From fa212c80e603481375375de8641f071f8afc5d0b Mon Sep 17 00:00:00 2001
From: John Poole <jlpoole56@gmail.com>
Date: Fri, 17 Apr 2026 12:30:56 -0700
Subject: [PATCH] Wire vs. Wire1, still needs to be sorted out.  ChatGPT has
 some tests to clarify which I will try after this commit.  Magnetometer is on
 Wire and RTC is on Wire1, this apparently conflicts with the documentation. 
 Getting values, though when I rotated both standing up and sideways, I did
 not see values ranging from 0-360.

---
 exercises/22_compass/README.md    |  2 +-
 exercises/22_compass/src/main.cpp | 23 +++++++++++++++--------
 2 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/exercises/22_compass/README.md b/exercises/22_compass/README.md
index 4ab1bdb..634f9e0 100644
--- a/exercises/22_compass/README.md
+++ b/exercises/22_compass/README.md
@@ -205,7 +205,7 @@ Suggested workflow:
 
 ## Bottom Line
 
-The examples are enough to establish that this sensor is suitable for a live heading and magnetic field display exercise. The only caution is that the example labeled "calibration" is session-local unless we explicitly persist the offsets. The first useful deliverable for this exercise should therefore be a per-unit magnetometer assay plus a serial real-time monitor, followed by persistent calibration storage and then an OLED compass view.
+The examples are enough to establish that this sensor is suitable for a live heading and magnetic field display exercise. The only caution is that the example labeled "calibration" is session-local unless we explicitly save in non-volatile memory the offsets. The first useful deliverable for this exercise should therefore be a per-unit magnetometer assay plus a serial real-time monitor, followed by persistent calibration storage and then an OLED compass view.
 
 ## Local Helper Scripts
 
diff --git a/exercises/22_compass/src/main.cpp b/exercises/22_compass/src/main.cpp
index e694f0b..952c849 100644
--- a/exercises/22_compass/src/main.cpp
+++ b/exercises/22_compass/src/main.cpp
@@ -398,7 +398,7 @@ void startWebServer() {
     Serial.println("wifi_ap=failed");
     return;
   }
-
+  Serial.println("wifi_ap=started");
   g_server.on("/", HTTP_GET, handleWebIndex);
   g_server.on("/files", HTTP_GET, handleWebFiles);
   g_server.on("/download", HTTP_GET, handleWebDownload);
@@ -415,17 +415,24 @@ bool probeI2cAddr(TwoWire& wire, uint8_t addr) {
 }
 
 bool detectMagnetometer() {
+  Serial.printf("Detecting magnetometer, kMagCandidateCount: %u\n", kMagCandidateCount);
   for (uint8_t i = 0; i < kMagCandidateCount; ++i) {
     const uint8_t addr = kMagCandidates[i];
-    if (!probeI2cAddr(Wire1, addr)) {
+    Serial.printf("  candidate[%u] = 0x%02X\n", i, kMagCandidates[i]);
+    //
+    if (!probeI2cAddr(Wire, addr)) {
       continue;
     }
+    Serial.printf("Found device at 0x%02X, probing for magnetometer...\n", addr);
 
     if (addr == 0x3C || addr == 0x3D) {
-      Wire1.beginTransmission(addr);
-      Wire1.write((uint8_t)0x00);
-      if (Wire1.endTransmission(false) == 0 && Wire1.requestFrom((int)addr, 1) == 1) {
-        const uint8_t marker = Wire1.read();
+      //Wire1.beginTransmission(addr);
+      //Wire1.write((uint8_t)0x00);
+      //if (Wire1.endTransmission(false) == 0 && Wire1.requestFrom((int)addr, 1) == 1) {
+      Wire.beginTransmission(addr);
+      Wire.write((uint8_t)0x00);
+      if (Wire.endTransmission(false) == 0 && Wire.requestFrom((int)addr, 1) == 1) {
+        const uint8_t marker = Wire.read(); // was Wire1.read() in original code, but that seems wrong since Wire1 is a different bus
         if (marker != 0x80) {
           continue;
         }
@@ -452,7 +459,7 @@ bool initMagnetometer() {
     return false;
   }
 
-  if (!g_qmc.begin(Wire1, g_magAddress, tbeam_supreme::i2cSda(), tbeam_supreme::i2cScl())) {
+  if (!g_qmc.begin(Wire, g_magAddress, tbeam_supreme::i2cSda(), tbeam_supreme::i2cScl())) {
     return false;
   }
 
@@ -683,7 +690,7 @@ void appSetup() {
     Serial.println("sd_mount=ok");
     g_sd.printCardInfo();
   }
-
+  // Next is the failure point
   g_magReady = initMagnetometer();
   if (!g_magReady) {
     Serial.println("magnetometer_init=failed");