Hardware WDT Stack Dump Tool

libraries/esp8266/examples/HwdtStackDump/AddOn.h

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+void printHelpAddOn(Print& out)__attribute__((weak));
+int hotKeyHandlerAddOn(Print& out, int hotKey)__attribute__((weak));
+void crashMeIfYouCan(void)__attribute__((weak));

libraries/esp8266/examples/HwdtStackDump/AddOn.ino

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+#ifdef HWDT_STACK_DUMP_H
+
+extern struct rst_info resetInfo;
+
+void printHwdtDebugInfo(Print& out) {
+  extern struct rst_info resetInfo;
+  out.println(String(F("RTC_SYS[0] = ")) + (hwdt_info.rtc_sys_reason) + F(", resetInfo.reason = ") + (resetInfo.reason) + F(", ") + ESP.getResetReason());
+  out.println(String(F("ROM API reset reason = ")) + (hwdt_info.rom_api_reason));
+  out.println(String(F("HWDT reset reason = ")) + (hwdt_info.reset_reason));
+  if (REASON_EXT_SYS_RST < hwdt_info.reset_reason) {
+    out.println(String(F("Reset reason confirmation failed!\n")));
+  }
+
+  out.println();
+  if (hwdt_info.sys) {
+    out.println(String(F("Stack Usages:")));
+    out.printf_P(PSTR("  ctx: sys  %6u\r\n"), hwdt_info.sys);
+    uint32 cont_flags = hwdt_info.cont_integrity;
+    out.printf_P(PSTR("  ctx: cont %6u, Integrity Flags: %04X - %s\r\n"), hwdt_info.cont, cont_flags, (cont_flags) ? "fail" : "pass");
+    if (hwdt_info.rom) {
+      out.printf_P(PSTR("  ctx: ROM  %6u\r\n"), hwdt_info.rom);
+    }
+  } else {
+    out.println(F("No stack usage information available at this time. Try restart."));
+  }
+  out.println();
+}
+
+
+void printHelpAddOn(Print& out) {
+  out.println(F("  0    - Divide by zero, exception(0);"));
+  out.println(F("  p    - panic();"));
+  out.println(F("  c    - Hardware WDT reset by calling a missing function."));
+  out.println();
+  out.println(F("Additional options:"));
+  out.println(F("  d    - Print some HWDT Debug info."));
+}
+
+
+
+int hotKeyHandlerAddOn(Print& out, int hotKey) {
+  switch (hotKey) {
+    case 'd':
+      printHwdtDebugInfo(out);
+      break;
+    case 'p':
+      out.println(F("Time to panic()!"));
+      panic();
+      break;
+    case '0':
+      out.println(F("Crashing by dividing by zero."));
+      out.printf_P(PSTR("This should not print %d\n"), divideA_B(1, 0));
+      break;
+    case 'c':
+      out.println(F("Now calling: void crashMeIfYouCan(void)__attribute__((weak));"));
+      out.println(F("This function was missing when the sketch was linked. ..."));
+      crashMeIfYouCan();
+      break;
+    default:
+      return 0;
+  }
+  return 1;
+}
+
+int divideA_B(int a, int b) {
+  return (a / b);
+}
+
+#else
+void printHwdtDebugInfo(Print& out) {
+  (void)out;
+}
+
+int hotKeyHandlerAddOn(Print& out, int hotKey) {
+  (void)out;
+  (void)hotKey;
+  return 0;
+}
+
+void printHelpAddOn(Print& out) {
+  (void)out;
+}
+#endif

