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-rw-r--r--lib/stm32/common/rtc_common_bcd.c78
1 files changed, 78 insertions, 0 deletions
diff --git a/lib/stm32/common/rtc_common_bcd.c b/lib/stm32/common/rtc_common_bcd.c
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+/** @addtogroup rtc_file */
+
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2012 Karl Palsson <karlp@tweak.net.au>
+ *
+ * This library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/**@{*/
+
+#include <libopencm3/stm32/rtc.h>
+
+/*---------------------------------------------------------------------------*/
+/** @brief Set RTC prescalars.
+
+This sets the RTC synchronous and asynchronous prescalars.
+*/
+
+void rtc_set_prescaler(u32 sync, u32 async) {
+ /*
+ * Even if only one of the two fields needs to be changed,
+ * 2 separate write accesses must be performed to the RTC_PRER register.
+ */
+ RTC_PRER = (sync & RTC_PRER_PREDIV_S_MASK);
+ RTC_PRER |= (async << RTC_PRER_PREDIV_A_SHIFT);
+}
+
+/*---------------------------------------------------------------------------*/
+/** @brief Wait for RTC registers to be synchronised with the APB1 bus
+
+ Time and Date are accessed through shadow registers which must be synchronized
+*/
+
+void rtc_wait_for_synchro(void) {
+ /* Unlock RTC registers */
+ RTC_WPR = 0xca;
+ RTC_WPR = 0x53;
+
+ RTC_ISR &= ~(RTC_ISR_RSF);
+
+ while (!(RTC_ISR & RTC_ISR_RSF)) {
+ ;
+ }
+ /* disable write protection again */
+ RTC_WPR = 0xff;
+}
+
+/*---------------------------------------------------------------------------*/
+/** @brief Unlock write access to the RTC registers
+
+*/
+void rtc_unlock(void) {
+ RTC_WPR = 0xca;
+ RTC_WPR = 0x53;
+}
+
+/*---------------------------------------------------------------------------*/
+/** @brief Lock write access to the RTC registers
+
+*/
+void rtc_lock(void) {
+ RTC_WPR = 0xff;
+}
+
+/**@}*/