diff --git a/cpu/lpc23xx/periph/rtc.c b/cpu/lpc23xx/periph/rtc.c
index 0820ada8b3..7abf3087d1 100644
--- a/cpu/lpc23xx/periph/rtc.c
+++ b/cpu/lpc23xx/periph/rtc.c
@@ -44,14 +44,14 @@ void RTC_IRQHandler(void) __attribute__((interrupt("IRQ")));
 
 void rtc_init(void)
 {
-    PCONP |= BIT9;
-    RTC_AMR = 0xff;                         /* disable alarm irq */
-    RTC_CIIR = 0;                           /* disable increase irq */
-    RTC_CISS = 0;                           /* disable subsecond irq */
+    PCONP   |= BIT9;
+    RTC_AMR  = 0xff;        /* disable alarm irq */
+    RTC_CIIR = 0;           /* disable increase irq */
+    RTC_CISS = 0;           /* disable subsecond irq */
 
-    INTWAKE |= BIT15;                       /* rtc irq wakes up mcu from power down */
+    INTWAKE |= BIT15;       /* rtc irq wakes up mcu from power down */
 
-    RTC_CCR = CCR_CLKSRC;                   /* Clock from external 32 kHz Osc. */
+    RTC_CCR  = CCR_CLKSRC;  /* Clock from external 32 kHz Osc. */
 
     /* Initialize clock to a a sane and predictable default
      * after cold boot or external reset.
@@ -64,7 +64,7 @@ void rtc_init(void)
     rtc_poweron();
 
     DEBUG("%2lu.%2lu.%4lu  %2lu:%2lu:%2lu\n",
-            RTC_DOM, RTC_MONTH, RTC_YEAR, RTC_HOUR, RTC_MIN, RTC_SEC);
+          RTC_DOM, RTC_MONTH, RTC_YEAR, RTC_HOUR, RTC_MIN, RTC_SEC);
 }
 
 /**
@@ -81,83 +81,83 @@ int rtc_set_time(struct tm *localt)
     rtc_tm_normalize(localt);
 
     /* set clock */
-    RTC_SEC = localt->tm_sec;
-    RTC_MIN = localt->tm_min;
-    RTC_HOUR = localt->tm_hour;
-    RTC_DOM = localt->tm_mday;
-    RTC_DOW = localt->tm_wday;
-    RTC_DOY = localt->tm_yday;
+    RTC_SEC   = localt->tm_sec;
+    RTC_MIN   = localt->tm_min;
+    RTC_HOUR  = localt->tm_hour;
+    RTC_DOM   = localt->tm_mday;
+    RTC_DOW   = localt->tm_wday;
+    RTC_DOY   = localt->tm_yday;
     RTC_MONTH = localt->tm_mon + 1;
-    RTC_YEAR = localt->tm_year;
+    RTC_YEAR  = localt->tm_year;
 
     return 0;
 }
 
 int rtc_get_time(struct tm *localt)
 {
-    if (localt != NULL) {
-        localt->tm_sec = RTC_SEC;
-        localt->tm_min = RTC_MIN;
-        localt->tm_hour = RTC_HOUR;
-        localt->tm_mday = RTC_DOM;
-        localt->tm_wday = RTC_DOW;
-        localt->tm_yday = RTC_DOY;
-        localt->tm_mon = RTC_MONTH - 1;
-        localt->tm_year = RTC_YEAR;
-        localt->tm_isdst = -1; /* not available */
-        return 0;
+    if (localt == NULL) {
+        return -1;
     }
-    return -1;
+
+    localt->tm_sec   = RTC_SEC;
+    localt->tm_min   = RTC_MIN;
+    localt->tm_hour  = RTC_HOUR;
+    localt->tm_mday  = RTC_DOM;
+    localt->tm_wday  = RTC_DOW;
+    localt->tm_yday  = RTC_DOY;
+    localt->tm_mon   = RTC_MONTH - 1;
+    localt->tm_year  = RTC_YEAR;
+    localt->tm_isdst = -1; /* not available */
+
+    return 0;
 }
 
 
 int rtc_set_alarm(struct tm *localt, rtc_alarm_cb_t cb, void *arg)
 {
     if (localt != NULL) {
+
         /* normalize input */
         rtc_tm_normalize(localt);
 
