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-rw-r--r--libmaple/iwdg.c41
-rw-r--r--libmaple/iwdg.h85
2 files changed, 88 insertions, 38 deletions
diff --git a/libmaple/iwdg.c b/libmaple/iwdg.c
index 82a0151..3d67ee8 100644
--- a/libmaple/iwdg.c
+++ b/libmaple/iwdg.c
@@ -23,34 +23,37 @@
*****************************************************************************/
/**
- * @file iwdg.c
- *
- * @brief Independent watchdog support
+ * @file iwdg.c
+ * @brief Independent watchdog (IWDG) support
*/
-#include "libmaple.h"
#include "iwdg.h"
-#define IWDG_UNLOCK 0x5555
-#define IWDG_START 0xCCCC
-#define IWDG_FEED 0xAAAA
-
/**
- * @brief Initialise and start the watchdog
+ * @brief Initialise and start the watchdog
+ *
+ * The prescaler and reload set the timeout. A prescaler of 3 divides
+ * the 40 kHz clock by 32 and gives roughly 1 ms per reload.
*
- * The prescaler and reload set the timeout. A prescaler of 3 divides
- * the 40 kHz clock by 32 and gives roughly 1 ms per reload.
+ * @param prescaler Prescaler for the 40 KHz IWDG clock.
+ * @param reload Independent watchdog counter reload value.
*/
-void iwdg_init(uint8 prescaler, uint16 reload) {
- __write(IWDG_KR, IWDG_UNLOCK);
- __write(IWDG_PR, prescaler);
- __write(IWDG_RLR, reload);
+void iwdg_init(iwdg_prescaler prescaler, uint16 reload) {
+ IWDG_BASE->KR = IWDG_KR_UNLOCK;
+ IWDG_BASE->PR = prescaler;
+ IWDG_BASE->RLR = reload;
- /* Start things off */
- __write(IWDG_KR, IWDG_START);
- __write(IWDG_KR, IWDG_FEED);
+ /* Start things off */
+ IWDG_BASE->KR = IWDG_KR_START;
+ iwdg_feed();
}
+/**
+ * @brief Reset the IWDG counter.
+ *
+ * Calling this function will cause the IWDG counter to be reset to
+ * its reload value.
+ */
void iwdg_feed(void) {
- __write(IWDG_KR, IWDG_FEED);
+ IWDG_BASE->KR = IWDG_KR_FEED;
}
diff --git a/libmaple/iwdg.h b/libmaple/iwdg.h
index 4ab0ddf..81f0fdb 100644
--- a/libmaple/iwdg.h
+++ b/libmaple/iwdg.h
@@ -23,35 +23,82 @@
*****************************************************************************/
/**
- * @file iwdg.h
+ * @file iwdg.h
+ * @author Michael Hope, Marti Bolivar <mbolivar@leaflabs.com>
+ * @brief Independent watchdog support.
*
- * @brief Independent watchdog support
+ * To use the independent watchdog, first call iwdg_init() with the
+ * appropriate prescaler and IWDG counter reload values for your
+ * application. Afterwards, you must periodically call iwdg_feed()
+ * before the IWDG counter reaches 0 to reset the counter to its
+ * reload value. If you do not, the chip will reset.
+ *
+ * Once started, the independent watchdog cannot be turned off.
*/
#ifndef _IWDG_H_
#define _IWDG_H_
+#include "libmaple_types.h"
+
#ifdef __cplusplus
extern "C"{
#endif
-#define IWDG_BASE 0x40003000
-#define IWDG_KR (IWDG_BASE + 0x0)
-#define IWDG_PR (IWDG_BASE + 0x4)
-#define IWDG_RLR (IWDG_BASE + 0x8)
-#define IWDG_SR (IWDG_BASE + 0xC)
-
-enum {
- IWDG_PRE_4,
- IWDG_PRE_8,
- IWDG_PRE_16,
- IWDG_PRE_32,
- IWDG_PRE_64,
- IWDG_PRE_128,
- IWDG_PRE_256
-};
-
-void iwdg_init(uint8 prescaler, uint16 reload);
+/*
+ * Register map
+ */
+
+/** Independent watchdog register map type. */
+typedef struct iwdg_reg_map {
+ __io uint32 KR; /**< Key register. */
+ __io uint32 PR; /**< Prescaler register. */
+ __io uint32 RLR; /**< Reload register. */
+ __io uint32 SR; /**< Status register */
+} iwdg_reg_map;
+
+#define IWDG_BASE ((struct iwdg_reg_map*)0x40003000)
+
+/*
+ * Register bit definitions
+ */
+
+/* Key register */
+
+#define IWDG_KR_UNLOCK 0x5555
+#define IWDG_KR_FEED 0xAAAA
+#define IWDG_KR_START 0xCCCC
+
+/* Prescaler register */
+
+#define IWDG_PR_DIV_4 0x0
+#define IWDG_PR_DIV_8 0x1
+#define IWDG_PR_DIV_16 0x2
+#define IWDG_PR_DIV_32 0x3
+#define IWDG_PR_DIV_64 0x4
+#define IWDG_PR_DIV_128 0x5
+#define IWDG_PR_DIV_256 0x6
+
+/* Status register */
+
+#define IWDG_SR_RVU_BIT 1
+#define IWDG_SR_PVU_BIT 0
+
+#define IWDG_SR_RVU BIT(IWDG_SR_RVU_BIT)
+#define IWDG_SR_PVU BIT(IWDG_SR_PVU_BIT)
+
+/** Independent watchdog prescalers */
+typedef enum {
+ IWDG_PRE_4 = IWDG_PR_DIV_4,
+ IWDG_PRE_8 = IWDG_PR_DIV_8,
+ IWDG_PRE_16 = IWDG_PR_DIV_16,
+ IWDG_PRE_32 = IWDG_PR_DIV_32,
+ IWDG_PRE_64 = IWDG_PR_DIV_64,
+ IWDG_PRE_128 = IWDG_PR_DIV_128,
+ IWDG_PRE_256 = IWDG_PR_DIV_256
+} iwdg_prescaler;
+
+void iwdg_init(iwdg_prescaler prescaler, uint16 reload);
void iwdg_feed(void);
#ifdef __cplusplus