diff --git a/STM32F4/cores/maple/libmaple/bkp.c b/STM32F4/cores/maple/libmaple/bkp.c
deleted file mode 120000
index 4717f14..0000000
--- a/STM32F4/cores/maple/libmaple/bkp.c
+++ /dev/null
@@ -1 +0,0 @@
-bkp.c.xxx
\ No newline at end of file
diff --git a/STM32F4/cores/maple/libmaple/bkp.c b/STM32F4/cores/maple/libmaple/bkp.c
new file mode 100644
index 0000000..7d1ad7f
--- /dev/null
+++ b/STM32F4/cores/maple/libmaple/bkp.c
@@ -0,0 +1,129 @@
+/******************************************************************************
+ * The MIT License
+ *
+ * Copyright (c) 2010 LeafLabs, LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *****************************************************************************/
+
+/**
+ * @file bkp.c
+ * @brief Backup register support.
+ */
+
+#include "bkp.h"
+#include "pwr.h"
+#include "rcc.h"
+#include "bitband.h"
+
+static inline __io uint32* data_register(uint8 reg);
+
+bkp_dev bkp = {
+    .regs = BKP_BASE,
+};
+/** Backup device. */
+const bkp_dev *BKP = &bkp;
+
+/**
+ * @brief Initialize backup interface.
+ *
+ * Enables the power and backup interface clocks, and resets the
+ * backup device.
+ */
+void bkp_init(void) {
+    /* Don't call pwr_init(), or you'll reset the device.  We just
+     * need the clock. */
+    rcc_clk_enable(RCC_PWR);
+    rcc_clk_enable(RCC_BKP);
+    rcc_reset_dev(RCC_BKP);
+}
+
+/**
+ * Enable write access to the backup registers.  Backup interface must
+ * be initialized for subsequent register writes to work.
+ * @see bkp_init()
+ */
+void bkp_enable_writes(void) {
+    *bb_perip(&PWR_BASE->CR, PWR_CR_DBP) = 1;
+}
+
+/**
+ * Disable write access to the backup registers.
+ */
+void bkp_disable_writes(void) {
+    *bb_perip(&PWR_BASE->CR, PWR_CR_DBP) = 0;
+}
+
+/**
+ * Read a value from given backup data register.
+ * @param reg Data register to read, from 1 to BKP_NR_DATA_REGS (10 on
+ *            medium-density devices, 42 on high-density devices).
+ */
+uint16 bkp_read(uint8 reg) {
+    __io uint32* dr = data_register(reg);
+    if (!dr) {
+        ASSERT(0);                  /* nonexistent register */
+        return 0;
+    }
+    return (uint16)*dr;
+}
+
+/**
+ * @brief Write a value to given data register.
+ *
+ * Write access to backup registers must be enabled.
+ *
+ * @param reg Data register to write, from 1 to BKP_NR_DATA_REGS (10
+ *            on medium-density devices, 42 on high-density devices).
+ * @param val Value to write into the register.
+ * @see bkp_enable_writes()
+ */
+void bkp_write(uint8 reg, uint16 val) {
+    __io uint32* dr = data_register(reg);
+    if (!dr) {
+        ASSERT(0);                  /* nonexistent register */
+        return;
+    }
+    *dr = (uint32)val;
+}
+
+/*
+ * Data register memory layout is not contiguous. It's split up from
+ * 1--NR_LOW_DRS, beginning at BKP_BASE->DR1, through to
+ * (NR_LOW_DRS+1)--BKP_NR_DATA_REGS, beginning at BKP_BASE->DR11.
+ */
+#define NR_LOW_DRS 10
+
+static inline __io uint32* data_register(uint8 reg) {
+    if (reg < 1 || reg > BKP_NR_DATA_REGS) {
+        return 0;
+    }
+
+#if BKP_NR_DATA_REGS == NR_LOW_DRS
+    return (uint32*)BKP_BASE + reg;
+#else
+    if (reg <= NR_LOW_DRS) {
+        return (uint32*)BKP_BASE + reg;
+    } else {
+        return (uint32*)&(BKP_BASE->DR11) + (reg - NR_LOW_DRS - 1);
+    }
+#endif
+}
diff --git a/STM32F4/cores/maple/libmaple/bkp.h b/STM32F4/cores/maple/libmaple/bkp.h
deleted file mode 120000
index 1dd62bd..0000000
--- a/STM32F4/cores/maple/libmaple/bkp.h
+++ /dev/null
@@ -1 +0,0 @@
-bkp.h.xxx
\ No newline at end of file
diff --git a/STM32F4/cores/maple/libmaple/bkp.h b/STM32F4/cores/maple/libmaple/bkp.h
new file mode 100644
index 0000000..a81267d
--- /dev/null
+++ b/STM32F4/cores/maple/libmaple/bkp.h
@@ -0,0 +1,166 @@
+/******************************************************************************
+ * The MIT License
+ *
+ * Copyright (c) 2010 LeafLabs, LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *****************************************************************************/
+
+/**
+ * @file bkp.h
+ * @brief Backup register support.
