thinknode_m5: manage baclight

examples/companion_radio/ui-new/UITask.cpp

@@ -716,10 +716,14 @@ void UITask::loop() {
     _analogue_pin_read_millis = millis();
   }
 #endif
-#if defined(DISP_BACKLIGHT) && defined(BACKLIGHT_BTN)
+#if defined(BACKLIGHT_BTN)
   if (millis() > next_backlight_btn_check) {
     bool touch_state = digitalRead(PIN_BUTTON2);
+#if defined(DISP_BACKLIGHT)
     digitalWrite(DISP_BACKLIGHT, !touch_state);
+#elif defined(EXP_PIN_BACKLIGHT)
+    expander.digitalWrite(EXP_PIN_BACKLIGHT, !touch_state);
+#endif
     next_backlight_btn_check = millis() + 300;
   }
 #endif