fan: update timer alarm value

Author: redchenjs

main/src/user/fan.c

@@ -82,7 +82,7 @@ static void tim_init(void)
     };
     timer_init(TIMER_GROUP_0, TIMER_0, &tim_conf);
 
-    timer_set_alarm_value(TIMER_GROUP_0, TIMER_0, 500000ULL);
+    timer_set_alarm_value(TIMER_GROUP_0, TIMER_0, 750000ULL);
 
     timer_enable_intr(TIMER_GROUP_0, TIMER_0);
     timer_isr_register(TIMER_GROUP_0, TIMER_0, tim_isr_handler, NULL, ESP_INTR_FLAG_IRAM, NULL);