Updated refresh logic to only rerender calendar, when contents changed.

esphome/epaperframe.yaml

@@ -22,6 +22,8 @@ esp32:
   board: nodemcu-32s
   framework:
     type: esp-idf
+    advanced: 
+      minimum_chip_revision: "3.0"
 
 wifi:
   ssid: "Voltage-legacy"
@@ -49,6 +51,13 @@ api:
 # Include ArduinoJson support for the compact calendar event feed.
 json:
 
+# Avoid refreshing the panel when Home Assistant republishes unchanged calendar data.
+globals:
+  - id: last_rendered_calendar_entries
+    type: std::string
+    restore_value: no
+    initial_value: '""'
+
 ota:
   platform: esphome
   password: !secret ota
@@ -220,6 +229,17 @@ text_sensor:
     entity_id: sensor.epaper_kalenderdaten
     attribute: entries
     id: calendar_entries
+    on_value:
+      then:
+        - if:
+            condition:
+              and:
+                - display.is_displaying_page: calendar
+                - lambda: return x != id(last_rendered_calendar_entries);
+            then:
+              - lambda: id(last_rendered_calendar_entries) = x;
+              - component.update: epaper
+
 
   # Home Assistant selects one quote per day from its local quote library.
   - platform: homeassistant
@@ -241,14 +261,19 @@ time:
           - output.turn_on: power_key
           - delay: 0.5s
           - output.turn_off: power_key
-      # Every 10 minutes
+      # Refresh environmental readings every 10 minutes. The calendar page is
+      # redrawn only when its event feed actually changes.
       - seconds: 0
         minutes: /10
         then:
-          - logger.log:
-              level: INFO
-              format: "Timer based screen refresh"
-          - component.update: epaper
+          - if:
+              condition:
+                display.is_displaying_page: environment
+              then:
+                - logger.log:
+                    level: INFO
+                    format: "Timer based environment screen refresh"
+                - component.update: epaper
 
 # Font definitions
 font:
@@ -1289,7 +1314,7 @@ display:
           it.strftime(614, 380, id(footer_font), TextAlign::BASELINE_RIGHT,
                       "Aktualisiert um %d.%m.%Y %H:%M", now);
 
-          /* WiFi Signal Strenght */
+          /* WiFi Signal strength */
           if(id(wifisignal).has_state()) {
             int x = 630;
             int y = 384;