From 71a44a828405d186e1ca1790372c7e41da92466e Mon Sep 17 00:00:00 2001
From: kbracher <k.bracher@fasttube.de>
Date: Fri, 6 Jun 2025 18:29:21 +0200
Subject: [PATCH] track PC, PSR across WWDG resets

---
 AMS_Master_Code/Core/Inc/main.h         |  6 +++++-
 AMS_Master_Code/Core/Src/main.c         | 13 +++++++++++++
 AMS_Master_Code/Core/Src/stm32h7xx_it.c |  9 ++++++---
 AMS_Master_Code/STM32H7A3XX_FLASH.ld    |  7 +++++++
 4 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/AMS_Master_Code/Core/Inc/main.h b/AMS_Master_Code/Core/Inc/main.h
index dc8eb58..626c76e 100644
--- a/AMS_Master_Code/Core/Inc/main.h
+++ b/AMS_Master_Code/Core/Inc/main.h
@@ -50,6 +50,10 @@ extern int pos_air_closed;
 extern int precharge_closed;
 extern int pre_and_air_open;
 
+extern volatile uint32_t wwdg_flag;
+extern volatile uint32_t wwdg_pc; // PC at the time of WWDG interrupt
+extern volatile uint32_t wwdg_psr; // PSR at the time of WWDG interrupt
+
 /* USER CODE END EC */
 
 /* Exported macro ------------------------------------------------------------*/
@@ -123,7 +127,7 @@ void Error_Handler(void);
 #define WAKE2_GPIO_Port GPIOB
 
 /* USER CODE BEGIN Private defines */
-
+#define WWDG_TRIGGERED_FLAG 0xDEADCAFE // Flag to indicate WWDG was triggered
 /* USER CODE END Private defines */
 
 #ifdef __cplusplus
diff --git a/AMS_Master_Code/Core/Src/main.c b/AMS_Master_Code/Core/Src/main.c
index bc0c967..028baad 100644
--- a/AMS_Master_Code/Core/Src/main.c
+++ b/AMS_Master_Code/Core/Src/main.c
@@ -82,6 +82,15 @@ int pos_air_closed;
 int precharge_closed;
 int pre_and_air_open; // used to be:int precharge_opened = 0; now we read if PC is open from the pin -> high if open
 
+/* Variables for WWDG interrupt handling */
+[[gnu::section(".noinit")]] // keep these variables in .noinit section to preserve their values across resets
+volatile uint32_t wwdg_flag; // Flag to indicate WWDG was triggered
+[[gnu::section(".noinit")]]
+volatile uint32_t wwdg_pc; // PC at the time of WWDG interrupt
+[[gnu::section(".noinit")]]
+volatile uint32_t wwdg_psr; // PSR at the time of WWDG interrupt
+
+
 /* USER CODE END PV */
 
 /* Private function prototypes -----------------------------------------------*/
@@ -220,7 +229,11 @@ int main(void)
   debug_log(LOG_LEVEL_INFO, "Starting BMS...");
   if (wdg_reset) {
     debug_log(LOG_LEVEL_WARNING, "Last reset was caused by watchdog!");
+    if (wwdg_flag == WWDG_TRIGGERED_FLAG) {
+      debug_log(LOG_LEVEL_WARNING, "WWDG was triggered! PC: 0x%08lX, PSR: 0x%08lX", wwdg_pc, wwdg_psr);
+    }
   }
+  wwdg_flag = 0; // clear the flag
 
   auto ret = battery_init(&hspi1);
   while (ret != HAL_OK) { //TODO: properly handle reapeated initialization failure
diff --git a/AMS_Master_Code/Core/Src/stm32h7xx_it.c b/AMS_Master_Code/Core/Src/stm32h7xx_it.c
index c5b1f78..c94661d 100644
--- a/AMS_Master_Code/Core/Src/stm32h7xx_it.c
+++ b/AMS_Master_Code/Core/Src/stm32h7xx_it.c
@@ -22,6 +22,7 @@
 #include "stm32h7xx_it.h"
 /* Private includes ----------------------------------------------------------*/
 /* USER CODE BEGIN Includes */
+#include "cmsis_gcc.h"
 #include "log.h"
 /* USER CODE END Includes */
 
@@ -208,9 +209,11 @@ void WWDG_IRQHandler(void)
   /* USER CODE BEGIN WWDG_IRQn 0 */
   // Grab PC from the stack to log it
   uint32_t *stack_pointer = (uint32_t *)__get_MSP();
-  uint32_t prev_pc = stack_pointer[6];  // PC is the 7th word in the stack frame
-  uint32_t prev_psr = stack_pointer[7]; // PSR is the 8th word in the stack frame
-  log_fatal("Watchdog triggered! PC: 0x%08lX, PSR: 0x%08lX", prev_pc, prev_psr);
+  wwdg_pc = stack_pointer[6];  // PC is the 7th word in the stack frame
+  wwdg_psr = stack_pointer[7]; // PSR is the 8th word in the stack frame
+  wwdg_flag = WWDG_TRIGGERED_FLAG; // Set the flag to indicate WWDG was triggered
+  log_fatal("Watchdog triggered! PC: 0x%08lX, PSR: 0x%08lX", wwdg_pc, wwdg_psr);
+  __DSB(); // Ensure ram is written to before entering the handler
   /* USER CODE END WWDG_IRQn 0 */
   HAL_WWDG_IRQHandler(&hwwdg1);
   /* USER CODE BEGIN WWDG_IRQn 1 */
diff --git a/AMS_Master_Code/STM32H7A3XX_FLASH.ld b/AMS_Master_Code/STM32H7A3XX_FLASH.ld
index 2b39280..77cfacd 100644
--- a/AMS_Master_Code/STM32H7A3XX_FLASH.ld
+++ b/AMS_Master_Code/STM32H7A3XX_FLASH.ld
@@ -183,6 +183,13 @@ SECTIONS
     __bss_end__ = _ebss;
   } >DTCMRAM
 
+  /* Keep some data across soft resets */
+  . = ALIGN(4);
+  .no_init : 
+  {
+    *(.no_init)
+  } >DTCMRAM
+
   /* User_heap_stack section, used to check that there is enough RAM left */
   ._user_heap_stack :
   {