diff --git a/boards/common/nrf51/include/cfg_rtt_default.h b/boards/common/nrf51/include/cfg_rtt_default.h
index 45a15b380a..46ccd3db1c 100644
--- a/boards/common/nrf51/include/cfg_rtt_default.h
+++ b/boards/common/nrf51/include/cfg_rtt_default.h
@@ -29,11 +29,21 @@ extern "C" {
  * @name    Real time counter configuration
  * @{
  */
-#define RTT_DEV             (1)             /* NRF_RTC1 */
-#define RTT_MAX_VALUE       (0x00ffffff)
-#define RTT_FREQUENCY       (1024)
+#ifndef RTT_DEV
+#define RTT_DEV             (1)                 /* NRF_RTC1 */
+#endif
+
+#define RTT_MAX_VALUE       (0x00ffffff)         /* 24bit */
+#define RTT_MAX_FREQUENCY   (32768U)             /* in Hz */
+#define RTT_MIN_FREQUENCY   (8U)                 /* in Hz */
+#define RTT_CLOCK_FREQUENCY (32768U)             /* in Hz, LFCLK*/
+
+#ifndef RTT_FREQUENCY
+#define RTT_FREQUENCY       (1024U)              /* in Hz */
+#endif
 /** @} */
 
+
 #ifdef __cplusplus
 } /* end extern "C" */
 #endif
diff --git a/boards/common/nrf52/include/cfg_rtt_default.h b/boards/common/nrf52/include/cfg_rtt_default.h
index f65a6d2e04..6220aa7443 100644
--- a/boards/common/nrf52/include/cfg_rtt_default.h
+++ b/boards/common/nrf52/include/cfg_rtt_default.h
@@ -28,9 +28,18 @@ extern "C" {
  * @name    Real time counter configuration
  * @{
  */
-#define RTT_DEV             (1)             /* NRF_RTC1 */
-#define RTT_MAX_VALUE       (0x00ffffff)
-#define RTT_FREQUENCY       (1024)
+#ifndef RTT_DEV
+#define RTT_DEV             (1)                 /* NRF_RTC1 */
+#endif
+
+#define RTT_MAX_VALUE       (0x00ffffff)         /* 24bit */
+#define RTT_MAX_FREQUENCY   (32768U)             /* in Hz */
+#define RTT_MIN_FREQUENCY   (8U)                 /* in Hz */
+#define RTT_CLOCK_FREQUENCY (32768U)             /* in Hz, LFCLK*/
+
+#ifndef RTT_FREQUENCY
+#define RTT_FREQUENCY       (1024U)              /* in Hz */
+#endif
 /** @} */
 
 #ifdef __cplusplus
diff --git a/cpu/nrf5x_common/periph/rtt.c b/cpu/nrf5x_common/periph/rtt.c
index c14a4f8d6d..36b113d91c 100644
--- a/cpu/nrf5x_common/periph/rtt.c
+++ b/cpu/nrf5x_common/periph/rtt.c
@@ -38,8 +38,6 @@
 #error "RTT configuration: invalid or no RTC device specified (RTT_DEV)"
 #endif
 
-#define LFCLK_FREQ      (32768U)
-
 /* allocate memory for callbacks and their args */
 static rtt_cb_t alarm_cb;
 static void *alarm_arg;
@@ -59,7 +57,7 @@ void rtt_init(void)
     /* configure interrupt */
     NVIC_EnableIRQ(IRQn);
     /* set prescaler */
-    DEV->PRESCALER = (LFCLK_FREQ / RTT_FREQUENCY) - 1;
+    DEV->PRESCALER = (RTT_CLOCK_FREQUENCY / RTT_FREQUENCY) - 1;
     /* start the actual RTT thing */
     DEV->TASKS_START = 1;
 }