diff --git a/simplelink/ble_sdk_2_02_02_25/src/examples/simple_peripheral/cc26xx/app/headstage/impedance_meter.h b/simplelink/ble_sdk_2_02_02_25/src/examples/simple_peripheral/cc26xx/app/headstage/impedance_meter.h
index 6d770aeaf..9a35a987a 100644
--- a/simplelink/ble_sdk_2_02_02_25/src/examples/simple_peripheral/cc26xx/app/headstage/impedance_meter.h
+++ b/simplelink/ble_sdk_2_02_02_25/src/examples/simple_peripheral/cc26xx/app/headstage/impedance_meter.h
@@ -433,7 +433,7 @@ static void SimpleBLEPeripheral_clockHandler(UArg arg) {
 //        events |= SBP_PERIODIC_EVT;
 
         // Wake up the application.
-        Semaphore_post(semaphore);
+        Semaphore_post(semaphore); // send samaphore to jump out of infinite waiting(simple_peripheral.c line570)
 }
 
 
@@ -850,14 +850,14 @@ static void EliteKeyPress(uint8_t key){
 
     }
     else{
-        if(OriginEliteFxn == INSTRUCTION.eliteFxn){
+        if(OriginEliteFxn == INSTRUCTION.eliteFxn){ //old function == currunt instruction
             if(ShutDownCounter != 0){
                 // dark LED
                 WorkModeLED();
                 ShutDownCounter = 0;
             }
         }
-        else{
+        else{                                       //old function != currunt instruction
             OriginEliteFxn = INSTRUCTION.eliteFxn;
             if(ShutDownCounter != 0){
                 ShutDownCounter = 0;
diff --git a/simplelink/ble_sdk_2_02_02_25/src/examples/simple_peripheral/cc26xx/app/simple_peripheral.c b/simplelink/ble_sdk_2_02_02_25/src/examples/simple_peripheral/cc26xx/app/simple_peripheral.c
index a2c1cc8f9..2742884fc 100644
--- a/simplelink/ble_sdk_2_02_02_25/src/examples/simple_peripheral/cc26xx/app/simple_peripheral.c
+++ b/simplelink/ble_sdk_2_02_02_25/src/examples/simple_peripheral/cc26xx/app/simple_peripheral.c
@@ -558,8 +558,8 @@ static void SimpleBLEPeripheral_taskFxn(UArg a0, UArg a1) {
     uint8_t counter6994 = 0;
     bool EliteOn = 0;
 
-    Util_constructClock(&periodicClock, SimpleBLEPeripheral_clockHandler, SBP_PERIODIC_EVT_PERIOD, 0, false, SBP_PERIODIC_EVT);
-    Util_startClock(&periodicClock);    // timeup => call SimpleBLEPeripheral_clockHandler
+    Util_constructClock(&periodicClock, SimpleBLEPeripheral_clockHandler, SBP_PERIODIC_EVT_PERIOD, 0, false, SBP_PERIODIC_EVT); //create a clock clockduration = 42(~=0.05 sec)
+    Util_startClock(&periodicClock);    // start the clock, timeup => call SimpleBLEPeripheral_clockHandler => wake up the device
 
     // Application main loops
     for (;;) {
@@ -567,16 +567,16 @@ static void SimpleBLEPeripheral_taskFxn(UArg a0, UArg a1) {
         // Note that the semaphore associated with a thread is signaled when a
         // message is queued to the message receive queue of the thread or when
         // ICall_signal() function is called onto the semaphore.
-        ICall_Errno errno = ICall_wait(ICALL_TIMEOUT_FOREVER);
-        if (errno == ICALL_ERRNO_SUCCESS) {
+        ICall_Errno errno = ICall_wait(ICALL_TIMEOUT_FOREVER); //let errno wait for infinite time, if periodicClock time up then execute below code
+        if (errno == ICALL_ERRNO_SUCCESS) { 
             ICall_EntityID    dest;
             ICall_ServiceEnum src;
             ICall_HciExtEvt * pMsg = NULL;
 
-            if (ICall_fetchServiceMsg(&src, &dest, (void **)&pMsg) == ICALL_ERRNO_SUCCESS) {
+            if (ICall_fetchServiceMsg(&src, &dest, (void **)&pMsg) == ICALL_ERRNO_SUCCESS) { //if successfully retreived a meaasage from who?
                 uint8 safeToDealloc = TRUE;
 
-                if ((src == ICALL_SERVICE_CLASS_BLE) && (dest == selfEntity)) {
+                if ((src == ICALL_SERVICE_CLASS_BLE) && (dest == selfEntity)) {  //src: source id who sent the massage; dest: entity id of the destination of the massage
                     ICall_Stack_Event *pEvt = (ICall_Stack_Event *)pMsg;
 
                     // Check for BLE stack events first
@@ -597,7 +597,7 @@ static void SimpleBLEPeripheral_taskFxn(UArg a0, UArg a1) {
 
             }
 
-            // If RTOS queue is not empty, process app message.
+            // If RTOS queue is not empty, process app message. //RTOS is the OS on Elite
             while (!Queue_empty(appMsgQueue)){
                 sbpEvt_t *pMsg = (sbpEvt_t *)Util_dequeueMsg(appMsgQueue);
                 if (pMsg) {
@@ -610,8 +610,8 @@ static void SimpleBLEPeripheral_taskFxn(UArg a0, UArg a1) {
                 }
             }
 
-            if(!PeriodicEvent){
-                Util_startClock(&periodicClock);
+            if(!PeriodicEvent){  //if there is no periodic event 
+                Util_startClock(&periodicClock); //manually restart the clock
                 key = PIN_getInputValue(switch_on);
                 if(EliteOn){
                     if(counter6994 < 35){
@@ -634,7 +634,7 @@ static void SimpleBLEPeripheral_taskFxn(UArg a0, UArg a1) {
                 }
 
             }
-            else{
+            else{ // if there is periodic event
                 Util_startClock(&periodicClock);
                 if(PeriodicCounter >= StepTime){
                     SimpleBLEPeripheral_performPeriodicTask();