Update the default P and I terms by TCXO type

Author: PaulZC

Firmware/GNSSDO_Firmware/Begin.ino

@@ -524,6 +524,15 @@ void beginTCXO(TwoWire *i2cBus)
 
         if (!myTCXO->begin(*i2cBus, SFE_GNSSDO_OSC_STP3593LF))
             return;
+
+        if (settings.lastSeenTCXO != SFE_GNSSDO_OSC_STP3593LF)
+        {
+            // Update the default P and I terms to match a new oscillator
+            settings.lastSeenTCXO = SFE_GNSSDO_OSC_STP3593LF;
+            settings.Pk = myTCXO->getDefaultFrequencyByBiasPTerm();
+            settings.Ik = myTCXO->getDefaultFrequencyByBiasITerm();
+            recordSystemSettings();
+        }
 
         systemPrintln("Using STP3593LF OCXO");
     }
@@ -534,6 +543,15 @@ void beginTCXO(TwoWire *i2cBus)
         if (!myTCXO->begin(*i2cBus, SFE_GNSSDO_OSC_SIT5811))
             return;
 
+        if (settings.lastSeenTCXO != SFE_GNSSDO_OSC_SIT5811)
+        {
+            // Update the default P and I terms to match a new oscillator
+            settings.lastSeenTCXO = SFE_GNSSDO_OSC_SIT5811;
+            settings.Pk = myTCXO->getDefaultFrequencyByBiasPTerm();
+            settings.Ik = myTCXO->getDefaultFrequencyByBiasITerm();
+            recordSystemSettings();
+        }
+        
         systemPrintln("Using SiT5811 OCXO");
     }
     else if (presentSIT5358)
@@ -543,6 +561,15 @@ void beginTCXO(TwoWire *i2cBus)
         if (!myTCXO->begin(*i2cBus, SFE_GNSSDO_OSC_SIT5358))
             return;
 
+        if (settings.lastSeenTCXO != SFE_GNSSDO_OSC_SIT5358)
+        {
+            // Update the default P and I terms to match a new oscillator
+            settings.lastSeenTCXO = SFE_GNSSDO_OSC_SIT5358;
+            settings.Pk = myTCXO->getDefaultFrequencyByBiasPTerm();
+            settings.Ik = myTCXO->getDefaultFrequencyByBiasITerm();
+            recordSystemSettings();
+        }
+        
         systemPrintln("Using SiT5358 TCXO");
     }
     else

Firmware/GNSSDO_Firmware/GNSSDO_TCXO.h

@@ -24,6 +24,10 @@ class GNSSDO_TCXO
 
         // Save the frequency control word - if supported
         virtual bool saveFrequencyControlValue(void);
+
+        // Get the default P and I terms - for the default settings
+        virtual double getDefaultFrequencyByBiasPTerm(void);
+        virtual double getDefaultFrequencyByBiasITerm(void);
 };
 
 #endif // /__SFE_GNSSDO_TCXO__

Firmware/GNSSDO_Firmware/NVM.ino

@@ -96,6 +96,7 @@ void recordSystemSettingsToFile(File *settingsFile)
     settingsFile->printf("%s=%d\r\n", "rxClkBiasLimitCount", settings.rxClkBiasLimitCount);
     settingsFile->printf("%s=%0.3e\r\n", "Pk", settings.Pk);
     settingsFile->printf("%s=%0.3e\r\n", "Ik", settings.Ik);
+    settingsFile->printf("%s=%d\r\n", "lastSeenTCXO", settings.lastSeenTCXO);
     settingsFile->printf("%s=%d\r\n", "preferNonCompositeGPSBias", settings.preferNonCompositeGPSBias);
     settingsFile->printf("%s=%d\r\n", "preferNonCompositeGalileoBias", settings.preferNonCompositeGalileoBias);
     settingsFile->printf("%s=%d\r\n", "enableTCPServer", settings.enableTCPServer);
@@ -365,6 +366,8 @@ bool parseLine(char *str, Settings *settings)
         settings->Pk = d;
     else if (strcmp(settingName, "Ik") == 0)
         settings->Ik = d;
+    else if (strcmp(settingName, "lastSeenTCXO") == 0)
+        settings->lastSeenTCXO = d;
     else if (strcmp(settingName, "preferNonCompositeGPSBias") == 0)
         settings->preferNonCompositeGPSBias = d;
     else if (strcmp(settingName, "preferNonCompositeGalileoBias") == 0)

