<libmaple/iwdg.h>
¶
Independent Watchdog (IWDG) support. The IWDG peripheral is common across supported targets, so everything documented here is portable.
Usage Note¶
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 zero 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.
Functions¶
-
void
iwdg_init
(iwdg_prescaler prescaler, uint16 reload)¶ Initialise and start the watchdog.
The prescaler and reload set the timeout. For example, a prescaler of IWDG_PRE_32 divides the 40 kHz clock by 32 and gives roughly 1 ms per reload.
- Parameters
prescaler
-Prescaler for the 40 kHz IWDG clock.
reload
-Independent watchdog counter reload value.
-
void
iwdg_feed
(void)¶ Reset the IWDG counter.
Calling this function will cause the IWDG counter to be reset to its reload value.
Types¶
-
enum
iwdg_prescaler
¶ Independent watchdog prescalers.
These divide the 40 kHz IWDG clock.
Values:
-
IWDG_PRE_4
= IWDG_PR_DIV_4¶ Divide by 4.
-
IWDG_PRE_8
= IWDG_PR_DIV_8¶ Divide by 8.
-
IWDG_PRE_16
= IWDG_PR_DIV_16¶ Divide by 16.
-
IWDG_PRE_32
= IWDG_PR_DIV_32¶ Divide by 32.
-
IWDG_PRE_64
= IWDG_PR_DIV_64¶ Divide by 64.
-
IWDG_PRE_128
= IWDG_PR_DIV_128¶ Divide by 128.
-
IWDG_PRE_256
= IWDG_PR_DIV_256¶ Divide by 256.
-
Register Maps¶
-
IWDG_BASE
¶ Independent watchdog base pointer.
-
struct
iwdg_reg_map
¶ Independent watchdog register map type.
Register Bit Definitions¶
These are given as source code.
/* 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 (1U << IWDG_SR_RVU_BIT)
#define IWDG_SR_PVU (1U << IWDG_SR_PVU_BIT)