Setting RTC to GPS with 1PPS precision working. Here is an example log:

20260217_200901_z	 set RTC to GPS using 1PPS pulse-per-second discipline	rtc-gps drift=-28 s
20260217_201001_z	 set RTC to GPS using 1PPS pulse-per-second discipline	rtc-gps drift=+0 s
20260217_201119_z	 set RTC to GPS using 1PPS pulse-per-second discipline	rtc-gps drift=+0 s
20260217_201219_z	 set RTC to GPS using 1PPS pulse-per-second discipline	rtc-gps drift=+0 s

exercises/11_Set_RTC2GPS/lib/startup_sd/StartupSdManager.h

@@ -0,0 +1,90 @@
+#pragma once
+
+#include <Arduino.h>
+#include <SD.h>
+#include <SPI.h>
+#include <Wire.h>
+#include "tbeam_supreme_adapter.h"
+
+enum class SdWatchState : uint8_t {
+  UNKNOWN = 0,
+  ABSENT,
+  MOUNTED
+};
+
+enum class SdEvent : uint8_t {
+  NO_CARD,
+  CARD_MOUNTED,
+  CARD_REMOVED
+};
+
+using SdStatusCallback = void (*)(SdEvent event, const char* message);
+
+struct SdWatcherConfig {
+  bool enableSdRailCycle = true;
+  bool enablePinDumps = true;
+  bool recoveryRailCycleOnFullScan = true;
+  uint32_t recoveryRailOffMs = 250;
+  uint32_t recoveryRailOnSettleMs = 700;
+  uint32_t startupWarmupMs = 1500;
+  uint32_t pollIntervalAbsentMs = 1000;
+  uint32_t pollIntervalMountedMs = 2000;
+  uint32_t fullScanIntervalMs = 10000;
+  uint8_t votesToPresent = 2;
+  uint8_t votesToAbsent = 5;
+};
+
+class StartupSdManager {
+ public:
+  explicit StartupSdManager(Print& serial = Serial);
+
+  bool begin(const SdWatcherConfig& cfg, SdStatusCallback callback = nullptr);
+  void update();
+
+  bool isMounted() const { return watchState_ == SdWatchState::MOUNTED; }
+  SdWatchState state() const { return watchState_; }
+
+  bool consumeMountedEvent();
+  bool consumeRemovedEvent();
+
+  void printCardInfo();
+  bool ensureDirRecursive(const char* path);
+  bool rewriteFile(const char* path, const char* payload);
+  void permissionsDemo(const char* path);
+
+ private:
+  void logf(const char* fmt, ...);
+  void notify(SdEvent event, const char* message);
+  void forceSpiDeselected();
+  void dumpSdPins(const char* tag);
+  bool initPmuForSdPower();
+  void cycleSdRail(uint32_t offMs = 250, uint32_t onSettleMs = 600);
+  bool tryMountWithBus(SPIClass& bus, const char* busName, uint32_t hz, bool verbose);
+  bool mountPreferred(bool verbose);
+  bool mountCardFullScan();
+  bool verifyMountedCard();
+  const char* cardTypeToString(uint8_t type);
+  void setStateMounted();
+  void setStateAbsent();
+
+  Print& serial_;
+  SdWatcherConfig cfg_{};
+  SdStatusCallback callback_ = nullptr;
+
+  SPIClass sdSpiH_{HSPI};
+  SPIClass sdSpiF_{FSPI};
+  SPIClass* sdSpi_ = nullptr;
+  const char* sdBusName_ = "none";
+  uint32_t sdFreq_ = 0;
+  XPowersLibInterface* pmu_ = nullptr;
+
+  SdWatchState watchState_ = SdWatchState::UNKNOWN;
+  uint8_t presentVotes_ = 0;
+  uint8_t absentVotes_ = 0;
+  uint32_t lastPollMs_ = 0;
+  uint32_t lastFullScanMs_ = 0;
+  uint32_t logSeq_ = 0;
+
+  bool mountedEventPending_ = false;
+  bool removedEventPending_ = false;
+};