+ */
+
+#ifndef _BKP_H_
+#define _BKP_H_
+
+#include "libmaple.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#if defined(STM32_MEDIUM_DENSITY)
+#define BKP_NR_DATA_REGS 10
+#elif defined(STM32_HIGH_DENSITY)
+#define BKP_NR_DATA_REGS 42
+#endif
+
+/** Backup peripheral register map type. */
+typedef struct bkp_reg_map {
+    const uint32 RESERVED1;     ///< Reserved
+    __io uint32 DR1;            ///< Data register 1
+    __io uint32 DR2;            ///< Data register 2
+    __io uint32 DR3;            ///< Data register 3
+    __io uint32 DR4;            ///< Data register 4
+    __io uint32 DR5;            ///< Data register 5
+    __io uint32 DR6;            ///< Data register 6
+    __io uint32 DR7;            ///< Data register 7
+    __io uint32 DR8;            ///< Data register 8
+    __io uint32 DR9;            ///< Data register 9
+    __io uint32 DR10;           ///< Data register 10
+    __io uint32 RTCCR;          ///< RTC control register
+    __io uint32 CR;             ///< Control register
+    __io uint32 CSR;            ///< Control and status register
+#ifdef STM32_HIGH_DENSITY
+    const uint32 RESERVED2;     ///< Reserved
+    const uint32 RESERVED3;     ///< Reserved
+    __io uint32 DR11;           ///< Data register 11
+    __io uint32 DR12;           ///< Data register 12
+    __io uint32 DR13;           ///< Data register 13
+    __io uint32 DR14;           ///< Data register 14
+    __io uint32 DR15;           ///< Data register 15
+    __io uint32 DR16;           ///< Data register 16
+    __io uint32 DR17;           ///< Data register 17
+    __io uint32 DR18;           ///< Data register 18
+    __io uint32 DR19;           ///< Data register 19
+    __io uint32 DR20;           ///< Data register 20
+    __io uint32 DR21;           ///< Data register 21
+    __io uint32 DR22;           ///< Data register 22
+    __io uint32 DR23;           ///< Data register 23
+    __io uint32 DR24;           ///< Data register 24
+    __io uint32 DR25;           ///< Data register 25
+    __io uint32 DR26;           ///< Data register 26
+    __io uint32 DR27;           ///< Data register 27
+    __io uint32 DR28;           ///< Data register 28
+    __io uint32 DR29;           ///< Data register 29
+    __io uint32 DR30;           ///< Data register 30
+    __io uint32 DR31;           ///< Data register 31
+    __io uint32 DR32;           ///< Data register 32
+    __io uint32 DR33;           ///< Data register 33
+    __io uint32 DR34;           ///< Data register 34
+    __io uint32 DR35;           ///< Data register 35
+    __io uint32 DR36;           ///< Data register 36
+    __io uint32 DR37;           ///< Data register 37
+    __io uint32 DR38;           ///< Data register 38
+    __io uint32 DR39;           ///< Data register 39
+    __io uint32 DR40;           ///< Data register 40
+    __io uint32 DR41;           ///< Data register 41
+    __io uint32 DR42;           ///< Data register 42
+#endif
+} bkp_reg_map;
+
+/** Backup peripheral register map base pointer. */
+#define BKP_BASE                        ((struct bkp_reg_map*)0x40006C00)
+
+/** Backup peripheral device type. */
+typedef struct bkp_dev {
+    bkp_reg_map *regs; /**< Register map */
+} bkp_dev;
+
+extern const bkp_dev *BKP;
+
+/*
+ * Register bit definitions
+ */
+
+/* Data Registers */
+
+#define BKP_DR_D                        0xFFFF
+
+/* RTC Clock Calibration Register */
+
+#define BKP_RTCCR_ASOS_BIT              9
+#define BKP_RTCCR_ASOE_BIT              8
+#define BKP_RTCCR_CCO_BIT               7
+
+#define BKP_RTCCR_ASOS                  BIT(BKP_RTCCR_ASOS_BIT)
+#define BKP_RTCCR_ASOE                  BIT(BKP_RTCCR_ASOE_BIT)
+#define BKP_RTCCR_CCO                   BIT(BKP_RTCCR_CCO_BIT)
+#define BKP_RTCCR_CAL                   0x7F
+
+/* Backup control register */
+
+#define BKP_CR_TPAL_BIT                 1
+#define BKP_CR_TPE_BIT                  0
+
+#define BKP_CR_TPAL                     BIT(BKP_CR_TPAL_BIT)
+#define BKP_CR_TPE                      BIT(BKP_CR_TPE_BIT)
+
+/* Backup control/status register */
+
+#define BKP_CSR_TIF_BIT                 9
+#define BKP_CSR_TEF_BIT                 8
+#define BKP_CSR_TPIE_BIT                2
+#define BKP_CSR_CTI_BIT                 1
+#define BKP_CSR_CTE_BIT                 0
+
+#define BKP_CSR_TIF                     BIT(BKP_CSR_TIF_BIT)
+#define BKP_CSR_TEF                     BIT(BKP_CSR_TEF_BIT)
+#define BKP_CSR_TPIE                    BIT(BKP_CSR_TPIE_BIT)
+#define BKP_CSR_CTI                     BIT(BKP_CSR_CTI_BIT)
+#define BKP_CSR_CTE                     BIT(BKP_CSR_CTE_BIT)
+
+/*
+ * Convenience functions
+ */
+
+void bkp_init(void);
+void bkp_enable_writes(void);
+void bkp_disable_writes(void);
+uint16 bkp_read(uint8 reg);
+void bkp_write(uint8 reg, uint16 val);
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif