From 494d72503ac353a17d955d8fe72442d3df4f1595 Mon Sep 17 00:00:00 2001
From: Peter Barker <pbarker@barker.dropbear.id.au>
Date: Mon, 19 Feb 2024 10:57:18 +1100
Subject: [PATCH] AP_GPS: use probing when probing for GPS, add detected
 message

---
 libraries/AP_GPS/AP_GPS.cpp      | 8 ++++++++
 libraries/AP_GPS/AP_GPS.h        | 1 +
 libraries/AP_GPS/GPS_Backend.cpp | 2 +-
 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/libraries/AP_GPS/AP_GPS.cpp b/libraries/AP_GPS/AP_GPS.cpp
index 25a790787a..52f622458e 100644
--- a/libraries/AP_GPS/AP_GPS.cpp
+++ b/libraries/AP_GPS/AP_GPS.cpp
@@ -999,6 +999,14 @@ void AP_GPS::update_instance(uint8_t instance)
             tnow = state[instance].last_corrected_gps_time_us/1000U;
             state[instance].corrected_timestamp_updated = false;
         }
+
+        // we set delta_time_ms to the timeout value when clearing
+        // state; use it being zero to mark first message
+        if (!state[instance].announced_detection) {
+            state[instance].announced_detection = true;
+            GCS_SEND_TEXT(MAV_SEVERITY_INFO, "GPS %d: detected %s", instance + 1, drivers[instance]->name());
+        }
+
         // delta will only be correct after parsing two messages
         timing[instance].delta_time_ms = tnow - timing[instance].last_message_time_ms;
         timing[instance].last_message_time_ms = tnow;
diff --git a/libraries/AP_GPS/AP_GPS.h b/libraries/AP_GPS/AP_GPS.h
index a5ca9cdcea..b48bf453a4 100644
--- a/libraries/AP_GPS/AP_GPS.h
+++ b/libraries/AP_GPS/AP_GPS.h
@@ -212,6 +212,7 @@ public:
         float undulation;                   //<height that WGS84 is above AMSL at the current location
         bool have_undulation;               ///<do we have a value for the undulation
         uint32_t last_gps_time_ms;          ///< the system time we got the last GPS timestamp, milliseconds
+        bool announced_detection;           ///< true once we have announced GPS has been seen to the user
         uint64_t last_corrected_gps_time_us;///< the system time we got the last corrected GPS timestamp, microseconds
         bool corrected_timestamp_updated;  ///< true if the corrected timestamp has been updated
         uint32_t lagged_sample_count;       ///< number of samples with 50ms more lag than expected
diff --git a/libraries/AP_GPS/GPS_Backend.cpp b/libraries/AP_GPS/GPS_Backend.cpp
index f6d08fc761..8147be2449 100644
--- a/libraries/AP_GPS/GPS_Backend.cpp
+++ b/libraries/AP_GPS/GPS_Backend.cpp
@@ -136,7 +136,7 @@ void AP_GPS_Backend::_detection_message(char *buffer, const uint8_t buflen) cons
 
     if (dstate.auto_detected_baud) {
         hal.util->snprintf(buffer, buflen,
-                 "GPS %d: detected as %s at %d baud",
+                 "GPS %d: probing for %s at %d baud",
                  instance + 1,
                  name(),
                  int(gps._baudrates[dstate.current_baud]));