Notify: Display: blank text line after 10s

libraries/AP_Notify/AP_Notify.cpp

@@ -170,6 +170,7 @@ void AP_Notify::init(bool enable_external_leds)
     // clear flight mode string and text buffer
     memset(_flight_mode_str, 0, sizeof(_flight_mode_str));
     memset(_send_text, 0, sizeof(_send_text));
+    _send_text_updated_millis = 0;
 
     AP_Notify::flags.external_leds = enable_external_leds;
 
@@ -217,4 +218,5 @@ void AP_Notify::send_text(const char *str)
 {
     strncpy(_send_text, str, sizeof(_send_text));
     _send_text[sizeof(_send_text)-1] = 0;
+    _send_text_updated_millis = AP_HAL::millis();
 }

libraries/AP_Notify/AP_Notify.h

@@ -140,6 +140,7 @@ private:
     AP_Int8 _display_type;
 
     char _send_text[NOTIFY_TEXT_BUFFER_SIZE];
+    uint32_t _send_text_updated_millis; // last time text changed
     char _flight_mode_str[5];
 
     static NotifyDevice* _devices[];

libraries/AP_Notify/Display.cpp

@@ -488,11 +488,26 @@ void Display::update_mode(uint8_t r)
 	}
 }
 
+void Display::update_text_empty(uint8_t r)
+{
+    char msg [DISPLAY_MESSAGE_SIZE] = {};
+    memset(msg, ' ', sizeof(msg)-1);
+    _movedelay = 0;
+    _mstartpos = 0;
+    draw_text(COLUMN(0), ROW(r), msg);
+}
+
 void Display::update_text(uint8_t r)
 {
     char msg [DISPLAY_MESSAGE_SIZE];
     char txt [NOTIFY_TEXT_BUFFER_SIZE];
 
+    const bool text_is_valid = AP_HAL::millis() - pNotify->_send_text_updated_millis < _send_text_valid_millis;
+    if (!text_is_valid) {
+        update_text_empty(r);
+        return;
+    }
+
     snprintf(txt, NOTIFY_TEXT_BUFFER_SIZE, "%s", pNotify->get_text());
     _mstartpos++;
     for (uint8_t i = 0; i < sizeof(msg); i++) {

libraries/AP_Notify/Display.h

@@ -28,6 +28,7 @@ private:
     void update_battery(uint8_t r);
     void update_mode(uint8_t r);
     void update_text(uint8_t r);
+    void update_text_empty(uint8_t r);
 
     Display_Backend *_driver;
 
@@ -36,5 +37,8 @@ private:
     uint8_t _mstartpos;
     uint8_t _movedelay;
     uint8_t _screenpage;
+
+    // stop showing text in display after this many millis:
+    const uint16_t _send_text_valid_millis = 20000;
 };