Release v2.0.0 with dual-nail control and hardened safety

piNail2/thermocouple.py

@@ -10,6 +10,9 @@ Wraps the MAX6675 thermocouple reader with:
 
 import logging
 import collections
+import math
+import importlib
+import types
 
 log = logging.getLogger(__name__)
 
@@ -48,8 +51,29 @@ class Thermocouple:
         self._total_reads = 0
 
         try:
-            import MAX6675.MAX6675 as MAX6675
-            self._sensor = MAX6675.MAX6675(clk, cs, do)
+            sensor_ctor = None
+            module_candidates = [
+                ("MAX6675.MAX6675", "MAX6675"),
+                ("MAX6675.MAX6675.MAX6675", "MAX6675"),
+                ("MAX6675.MAX6675", None),
+                ("MAX6675.MAX6675.MAX6675", None),
+            ]
+            for module_name, attr_name in module_candidates:
+                try:
+                    module = importlib.import_module(module_name)
+                except Exception:
+                    continue
+
+                obj = getattr(module, attr_name, None) if attr_name else module
+                if isinstance(obj, types.ModuleType):
+                    obj = getattr(obj, "MAX6675", None)
+                if callable(obj):
+                    sensor_ctor = obj
+                    break
+
+            if not callable(sensor_ctor):
+                raise TypeError("MAX6675 constructor unavailable")
+            self._sensor = sensor_ctor(clk, cs, do)
             self._is_connected = True
             log.info("MAX6675 thermocouple initialized (CLK=%d, CS=%d, DO=%d)", clk, cs, do)
         except Exception as e:
@@ -76,8 +100,20 @@ class Thermocouple:
             self._is_connected = False
             return self._last_good_temp
 
-        # Check for open thermocouple (MAX6675 returns very high values or specific error codes)
-        if raw_c is None or raw_c > 1023:
+        # Check for open thermocouple / invalid frame.
+        # MAX6675 open probe often reports NaN; guard all non-finite values.
+        if raw_c is None:
+            log.warning("Thermocouple appears disconnected (raw_c=%s)", raw_c)
+            self._is_connected = False
+            return self._last_good_temp
+        try:
+            raw_c = float(raw_c)
+        except (TypeError, ValueError):
+            log.warning("Thermocouple appears disconnected (raw_c=%s)", raw_c)
+            self._is_connected = False
+            return self._last_good_temp
+
+        if (not math.isfinite(raw_c)) or raw_c > 1023:
             log.warning("Thermocouple appears disconnected (raw_c=%s)", raw_c)
             self._is_connected = False
             return self._last_good_temp
@@ -149,10 +185,15 @@ class Thermocouple:
     @property
     def stats(self):
         """Return diagnostic stats."""
+        def safe(value):
+            if isinstance(value, (int, float)) and math.isfinite(float(value)):
+                return round(float(value), 2)
+            return None
+
         return {
-            "raw_temp": round(self._raw_temp, 2),
-            "filtered_temp": round(self._filtered_temp, 2),
+            "raw_temp": safe(self._raw_temp),
+            "filtered_temp": safe(self._filtered_temp),
             "is_connected": self._is_connected,
             "total_reads": self._total_reads,
-            "recent_readings": [round(r, 2) for r in self._readings],
+            "recent_readings": [safe(r) for r in self._readings],
         }