diff --git a/drivers/common/opentimers.c b/drivers/common/opentimers.c
index 0c7c6683ce..0a6f1dfeb8 100644
--- a/drivers/common/opentimers.c
+++ b/drivers/common/opentimers.c
@@ -65,8 +65,19 @@ opentimers_id_t opentimers_create(uint8_t timer_id, uint8_t task_prio){
         }
     }
 
+    if (timer_id==TIMER_ISR){
+        for (id = TIMER_TSCH + 1; id < TIMER_NUMBER_NON_GENERAL; id++){
+            if (opentimers_vars.timersBuf[id].isUsed  == FALSE){
+                opentimers_vars.timersBuf[id].isUsed   = TRUE;
+                opentimers_vars.timersBuf[id].timer_task_prio = task_prio;
+                ENABLE_INTERRUPTS();
+                return id;
+            }
+        }
+    }
+
     if (timer_id==TIMER_GENERAL_PURPOSE){
-        for (id=TIMER_NUMBER_NON_GENERAL;id<MAX_NUM_TIMERS;id++){
+        for (id =TIMER_NUMBER_NON_GENERAL;id<MAX_NUM_TIMERS;id++){
             if (opentimers_vars.timersBuf[id].isUsed  == FALSE){
                 opentimers_vars.timersBuf[id].isUsed   = TRUE;
                 opentimers_vars.timersBuf[id].timer_task_prio = task_prio;
@@ -370,11 +381,11 @@ void opentimers_timer_callback(void){
         sctimer_setCompare(sctimer_readCounter()+SPLITE_TIMER_DURATION);
         return;
     } else {
-        if (opentimers_vars.timersBuf[TIMER_INHIBIT].currentCompareValue == opentimers_vars.currentCompareValue){
+        if (opentimers_vars.currentCompareValue == opentimers_vars.timersBuf[TIMER_INHIBIT].currentCompareValue){
             // this is the timer interrupt right after inhibit timer, pre call the non-tsch, non-inhibit timer interrupt here to avoid interrupt during receiving serial bytes
             for (i=0;i<MAX_NUM_TIMERS;i++){
                 if (opentimers_vars.timersBuf[i].isrunning==TRUE){
-                    if (i!=TIMER_TSCH && i!=TIMER_INHIBIT && opentimers_vars.timersBuf[i].currentCompareValue - opentimers_vars.currentCompareValue < PRE_CALL_TIMER_WINDOW){
+                    if (i >= TIMER_NUMBER_NON_GENERAL && opentimers_vars.timersBuf[i].currentCompareValue - opentimers_vars.currentCompareValue < PRE_CALL_TIMER_WINDOW){
                         opentimers_vars.timersBuf[i].currentCompareValue = opentimers_vars.currentCompareValue;
                     }
                 }
@@ -385,7 +396,7 @@ void opentimers_timer_callback(void){
                 if (opentimers_vars.currentCompareValue == opentimers_vars.timersBuf[i].currentCompareValue){
                     // this timer expired, mark as expired
                     opentimers_vars.timersBuf[i].lastCompareValue    = opentimers_vars.timersBuf[i].currentCompareValue;
-                    if (i==TIMER_TSCH){
+                    if (i < TIMER_NUMBER_NON_GENERAL && i != 0 ){
                         opentimers_vars.insideISR = TRUE;
                         opentimers_vars.timersBuf[i].isrunning  = FALSE;
                         opentimers_vars.timersBuf[i].callback(i);
@@ -460,4 +471,4 @@ void opentimers_timer_callback(void){
     } else {
         opentimers_vars.running        = FALSE;
     }
-}
\ No newline at end of file
+}
diff --git a/drivers/common/opentimers.h b/drivers/common/opentimers.h
index 763035e420..fc067adcb0 100644
--- a/drivers/common/opentimers.h
+++ b/drivers/common/opentimers.h
@@ -7,6 +7,7 @@
 #ifndef __OPENTIMERS_H
 #define __OPENTIMERS_H
 
+#include "config.h"
 #include "opendefs.h"
 
 /**
@@ -19,7 +20,7 @@
 //=========================== define ==========================================
 
 /// Maximum number of timers that can run concurrently
-#define MAX_NUM_TIMERS             15
+#define MAX_NUM_TIMERS             (15 + TIMER_ISR_NUMBER)
 #define MAX_TICKS_IN_SINGLE_CLOCK  (uint32_t)(((PORT_TIMER_WIDTH)0xFFFFFFFF)>>1)
 #define ERROR_NO_AVAILABLE_ENTRIES 255
 #define MAX_DURATION_ISR           33 // 33@32768Hz = 1ms
@@ -27,9 +28,9 @@
 
 #define TIMER_INHIBIT              0
 #define TIMER_TSCH                 1
+#define TIMER_ISR                  254
 #define TIMER_GENERAL_PURPOSE      255
-
-#define TIMER_NUMBER_NON_GENERAL   2
+#define TIMER_NUMBER_NON_GENERAL   (2 + TIMER_ISR_NUMBER)
 
 #define SPLITE_TIMER_DURATION     15 // in ticks
 #define PRE_CALL_TIMER_WINDOW     PORT_TsSlotDuration
@@ -98,4 +99,4 @@ bool             opentimers_isRunning(opentimers_id_t id);
 \}
 */
 
-#endif
\ No newline at end of file
+#endif
diff --git a/inc/config.h b/inc/config.h
index 3d483431df..612fdb6b1e 100644
--- a/inc/config.h
+++ b/inc/config.h
@@ -433,6 +433,20 @@
 #define BOARD_FASTSIM_ENABLED (0)
 #endif
 
+// ======================== Driver configuration ========================
+
+
+/**
+ * \def TIMER_ISR_NUMBER
+ *
+ * Number of TIMER_ISR, this does not include TIMER_TSCH or TIMER_INHIBIT
+ *
+ */
+#ifndef TIMER_ISR_NUMBER
+#define TIMER_ISR_NUMBER (0)
+#endif
+
+
 // ======================== Kernel configuration ========================
 
 /**