Firmware/GNSSDO_Firmware/STP3593LF_OCXO.h

@@ -24,6 +24,10 @@ class GNSSDO_STP3593LF : GNSSDO_TCXO
 
         // Save the frequency control word - if supported
         bool saveFrequencyControlValue(void);
+
+        // Get the default P and I terms - for the default settings
+        double getDefaultFrequencyByBiasPTerm(void) { return (1.0 / 6.25); }
+        double getDefaultFrequencyByBiasITerm(void) { return ((1.0 / 6.25) / 150.0); }
 };
 
 #endif // /__SFE_GNSSDO_STP3593LF_TCXO__

Firmware/GNSSDO_Firmware/STP3593LF_OCXO.ino

@@ -10,7 +10,7 @@ bool GNSSDO_STP3593LF::begin(TwoWire &wirePort, const uint8_t &address)
 
     // Don't restore the frequency control word with the saved value from settings.
     // Assume saveFrequencyControlValue has done its job and that the control word
-    // has already been restored.
+    // has already been restored by the OCXO.
 
     return true;
 }

Firmware/GNSSDO_Firmware/SiT5358_TCXO.h

@@ -24,6 +24,10 @@ class GNSSDO_SIT5358 : GNSSDO_TCXO
 
         // Save the frequency control word - if supported
         bool saveFrequencyControlValue(void);
+
+        // Get the default P and I terms - for the default settings
+        double getDefaultFrequencyByBiasPTerm(void) { return 0.63; }
+        double getDefaultFrequencyByBiasITerm(void) { return 0.151; }
 };
 
 #endif // /__SFE_GNSSDO_SIT5358_TCXO__

Firmware/GNSSDO_Firmware/SiT5811_OCXO.h

@@ -24,6 +24,10 @@ class GNSSDO_SIT5811 : GNSSDO_TCXO
 
         // Save the frequency control word - if supported
         bool saveFrequencyControlValue(void);
+
+        // Get the default P and I terms - for the default settings - TODO
+        double getDefaultFrequencyByBiasPTerm(void) { return 0.5; }
+        double getDefaultFrequencyByBiasITerm(void) { return 0.1; }
 };
 
 #endif // /__SFE_GNSSDO_SIT5811_TCXO__

Firmware/GNSSDO_Firmware/settings.h

@@ -284,10 +284,9 @@ typedef struct
     double rxClkBiasInitialLimit_ms = 1.0e-3; // Consider the clock bias 'bad' when > this many ms. Default: 1.0us (1.0e-3ms)
     double rxClkBiasLockLimit_ms = 10.0e-6; // Consider the clock locked when the bias is <= this many ms. Default: 10.0ns (10.0e-6ms)
     int rxClkBiasLimitCount = 3; // Consider the clock locked when the bias is <= rxClkBiasLockLimit_ms for this many successive readings. Default: 3
-    // The default values for Pk and Ik come from very approximate Ziegler-Nichols tuning of the SiT5358:
-    //   oscillation starts when Pk is ~1.4; with a period of ~5 seconds.
-    double Pk = 0.63; // PI P term
-    double Ik = 0.151; // PI I term
+    double Pk = 0.63; // PI P term (default for the SiT5358 - updated if needed by beginTCXO)
+    double Ik = 0.151; // PI I term (default for the SiT5358 - updated if needed by beginTCXO)
+    uint8_t lastSeenTCXO = 0; // Use this to identify a change of oscillator (by its I2C address)
     bool preferNonCompositeGPSBias = false; // Prefer non-composite GPS bias - if available. Mutex with preferNonCompositeGalileoBias
     bool preferNonCompositeGalileoBias = false; // Prefer non-composite Galileo bias - if available. Mutex with preferNonCompositeGPSBias
     bool enableTCPServer = false; // Enable and configure mosaic-T IPS1 for TCP2way for the ESP32 console