Diff: targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/lp_ticker.c

Revision:

0:9b334a45a8ff

Child:

50:a417edff4437

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/lp_ticker.c	Thu Oct 01 15:25:22 2015 +0300
@@ -0,0 +1,97 @@
+/***************************************************************************//**
+ * @file lp_ticker.c
+ *******************************************************************************
+ * @section License
+ * <b>(C) Copyright 2015 Silicon Labs, http://www.silabs.com</b>
+ *******************************************************************************
+ *
+ * Permission is granted to anyone to use this software for any purpose,
+ * including commercial applications, and to alter it and redistribute it
+ * freely, subject to the following restrictions:
+ *
+ * 1. The origin of this software must not be misrepresented; you must not
+ *    claim that you wrote the original software.
+ * 2. Altered source versions must be plainly marked as such, and must not be
+ *    misrepresented as being the original software.
+ * 3. This notice may not be removed or altered from any source distribution.
+ *
+ * DISCLAIMER OF WARRANTY/LIMITATION OF REMEDIES: Silicon Labs has no
+ * obligation to support this Software. Silicon Labs is providing the
+ * Software "AS IS", with no express or implied warranties of any kind,
+ * including, but not limited to, any implied warranties of merchantability
+ * or fitness for any particular purpose or warranties against infringement
+ * of any proprietary rights of a third party.
+ *
+ * Silicon Labs will not be liable for any consequential, incidental, or
+ * special damages, or any other relief, or for any claim by any third party,
+ * arising from your use of this Software.
+ *
+ ******************************************************************************/
+
+#include "device.h"
+#if DEVICE_LOWPOWERTIMER
+
+#include "rtc_api.h"
+#include "rtc_api_HAL.h"
+#include "lp_ticker_api.h"
+
+void lp_ticker_init()
+{
+    rtc_init_real(RTC_INIT_LPTIMER);
+    rtc_set_comp0_handler((uint32_t)lp_ticker_irq_handler);
+}
+
+void lp_ticker_set_interrupt(timestamp_t timestamp)
+{
+    uint64_t timestamp_ticks;
+    uint64_t current_ticks = RTC_CounterGet();
+    timestamp_t current_time = ((uint64_t)(current_ticks * 1000000) / (LOW_ENERGY_CLOCK_FREQUENCY / RTC_CLOCKDIV_INT));
+
+
+    /* calculate offset value */
+    timestamp_t offset = timestamp - current_time;
+    if(offset > 0xEFFFFFFF) offset = 100;
+
+    /* map offset to RTC value */
+    // ticks = offset * RTC frequency div 1000000
+    timestamp_ticks = ((uint64_t)offset * (LOW_ENERGY_CLOCK_FREQUENCY / RTC_CLOCKDIV_INT)) / 1000000;
+    timestamp_ticks += current_ticks;
+
+    /* RTC has 24 bit resolution */
+    timestamp_ticks &= 0xFFFFFF;
+
+    /* check for RTC limitation */
+    if((timestamp_ticks - RTC_CounterGet()) >= 0x800000) timestamp_ticks = RTC_CounterGet() + 2;
+
+    /* Set callback */
+    RTC_FreezeEnable(true);
+    RTC_CompareSet(0, (uint32_t)timestamp_ticks);
+    RTC_IntEnable(RTC_IF_COMP0);
+    RTC_FreezeEnable(false);
+}
+
+inline void lp_ticker_disable_interrupt()
+{
+    RTC_IntDisable(RTC_IF_COMP0);
+}
+
+inline void lp_ticker_clear_interrupt()
+{
+    RTC_IntClear(RTC_IF_COMP0);
+}
+
+timestamp_t lp_ticker_read()
+{
+    uint64_t ticks_temp;
+    uint64_t ticks = RTC_CounterGet();
+
+    /* ticks = counter tick value
+     * timestamp = value in microseconds
+     * timestamp = ticks * 1.000.000 / RTC frequency
+     */
+
+    ticks_temp = (ticks * 1000000) / (LOW_ENERGY_CLOCK_FREQUENCY / RTC_CLOCKDIV_INT);
+    return (timestamp_t) (ticks_temp & 0xFFFFFFFF);
+}
+
+#endif