Diff: Device/WakeUp_Freescale.cpp

Revision:

18:13aed323e040

Parent:

16:f3adba7cf7c4

Child:

19:9d355da2770e

--- a/Device/WakeUp_Freescale.cpp	Wed Apr 22 20:36:13 2015 +0000
+++ b/Device/WakeUp_Freescale.cpp	Wed Jul 01 19:28:55 2015 +0000
@@ -10,6 +10,12 @@
 static uint32_t oldvector;
 static uint8_t oldPSR;
 
+//See if we have a 32kHz crystal on the clock input
+//Check if the DMX32 bit is set, not perfect, but most cases will work
+static inline bool is32kXtal(void) {
+    return (MCG->C4 & MCG_C4_DMX32_MASK);
+}
+
 void restore(void);
 
 void WakeUp::set_ms(uint32_t ms)
@@ -35,15 +41,23 @@
     LPTMR0->CSR = 0;
 
     if (ms != 0) {
-        //Clock from the 1kHz LPO
-        LPTMR0->PSR = LPTMR_PSR_PCS(1);
-
         /* Set interrupt handler */
         NVIC_SetVector(LPTimer_IRQn, (uint32_t)WakeUp::irq_handler);
         NVIC_EnableIRQ(LPTimer_IRQn);
         
-        uint32_t counts = (uint32_t)((float)ms * cycles_per_ms);
-
+        uint32_t counts;
+        //Set clock
+        if (is32kXtal()) {
+            SIM->SOPT1 &= ~SIM_SOPT1_OSC32KSEL_MASK;    //Put RTC/LPTMR on 32kHz external. 
+            OSC0->CR |= OSC_CR_EREFSTEN_MASK;
+            LPTMR0->PSR = LPTMR_PSR_PCS(2);
+            counts = (uint32_t)((float)ms * 32.768f);
+        } else {
+            //Clock from the 1kHz LPO
+            LPTMR0->PSR = LPTMR_PSR_PCS(1);
+            counts = (uint32_t)((float)ms * cycles_per_ms);
+        }
+        
         //If no prescaler is needed
         if (counts <= 0xFFFF) 
             LPTMR0->PSR |= LPTMR_PSR_PBYP_MASK;
@@ -77,16 +91,18 @@
 
 void WakeUp::calibrate(void)
 {
-    wait_us(1);     //Otherwise next wait might overwrite our settings
-    cycles_per_ms = 1.0;
-    set_ms(1100);
-    wait_ms(100);
-
-    //Write first to sync value
-    LPTMR0->CNR = 0;
-    uint32_t ticks = LPTMR0->CNR;
-    cycles_per_ms = ticks / 100.0;
-    set_ms(0);
+    if (!is32kXtal()) {
+        wait_us(1);     //Otherwise next wait might overwrite our settings
+        cycles_per_ms = 1.0;
+        set_ms(1100);
+        wait_ms(100);
+    
+        //Write first to sync value
+        LPTMR0->CNR = 0;
+        uint32_t ticks = LPTMR0->CNR;
+        cycles_per_ms = ticks / 100.0;
+        set_ms(0);
+    }
 }
 
 void restore(void){