diff --git a/src/W800_SDK_v1.00.10/include/driver/wm_pmu.h b/src/W800_SDK_v1.00.10/include/driver/wm_pmu.h
index d18707f..f31b1a2 100644
--- a/src/W800_SDK_v1.00.10/include/driver/wm_pmu.h
+++ b/src/W800_SDK_v1.00.10/include/driver/wm_pmu.h
@@ -148,14 +148,14 @@ void tls_pmu_clk_select(u8 bypass);
 
 /** NOT PART OF THE OFFICIAL SDK **/
 /**
- * @brief           Starts the internal 32K oscillator calibration cycle.
+ * @brief  Starts the internal 32K oscillator calibration cycle using the PMU's calibration circuit.
  * 
- * @param           None
+ * @param  None
  * 
- * @return          None
+ * @return true if successful, false otherwise
  * 
  */
-void tls_pmu_clk_calibrate(void);
+bool tls_pmu_32k_calibrate(void);
 /**********************************/
 
 
diff --git a/src/W800_SDK_v1.00.10/platform/drivers/pmu/wm_pmu.c b/src/W800_SDK_v1.00.10/platform/drivers/pmu/wm_pmu.c
index e0e4792..5bf43de 100644
--- a/src/W800_SDK_v1.00.10/platform/drivers/pmu/wm_pmu.c
+++ b/src/W800_SDK_v1.00.10/platform/drivers/pmu/wm_pmu.c
@@ -188,6 +188,34 @@ void tls_pmu_clk_select(u8 bypass)
 	tls_reg_write32(HR_PMU_PS_CR, val);	
 }
 
+/** NOT PART OF THE OFFICIAL SDK **/
+bool tls_pmu_32k_calibrate(void)
+{
+    /* To start the calibration procedure, the bit 3 needs to be set to 0 and then to 1 */
+    unsigned int pmu_ps_cr = tls_reg_read32(HR_PMU_PS_CR);
+
+    /* First make sure the bit 3 is 0 */
+    if((pmu_ps_cr & BIT(3)) != 0)
+    {
+        pmu_ps_cr &= ~(BIT(3));
+        tls_reg_write32(HR_PMU_PS_CR, pmu_ps_cr);
+    }
+
+    pmu_ps_cr = tls_reg_read32(HR_PMU_PS_CR);
+    if((pmu_ps_cr & BIT(3)) == 0)
+    {
+        /* Then flip it to one */
+        pmu_ps_cr |= BIT(3);
+        tls_reg_write32(HR_PMU_PS_CR, pmu_ps_cr);
+    }
+    else
+    {
+        return false;
+    }
+
+    return true;
+}
+/**********************************/
 
 /**
  * @brief          	This function is used to start pmu timer0
diff --git a/src/W800_SDK_v1.00.10/platform/drivers/rtc/wm_rtc.c b/src/W800_SDK_v1.00.10/platform/drivers/rtc/wm_rtc.c
index 6411e06..e55e758 100644
--- a/src/W800_SDK_v1.00.10/platform/drivers/rtc/wm_rtc.c
+++ b/src/W800_SDK_v1.00.10/platform/drivers/rtc/wm_rtc.c
@@ -84,12 +84,14 @@ void tls_get_rtc(struct tm *tblock)
 	tblock->tm_sec  =  ctrl1 & 0x0000003f;
 }
 
+/** NOT PART OF THE OFFICIAL SDK **/
 bool tls_is_rtc_running(void)
 {
     int ctrl2 = tls_reg_read32(HR_PMU_RTC_CTRL2);
     
     return ctrl2 & (1 << 16) ? true : false;
 }
+/**********************************/
 
 void PMU_RTC_IRQHandler(void)
 {