
+
+void rtt_rtc_gettimeofday(uint32_t *s, uint32_t *us)
+{
+    uint32_t now;
+    unsigned state = irq_disable();
+
+    now  = rtt_get_counter();
+    *s   = _rtc_now(now);
+    *us  = ((uint64_t)SUBSECONDS(now - last_alarm) * US_PER_SEC)
+         / RTT_SECOND;
+
+    irq_restore(state);
+}