-        RTC_ALSEC = localt->tm_sec;
-        RTC_ALMIN = localt->tm_min;
+        RTC_ALSEC  = localt->tm_sec;
+        RTC_ALMIN  = localt->tm_min;
         RTC_ALHOUR = localt->tm_hour;
-        RTC_ALDOM = localt->tm_mday;
-        RTC_ALDOW = localt->tm_wday;
-        RTC_ALDOY = localt->tm_yday;
-        RTC_ALMON = localt->tm_mon + 1;
+        RTC_ALDOM  = localt->tm_mday;
+        RTC_ALDOW  = localt->tm_wday;
+        RTC_ALDOY  = localt->tm_yday;
+        RTC_ALMON  = localt->tm_mon + 1;
         RTC_ALYEAR = localt->tm_year;
-        RTC_AMR = 0;                                            /* set which alarm fields to check */
+        RTC_AMR    = 0;                 /* set which alarm fields to check */
         DEBUG("alarm set %2lu.%2lu.%4lu  %2lu:%2lu:%2lu\n",
               RTC_ALDOM, RTC_ALMON, RTC_ALYEAR, RTC_ALHOUR, RTC_ALMIN, RTC_ALSEC);
+    }
 
+    if (cb) {
         _cb = cb;
         _cb_arg = arg;
-        return 0;
-    }
-    else if (cb == NULL) {
-        return -1;
     }
 
-    RTC_AMR = 0xff;
-    return -2;
+    return 0;
 }
 
 int rtc_get_alarm(struct tm *localt)
 {
-    if (localt != NULL) {
-        localt->tm_sec = RTC_ALSEC;
-        localt->tm_min = RTC_ALMIN;
-        localt->tm_hour = RTC_ALHOUR;
-        localt->tm_mday = RTC_ALDOM;
-        localt->tm_wday = RTC_ALDOW;
-        localt->tm_yday = RTC_ALDOY;
-        localt->tm_mon = RTC_ALMON - 1;
-        localt->tm_year = RTC_ALYEAR;
-        localt->tm_isdst = -1; /* not available */
-
-        return 0;
+    if (localt == NULL) {
+        return -1;
     }
 
-    return -1;
+    localt->tm_sec   = RTC_ALSEC;
+    localt->tm_min   = RTC_ALMIN;
+    localt->tm_hour  = RTC_ALHOUR;
+    localt->tm_mday  = RTC_ALDOM;
+    localt->tm_wday  = RTC_ALDOW;
+    localt->tm_yday  = RTC_ALDOY;
+    localt->tm_mon   = RTC_ALMON - 1;
+    localt->tm_year  = RTC_ALYEAR;
+    localt->tm_isdst = -1; /* not available */
+
+    return 0;
 }
 
 void rtc_clear_alarm(void)
@@ -167,8 +167,8 @@ void rtc_clear_alarm(void)
 
 void rtc_poweron(void)
 {
-    PCONP |= BIT9;
-    RTC_ILR = (ILR_RTSSF | ILR_RTCCIF | ILR_RTCALF);    /* clear interrupt flags */
+    PCONP   |= BIT9;
+    RTC_ILR  = (ILR_RTSSF | ILR_RTCCIF | ILR_RTCALF);    /* clear interrupt flags */
     RTC_CCR |= CCR_CLKEN;                               /* enable clock */
     install_irq(RTC_INT, &RTC_IRQHandler, IRQP_RTC);    /* install interrupt handler */
 }
@@ -177,20 +177,13 @@ void rtc_poweroff(void)
 {
     RTC_CCR &= ~CCR_CLKEN;  /* disable clock */
     install_irq(RTC_INT, NULL, 0);
-    RTC_ILR = 0;
     PCONP &= ~BIT9;
 }
 
 void RTC_IRQHandler(void)
 {
-    if (RTC_ILR & ILR_RTSSF) {
-        /* sub second interrupt (does not need flag-clearing) */
-    }
-    else if (RTC_ILR & ILR_RTCCIF) {
-        /* counter increase interrupt */
-    }
-    else if (RTC_ILR & ILR_RTCALF) {
-        RTC_ILR |= ILR_RTCALF;
+    if (RTC_ILR & ILR_RTCALF) {
+        RTC_ILR = ILR_RTCALF;
         RTC_AMR = 0xff;                     /* disable alarm irq */
         if (_cb) {
             _cb(_cb_arg);