Diff: targets/TARGET_Freescale/TARGET_KLXX/rtc_api.c

Revision:

0:f269e3021894

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/TARGET_Freescale/TARGET_KLXX/rtc_api.c	Sun Oct 23 15:10:02 2016 +0000
@@ -0,0 +1,119 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2013 ARM Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#if DEVICE_RTC
+
+#include "rtc_api.h"
+#include "PeripheralPins.h"
+#include "clk_freqs.h"
+
+static void init(void) {
+    // enable RTC clock
+    SIM->SCGC6 |= SIM_SCGC6_RTC_MASK;
+
+    // select RTC clock source
+    SIM->SOPT1 &= ~SIM_SOPT1_OSC32KSEL_MASK;
+    
+    // Enable external crystal source if clock source is 32KHz
+    if (extosc_frequency()==32768) {
+        SIM->SOPT1 |= SIM_SOPT1_OSC32KSEL(OSC32KCLK);
+    }
+    else{
+        // If main clock is NOT 32KHz crystal, use external 32KHz clock source defined in PeripheralPins.c
+        SIM->SOPT1 |= SIM_SOPT1_OSC32KSEL(PinMap_RTC[0].peripheral);
+        pinmap_pinout(PinMap_RTC[0].pin, PinMap_RTC);        //Map RTC clk input (if not NC)
+    }
+}
+
+void rtc_init(void) {
+    init();
+
+    // Configure the TSR. default value: 1
+    RTC->TSR = 1;
+
+    // Configure Time Compensation Register to calibrate RTC accuracy
+
+    // dissable LRL lock
+    RTC->LR &= ~RTC_LR_LRL_MASK;
+    // RTC->TCR: RTC_TCR_CIR_MASK,RTC_TCR_CIR(x)=0,RTC_TCR_TCR(x)=0  Default no correction
+    RTC->TCR = RTC_TCR_CIR(0) | RTC_TCR_TCR(0);
+    /*
+        RTC_TCR_CIR(x) sets the compensation interval in seconds from 1 to 256.
+        0x05 will apply the compensation once every 4 seconds.
+
+        RTC_TCR_TCR(x) sets the Register Overflow
+        0x80 Time Prescaler Register overflows every 32896 clock cycles. (+128)
+        ... ... RTC runs slower
+        0xFF Time Prescaler Register overflows every 32769 clock cycles.
+        0x00 Time Prescaler Register overflows every 32768 clock cycles, Default.
+        0x01 Time Prescaler Register overflows every 32767 clock cycles.
+        ... ... RTC runs faster
+        0x7F Time Prescaler Register overflows every 32641 clock cycles. (-128)
+    */
+    // enable TCL lock
+    RTC->LR |= RTC_LR_TCL_MASK;
+    // enable LRL lock
+    RTC->LR |= RTC_LR_LRL_MASK;
+
+    // enable counter
+    RTC->SR |= RTC_SR_TCE_MASK;
+}
+
+void rtc_free(void) {
+    // [TODO]
+}
+
+/*
+ * Little check routine to see if the RTC has been enabled
+ * 0 = Disabled, 1 = Enabled
+ */
+int rtc_isenabled(void) {
+    // even if the RTC module is enabled,
+    // as we use RTC_CLKIN and an external clock,
+    // we need to reconfigure the pins. That is why we
+    // call init() if the rtc is enabled
+
+    // if RTC not enabled return 0
+    SIM->SCGC5 |= SIM_SCGC5_PORTA_MASK;
+    SIM->SCGC6 |= SIM_SCGC6_RTC_MASK;
+    if ((RTC->SR & RTC_SR_TCE_MASK) == 0)
+        return 0;
+
+    init();
+    return 1;
+}
+
+time_t rtc_read(void) {
+    return RTC->TSR;
+}
+
+void rtc_write(time_t t) {
+    // disable counter
+    RTC->SR &= ~RTC_SR_TCE_MASK;
+
+    // we do not write 0 into TSR
+    // to avoid invalid time
+    if (t == 0)
+        t = 1;
+
+    // write seconds
+    RTC->TSR = t;
+
+    // re-enable counter
+    RTC->SR |= RTC_SR_TCE_MASK;
+}
+
+#endif