diff --git a/exercises/05_SD_Card_Watcher/src/main.cpp b/exercises/05_SD_Card_Watcher/src/main.cpp
index 6a1cd6f..f3f4373 100644
--- a/exercises/05_SD_Card_Watcher/src/main.cpp
+++ b/exercises/05_SD_Card_Watcher/src/main.cpp
@@ -7,13 +7,14 @@
 #include <FS.h>
 #include <SD.h>
 #include <SPI.h>
+#include "driver/gpio.h"          // gpio_get_level()
 #include "tbeam_supreme_adapter.h"
 
 // -------------------------
 // Configuration toggles
 // -------------------------
 #define ENABLE_SD_RAIL_CYCLE    1   // Power-cycle AXP2101 BLDO1 (SD rail) at boot.
-#define ENABLE_PIN_DUMPS        1   // Log SPI pin logic levels at key points.
+#define ENABLE_PIN_DUMPS        1   // Log SPI pin logic levels at key points (NON-INTRUSIVE).
 #define STARTUP_SERIAL_DELAY_MS 5000
 
 // -------------------------
@@ -77,8 +78,6 @@ static void dumpPmu(const char* tag, XPowersLibInterface* pmu) {
   }
 
   bool bldo1 = pmu->isPowerChannelEnable(XPOWERS_BLDO1);
-
-  // Adapter enables these measures in initPmuForPeripherals().
   int vbus = pmu->getVbusVoltage();
   int batt = pmu->getBattVoltage();
 
@@ -86,27 +85,20 @@ static void dumpPmu(const char* tag, XPowersLibInterface* pmu) {
        tag, bldo1 ? "ON" : "OFF", vbus, batt);
 }
 
+// IMPORTANT: this function MUST NOT modify pin modes (regression cause).
 static void dumpSdPins(const char* tag) {
 #if ENABLE_PIN_DUMPS
-  const int CS   = tbeam_supreme::sdCs();
-  const int SCK  = tbeam_supreme::sdSck();
-  const int MISO = tbeam_supreme::sdMiso();
-  const int MOSI = tbeam_supreme::sdMosi();
+  const gpio_num_t CS   = (gpio_num_t)tbeam_supreme::sdCs();
+  const gpio_num_t SCK  = (gpio_num_t)tbeam_supreme::sdSck();
+  const gpio_num_t MISO = (gpio_num_t)tbeam_supreme::sdMiso();
+  const gpio_num_t MOSI = (gpio_num_t)tbeam_supreme::sdMosi();
 
-  // Use pullups to make floating lines visible.
-  pinMode(CS,   INPUT_PULLUP);
-  pinMode(SCK,  INPUT_PULLUP);
-  pinMode(MISO, INPUT_PULLUP);
-  pinMode(MOSI, INPUT_PULLUP);
+  int cs   = gpio_get_level(CS);
+  int sck  = gpio_get_level(SCK);
+  int miso = gpio_get_level(MISO);
+  int mosi = gpio_get_level(MOSI);
 
-  delay(2);
-
-  logf("PINS(%s): CS=%d SCK=%d MISO=%d MOSI=%d",
-       tag,
-       digitalRead(CS),
-       digitalRead(SCK),
-       digitalRead(MISO),
-       digitalRead(MOSI));
+  logf("PINS(%s): CS=%d SCK=%d MISO=%d MOSI=%d", tag, cs, sck, miso, mosi);
 #else
   (void)tag;
 #endif
@@ -116,7 +108,6 @@ static void dumpSdPins(const char* tag) {
 // Power + bus conditioning
 // -------------------------
 static void forceSpiDeselected() {
-  // Keep SD and IMU deselected (shared bus risk if IMU CS floats low).
   pinMode(tbeam_supreme::sdCs(), OUTPUT);
   digitalWrite(tbeam_supreme::sdCs(), HIGH);
 
@@ -126,13 +117,14 @@ static void forceSpiDeselected() {
 
 static bool initPmuForSdPower() {
   bool ok = tbeam_supreme::initPmuForPeripherals(g_pmu, &Serial);
-  if (ok) {
-    logf("PMU adapter: AXP2101 ready, BLDO1(SD)=%s",
-         g_pmu && g_pmu->isPowerChannelEnable(XPOWERS_BLDO1) ? "ON" : "OFF");
-  } else {
+  if (!ok) {
     logf("ERROR: PMU init failed");
+    return false;
   }
-  return ok;
+
+  logf("PMU adapter: AXP2101 ready, BLDO1(SD)=%s",
+       g_pmu && g_pmu->isPowerChannelEnable(XPOWERS_BLDO1) ? "ON" : "OFF");
+  return true;
 }
 
 static void cycleSdRail(XPowersLibInterface* pmu,
@@ -153,7 +145,6 @@ static void cycleSdRail(XPowersLibInterface* pmu,
   pmu->disablePowerOutput(XPOWERS_BLDO1);
   delay(off_ms);
 
-  // Re-assert voltage and enable.
   pmu->setPowerChannelVoltage(XPOWERS_BLDO1, 3300);
   pmu->enablePowerOutput(XPOWERS_BLDO1);
   delay(on_settle_ms);
@@ -201,9 +192,7 @@ static bool tryMountWithBus(SPIClass& bus, const char* busName, uint32_t hz, boo
   }
 
   if (!SD.begin(tbeam_supreme::sdCs(), bus, hz)) {
-    if (verbose) {
-      logf("SD: mount failed (possible non-FAT format, power, or bus issue)");
-    }
+    if (verbose) logf("SD: mount failed (possible non-FAT format, power, or bus issue)");
     return false;
   }
 
@@ -220,7 +209,6 @@ static bool tryMountWithBus(SPIClass& bus, const char* busName, uint32_t hz, boo
 }
 
 static bool mountPreferred(bool verbose) {
-  // Conservative: HSPI @ 400kHz is the most forgiving initial probe.
   return tryMountWithBus(sdSpiH, "HSPI", 400000, verbose);
 }
 
@@ -406,7 +394,7 @@ void setup() {
   initPmuForSdPower();
   dumpPmu("post-pmu-init", g_pmu);
 
-  // Software equivalent of "remove/insert card" that fixes your issue.
+  // Software equivalent of "remove/insert card".
   cycleSdRail(g_pmu);
 
   logf("Watcher: waiting %lu ms for SD rail/card stabilization", (unsigned long)kStartupWarmupMs);
@@ -414,7 +402,6 @@ void setup() {
 
   dumpSdPins("pre-warmup-mount");
 
-  // Warm-up attempts before first status decision.
   bool warmMounted = false;
   for (uint8_t i = 0; i < 3; ++i) {
     if (mountPreferred(false)) {