fix: correct XIAO RS485 UART pin mapping

firmware/esp32-s3-dashboard/dashboard_config.h

@@ -1,6 +1,6 @@
 #pragma once
 
-static const char *DASHBOARD_VERSION = "0.1.131-rs485-sensor-stats";
+static const char *DASHBOARD_VERSION = "0.1.132-rs485-raw-diagnostics";
 
 // First-boot defaults. Credentials are stored in Preferences/NVS after setup.
 static const char *DASHBOARD_DEFAULT_CARGO_WIFI_SSID = "OverlandController";

firmware/esp32-s3-dashboard/esp32-s3-dashboard.ino

@@ -687,6 +687,12 @@ static void update_diagnostics_overlay()
     text += String(sensor_node.framesDropped);
     text += "/";
     text += String(sensor_node.parseErrors + sensor_node.oversizedFrames);
+    text += "\n  Raw bytes/age: ";
+    text += String(sensor_node.bytesReceived);
+    text += "/";
+    text += sensor_node.bytesReceived
+        ? String(millis() - sensor_node.lastByteMs) + " ms"
+        : String("--");
     text += "\n  Frame age: ";
     text += sensor_node.frameReceived
         ? String(millis() - sensor_node.lastFrameMs) + " ms"

firmware/esp32-s3-dashboard/sensor_node_receiver.cpp

@@ -117,6 +117,8 @@ void initSensorNodeRs485() {
 void processSensorNodeRs485() {
     while (sensorNodeSerial.available() > 0) {
         char value = (char)sensorNodeSerial.read();
+        sensorNodeStatus.bytesReceived++;
+        sensorNodeStatus.lastByteMs = millis();
         if (value == '\r') continue;
 
         if (value != '\n') {

firmware/esp32-s3-dashboard/sensor_node_receiver.h

@@ -16,6 +16,7 @@ struct SensorNodeDashboardStatus {
     uint32_t framesDropped = 0;
     uint32_t parseErrors = 0;
     uint32_t oversizedFrames = 0;
+    uint32_t bytesReceived = 0;
     uint32_t nodeRestarts = 0;
     uint32_t satellites = 0;
     float pitchDegrees = 0;
@@ -29,6 +30,7 @@ struct SensorNodeDashboardStatus {
     String stability = "unknown";
     String firmwareVersion;
     String utcTime;
+    unsigned long lastByteMs = 0;
     unsigned long lastFrameMs = 0;
 };