libraries/esp8266/examples/HwdtStackDump/HwdtStackDump.ino

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+/*
+   A Hardware WDT Reset stack dump tool by Michael Hightower
+
+   This Sketch demonstrates the use of a tool that prints a stack dump after
+   a Hardware WDT reset. After a Hardware Watchdog Timer reset, the module
+   hwdt_app_entry.cpp writes a stack dump to the serial interface.
+
+   The goal was to have a file (hwdt_app_entry.cpp) that could be dropped into
+   a sketch directory, then open the sketch project, build, upload, and debug.
+
+   When the ESP8266 restarts because of a Hardware WDT reset, the serial port
+   speed defaults to 115200 bps. For support of other speeds, review the
+   comments on option HWDT_UART_SPEED in wdt_app_entry.cpp.
+
+*/
+
+#include <Arduino.h>
+#include <ESP8266WiFi.h>
+#include <Esp.h>
+#include <user_interface.h>
+
+#include "AddOn.h"
+/*
+  If you need to run your sketch w/o this tool or you want to  see the
+  difference with and without this tool. Comment out the #include below. And
+  comment out the "#define DEBUG_HWDT" line in hwdt_app_entry.cpp.
+*/
+#include "hwdt_app_entry.h"
+
+
+void setup(void) {
+#ifdef DEBUG_HWDT
+  enable_debug_hwdt_at_link_time();
+#endif
+  WiFi.persistent(false); // w/o this a flash write occurs at every boot
+  WiFi.mode(WIFI_OFF);
+  Serial.begin(115200);
+  delay(20);
+  Serial.println();
+  Serial.println();
+  Serial.println(F("The Hardware Watchdog Timer Demo is now available for crashing ..."));
+  Serial.println();
+  processKey(Serial, '?');
+}
+
+
+void loop(void) {
+  if (Serial.available() > 0) {
+    int hotKey = Serial.read();
+    processKey(Serial, hotKey);
+  }
+}

libraries/esp8266/examples/HwdtStackDump/ProcessKey.ino

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+#include <esp8266_undocumented.h>
+
+int* nullPointer = NULL;
+
+void processKey(Print& out, int hotKey) {
+  switch (hotKey) {
+    case 'r':
+      out.printf_P(PSTR("Reset, ESP.reset(); ...\r\n"));
+      ESP.reset();
+      break;
+    case 't':
+      out.printf_P(PSTR("Restart, ESP.restart(); ...\r\n"));
+      ESP.restart();
+      break;
+    case 's': {
+        uint32_t startTime = millis();
+        out.printf_P(PSTR("Now crashing with Software WDT. This will take about 3 seconds.\r\n"));
+        ets_install_putc1(ets_putc);
+        while (true) {
+          ets_printf("%9lu\r", (millis() - startTime));
+          ets_delay_us(250000);
+          // stay in an loop blocking other system activity.
+        }
+      }
+      break;
+    case 'h':
+      out.printf_P(PSTR("Now crashing with Hardware WDT. This will take about 6 seconds.\r\n"));
+      // ESP.wdtDisable();
+      asm volatile("" ::: "memory");
+      asm volatile("mov.n a2, %0\n"
+                   "mov.n a3, %1\n"
+                   "mov.n a4, %2\n"
+                   "mov.n a5, %3\n"
+                   "mov.n a6, %4\n"
+                   : : "r"(0xaaaaaaaa), "r"(0xaaaaaaaa), "r"(0xaaaaaaaa), "r"(0xaaaaaaaa), "r"(0xaaaaaaaa));
+      // Could not find these in the stack dump, unless interrupts were enabled.
+      {
+        uint32_t startTime = millis();
+        // Avoid all the Core functions that play nice, so we can hog
+        // the system and crash.
+        ets_install_putc1(ets_putc);
+        xt_rsil(15);
+        while (true) {
+          ets_printf("%9lu\r", (millis() - startTime));
+          ets_delay_us(250000);
+          // stay in an loop blocking other system activity.
+          //
+          // Note:
+          // Hardware WDT kicks in if Software WDT is unable to perform.
+          // With the Hardware WDT, nothing is saved on the stack, that I have seen.
+        }
+      }
+      break;
+    case '\r':
+      out.println();
+    case '\n':
+      break;
+    case '?':
+      out.println();
+      out.println(F("Press a key + <enter>"));
+      out.println(F("  r    - Reset, ESP.reset();"));
+      out.println(F("  t    - Restart, ESP.restart();"));
+      out.println(F("  ?    - Print Help"));
+      out.println();
+      out.println(F("Crash with:"));
+      out.println(F("  s    - Software WDT"));
+      out.println(F("  h    - Hardware WDT"));
+      printHelpAddOn(out);
+      out.println();
+      break;
+    default:
+      if (hotKeyHandlerAddOn(out, hotKey)) {
+        return;
+      }
+      out.printf_P(PSTR("\"%c\" - Not an option?  / ? - help"), hotKey);
+      out.println();
+      processKey(out, '?');
+      break;
+  }
+}