Add generic GPS UART and NMEA diagnostics

src/helpers/CommonCLI.cpp

@@ -344,6 +344,20 @@ void CommonCLI::handleCommand(uint32_t sender_timestamp, char* command, char* re
       } else {
         strcpy(reply, "gps provider not found");
       }
+    } else if (strcmp(command, "gps diag") == 0) {
+      LocationProvider * l = _sensors->getLocationProvider();
+      if (l != NULL) {
+        const char* setting = _sensors->getSettingByKey("gps");
+        bool requested = setting != NULL && strcmp(setting, "1") == 0;
+        int prefix_len = snprintf(reply, 160, "req:%u ", requested ? 1U : 0U);
+        if (prefix_len < 0 || prefix_len >= 160) {
+          reply[159] = 0;
+        } else {
+          l->formatDiagnostics(reply + prefix_len, 160 - prefix_len);
+        }
+      } else {
+        strcpy(reply, "gps provider not found");
+      }
     } else if (memcmp(command, "gps setloc", 10) == 0) {
       _prefs->node_lat = _sensors->node_lat;
       _prefs->node_lon = _sensors->node_lon;

src/helpers/sensors/LocationProvider.h

@@ -1,6 +1,8 @@
 #pragma once
 
 #include "Mesh.h"
+#include <stddef.h>
+#include <stdio.h>
 
 
 class LocationProvider {
@@ -22,4 +24,14 @@ class LocationProvider {
     virtual void stop() = 0;
     virtual void loop() = 0;
     virtual bool isEnabled() = 0;
+
+    // Format compact diagnostics in the caller-provided buffer. Providers that
+    // have more information (for example UART counters) can override this.
+    virtual void formatDiagnostics(char* out, size_t out_size) {
+        if (out_size == 0) return;
+        snprintf(out, out_size, "en:%u sat:%ld fix:%u",
+            isEnabled() ? 1U : 0U,
+            satellitesCount(),
+            isValid() ? 1U : 0U);
+    }
 };

src/helpers/sensors/MicroNMEALocationProvider.h

@@ -4,6 +4,7 @@
 #include <MicroNMEA.h>
 #include <RTClib.h>
 #include <helpers/RefCountedDigitalPin.h>
+#include <string.h>
 
 #ifndef GPS_EN
     #ifdef PIN_GPS_EN
@@ -51,6 +52,32 @@ class MicroNMEALocationProvider : public LocationProvider {
     unsigned long _last_time_sync = 0;
     static const unsigned long TIME_SYNC_INTERVAL = 1800000; // Re-sync every 30 minutes
 
+    // Observation-only diagnostics. These fields do not change GPS power,
+    // timing, reset behaviour, or parser input.
+    uint32_t _uart_bytes = 0;
+    uint32_t _nmea_checksum_ok = 0;
+    uint32_t _nmea_checksum_bad = 0;
+    uint32_t _begin_calls = 0;
+    uint32_t _stop_calls = 0;
+    unsigned long _last_uart_ms = 0;
+    unsigned long _last_nmea_ms = 0;
+    unsigned long _last_fix_ms = 0;
+    bool _uart_seen = false;
+    bool _nmea_seen = false;
+    bool _fix_seen = false;
+
+    static uint32_t ageMs(unsigned long timestamp) {
+        return (uint32_t)(millis() - timestamp);
+    }
+
+    static void formatAge(char* out, size_t out_size, bool seen, unsigned long timestamp) {
+        if (!seen) {
+            snprintf(out, out_size, "never");
+        } else {
+            snprintf(out, out_size, "%lu", (unsigned long)ageMs(timestamp));
+        }
+    }
+
 public :
     MicroNMEALocationProvider(Stream& ser, mesh::RTCClock* clock = NULL, int pin_reset = GPS_RESET, int pin_en = GPS_EN,RefCountedDigitalPin* peripher_power=NULL) :
     nmea(_nmeaBuffer, sizeof(_nmeaBuffer)), _clock(clock), _gps_serial(&ser), _peripher_power(peripher_power), _pin_reset(pin_reset), _pin_en(pin_en) {
@@ -76,6 +103,7 @@ public :
     }
 
     void begin() override {
+        _begin_calls++;
         claim();
         if (_pin_en != -1) {
             digitalWrite(_pin_en, GPS_EN_ACTIVE);
@@ -94,6 +122,7 @@ public :
     }
 
     void stop() override {
+        _stop_calls++;
         if (_pin_en != -1) {
             digitalWrite(_pin_en, !GPS_EN_ACTIVE);
         }
@@ -137,10 +166,36 @@ public :
 
         while (_gps_serial->available()) {
             char c = _gps_serial->read();
+            _uart_bytes++;
+            _last_uart_ms = millis();
+            _uart_seen = true;
             #ifdef GPS_NMEA_DEBUG
             Serial.print(c);
             #endif
-            nmea.process(c);
+            bool parsed = nmea.process(c);
+
+            // MicroNMEA leaves the completed sentence in its buffer after the
+            // first line terminator. CRLF therefore counts once: CR observes the
+            // sentence, then LF clears the now-empty buffer.
+            if ((c == '\0' || c == '\r' || c == '\n') && nmea.getSentence()[0] != '\0') {
+                if (MicroNMEA::testChecksum(nmea.getSentence())) {
+                    _nmea_checksum_ok++;
+                    _last_nmea_ms = millis();
+                    _nmea_seen = true;
+
+                    // Refresh fix age only when a newly parsed GGA/RMC sentence
+                    // carries a valid fix. Other valid NMEA sentences must not
+                    // make an old position look fresh.
+                    const char* message_id = nmea.getMessageID();
+                    if (parsed && isValid() &&
+                        (strcmp(message_id, "GGA") == 0 || strcmp(message_id, "RMC") == 0)) {
+                        _last_fix_ms = millis();
+                        _fix_seen = true;
+                    }
+                } else {
+                    _nmea_checksum_bad++;
+                }
+            }
         }
 
         if (!isValid()) time_valid = 0;
@@ -163,4 +218,31 @@ public :
             }
         }
     }
+
+    void formatDiagnostics(char* out, size_t out_size) override {
+        if (out_size == 0) return;
+
+        char uart_age[11];
+        char nmea_age[11];
+        char fix_age[11];
+        formatAge(uart_age, sizeof(uart_age), _uart_seen, _last_uart_ms);
+        formatAge(nmea_age, sizeof(nmea_age), _nmea_seen, _last_nmea_ms);
+        formatAge(fix_age, sizeof(fix_age), _fix_seen, _last_fix_ms);
+
+        // Compact enough for CommonCLI's 160-byte reply buffer, including the
+        // "req:" prefix added by CommonCLI.
+        snprintf(out, out_size,
+            "en:%u ub:%lu ua:%s ok:%lu bad:%lu na:%s sat:%ld fix:%u fa:%s bc:%lu sc:%lu",
+            isEnabled() ? 1U : 0U,
+            (unsigned long)_uart_bytes,
+            uart_age,
+            (unsigned long)_nmea_checksum_ok,
+            (unsigned long)_nmea_checksum_bad,
+            nmea_age,
+            satellitesCount(),
+            isValid() ? 1U : 0U,
+            fix_age,
+            (unsigned long)_begin_calls,
+            (unsigned long)_stop_calls);
+    }
 };