Implement tmr.wdclr()

components/modules/tmr.c

@@ -233,6 +233,15 @@ static int tmr_create( lua_State *L ) {
 }
 
 
+// Lua: tmr.wdclr()
+static int tmr_wdclr( lua_State *L )
+{
+  // Suspend ourselves momentarily to let the IDLE task do its thing
+  vTaskDelay(1);
+  return 0;
+}
+
+
 // Module function map
 
 LROT_BEGIN(tmr_dyn, NULL, LROT_MASK_GC_INDEX)
@@ -249,6 +258,7 @@ LROT_END(tmr_dyn, NULL, LROT_MASK_GC_INDEX)
 
 LROT_BEGIN(tmr, NULL, 0)
   LROT_FUNCENTRY( create,       tmr_create )
+  LROT_FUNCENTRY( wdclr,        tmr_wdclr )
   LROT_NUMENTRY ( ALARM_SINGLE, TIMER_MODE_SINGLE )
   LROT_NUMENTRY ( ALARM_SEMI,   TIMER_MODE_SEMI )
   LROT_NUMENTRY ( ALARM_AUTO,   TIMER_MODE_AUTO )

docs/modules/tmr.md

@@ -212,3 +212,37 @@ none
 
 #### See also
 [`tmr.obj:register()`](#tmrobjregister)
+
+
+## tmr.wdclr()
+
+Resets the watchdog timer to prevent a reboot due to a perceived hung task.
+
+Use with caution, as this could prevent a reboot to recover from a
+genuinely hung task.
+
+On the ESP32, the `tmr.wdclr()` function is implemented as a task yield
+to let the system "IDLE" task do the necessary watchdog maintenance.
+Overuse of this function is likely to result in degraded performance.
+
+#### Syntax
+`tmr.wdclr()`
+
+#### Parameters
+none
+
+#### Returns
+`nil`
+
+#### Example
+```lua
+function long_running_function()
+  while 1
+  do
+    if some_condition then break end
+    -- do some heavy calculation here, for example
+    tmr.wdclr()
+  end
+end
+```
+