[NUCLEO_F103RB] Add RTC

Author: bcostm

libraries/mbed/targets/hal/TARGET_STM/TARGET_NUCLEO_F103RB/device.h

@@ -33,7 +33,7 @@
 #define DEVICE_SPI              1
 #define DEVICE_SPISLAVE         0
 
-#define DEVICE_RTC              0
+#define DEVICE_RTC              1
 
 #define DEVICE_PWMOUT           1
 

libraries/mbed/targets/hal/TARGET_STM/TARGET_NUCLEO_F103RB/rtc_api.c

@@ -0,0 +1,65 @@
+/* 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.
+ */
+#include "rtc_api.h"
+
+static int rtc_inited = 0;
+
+void rtc_init(void) {
+    RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR | RCC_APB1Periph_BKP, ENABLE); // Enable PWR and Backup clock
+
+    PWR_BackupAccessCmd(ENABLE); // Allow access to Backup Domain
+  
+    BKP_DeInit(); // Reset Backup Domain
+  
+    // Enable LSE and wait till it's ready
+    RCC_LSEConfig(RCC_LSE_ON);
+    while (RCC_GetFlagStatus(RCC_FLAG_LSERDY) == RESET) {}
+      
+    RCC_RTCCLKConfig(RCC_RTCCLKSource_LSE); // Select LSE as RTC Clock Source
+      
+    RCC_RTCCLKCmd(ENABLE); // Enable RTC Clock 
+      
+    RTC_WaitForSynchro(); // Wait for RTC registers synchronization
+      
+    RTC_WaitForLastTask(); // Wait until last write operation on RTC registers has finished
+
+    // Set RTC period to 1 sec
+    // RTC period = RTCCLK/RTC_PR = (32.768 KHz)/(32767+1)
+    RTC_SetPrescaler(32767);
+    
+    RTC_WaitForLastTask(); // Wait until last write operation on RTC registers has finished
+      
+    rtc_inited = 1;
+}
+
+void rtc_free(void) {
+    RCC_DeInit(); // Resets the RCC clock configuration to the default reset state
+    rtc_inited = 0;
+}
+
+int rtc_isenabled(void) {
+    return rtc_inited;
+}
+
+time_t rtc_read(void) {
+    return (time_t)RTC_GetCounter();
+}
+
+void rtc_write(time_t t) {
+    RTC_WaitForLastTask(); // Wait until last write operation on RTC registers has finished
+    RTC_SetCounter(t); // Change the current time
+    RTC_WaitForLastTask(); // Wait until last write operation on RTC registers has finished
+}