Independent Watchdog. Kicked from main loop.

keirf · Oct 8, 2019 · 9a9bc53 · 9a9bc53
1 parent d42322c
commit 9a9bc53
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Showing 3 changed files with 25 additions and 0 deletions.
diff --git a/inc/stm32f10x.h b/inc/stm32f10x.h
@@ -17,6 +17,7 @@
 #define PWR volatile struct pwr * const
 #define BKP volatile struct bkp * const
 #define RCC volatile struct rcc * const
+#define IWDG volatile struct iwdg * const
 #define GPIO volatile struct gpio * const
 #define AFIO volatile struct afio * const
 #define EXTI volatile struct exti * const
@@ -35,6 +36,7 @@ static FLASH flash = (struct flash *)FLASH_BASE;
 static PWR pwr = (struct pwr *)PWR_BASE;
 static BKP bkp = (struct bkp *)BKP_BASE;
 static RCC rcc = (struct rcc *)RCC_BASE;
+static IWDG iwdg = (struct iwdg *)IWDG_BASE;
 static GPIO gpioa = (struct gpio *)GPIOA_BASE;
 static GPIO gpiob = (struct gpio *)GPIOB_BASE;
 static GPIO gpioc = (struct gpio *)GPIOC_BASE;

diff --git a/inc/stm32f10x_regs.h b/inc/stm32f10x_regs.h
@@ -248,8 +248,21 @@ struct rcc {
 #define RCC_APB2ENR_IOPAEN   (1u<< 2)
 #define RCC_APB2ENR_AFIOEN   (1u<< 0)
 
+#define RCC_CSR_LSIRDY       (1u<< 1)
+#define RCC_CSR_LSION        (1u<< 0)
+
 #define RCC_BASE 0x40021000
 
+/* Independent Watchdog */
+struct iwdg {
+    uint32_t kr;   /* 00: Key */
+    uint32_t pr;   /* 04: Prescaler */
+    uint32_t rlr;  /* 08: Reload */
+    uint32_t sr;   /* 0C: Status */
+};
+
+#define IWDG_BASE 0x40003000
+
 /* General-purpose I/O */
 struct gpio {
     uint32_t crl;  /* 00: Port configuration low */

diff --git a/src/main.c b/src/main.c
@@ -532,6 +532,13 @@ int main(void)
     time_t frame_time;
     bool_t lost_sync, _keyboard_held;
 
+    /* Set up the Watchdog. Based on LSI at 30-60kHz (av. 40kHz). */
+    iwdg->kr = 0xcccc; /* Enables watchdog, turns on LSI oscillator. */
+    iwdg->kr = 0x5555; /* Enables access to PR and RLR. */
+    iwdg->pr = 3;      /* Prescaler: div32 => Ticks at 937-1875Hz (1250Hz) */
+    iwdg->rlr = 400;   /* Reload:    400   => Times out in 213-426ms (320ms) */
+    iwdg->kr = 0xaaaa; /* Load the new Reload value. */
+
     /* Relocate DATA. Initialise BSS. */
     if (_sdat != _ldat)
         memcpy(_sdat, _ldat, _edat-_sdat);
@@ -683,6 +690,9 @@ int main(void)
 
     for (;;) {
 
+        /* Reload the Watchdog. */
+        iwdg->kr = 0xaaaa;
+
         canary_check();
 
         /* Wait while displaying OSD box. This avoids modifying config values