freitag

README.md

@@ -99,7 +99,7 @@ Verify access: `test -w /dev/ttyUSB0 && echo ok`
    autotune 50
    ```
 
-   Emergency cutoff is fixed at **70°C** — you can autotune at 50–55°C with ABS in the chamber while hot corners stay below that.
+   Cutoff follows target (`target + 12°C`, max 95°C) — e.g. ABS at 55°C trips at 67°C corner, nylon at 80°C at 92°C.
 
 5. Dry at your target — fan runs at stir PWM (default **178**) whenever target > 0, including heat-up. Override with `fan <pwm>`; `fan auto` returns to default. Fan auto-off below 40°C applies only in idle (`target 0`).
 

include/config.h

@@ -12,6 +12,10 @@ static const uint8_t SENSOR_COUNT = sizeof(SENSOR_CHANNELS) / sizeof(SENSOR_CHAN
 // SHT31 I2C address (ADDR pin low → 0x44, high → 0x45)
 static const uint8_t SHT31_ADDRESS = 0x44;
 
+// Bus timeout (Wire.setWireTimeout) — bounds a stuck I2C transaction so a
+// glitch resets the TWI hardware instead of hanging the whole sketch.
+static const uint32_t I2C_TIMEOUT_US = 25000UL;
+
 // ---------------------------------------------------------------------------
 // Outputs — D5 has hardware PWM; heater on A2 uses burst control (SSR-friendly)
 // ---------------------------------------------------------------------------
@@ -25,9 +29,22 @@ static const float TARGET_TEMP_C = 0.0f;
 static const float AUTOTUNE_DEFAULT_TEMP_C = 40.0f;
 static const float TARGET_MIN_C = 0.0f;
 static const float TARGET_MAX_C = 80.0f;
-// Absolute max corner — heater off + full fan (decoupled from PID target).
-static const float EMERGENCY_MAX_TEMP_C = 70.0f;
-static const float CORNER_STOP_MARGIN_C = 3.0f;
+// Hard ceiling (sensor / enclosure limit). Cutoff when regulating = target + CUTOFF_ABOVE_TARGET_C.
+static const float EMERGENCY_ABSOLUTE_MAX_C = 95.0f;
+static const float CUTOFF_ABOVE_TARGET_C = 12.0f;
+static const float CUTOFF_RECOVERY_BAND_C = 5.0f;
+static const float CORNER_STOP_MARGIN_C = 5.0f;
+
+inline float emergencyCutoffForTarget(float targetC) {
+  if (targetC <= 0.0f) {
+    return EMERGENCY_ABSOLUTE_MAX_C;
+  }
+  float cutoff = targetC + CUTOFF_ABOVE_TARGET_C;
+  if (cutoff > EMERGENCY_ABSOLUTE_MAX_C) {
+    cutoff = EMERGENCY_ABSOLUTE_MAX_C;
+  }
+  return cutoff;
+}
 
 // Heat PI on average temp (no D term)
 static const float HEAT_PI_KP = 4.0f;
@@ -42,15 +59,8 @@ static const float PID_KI = HEAT_PI_KI;
 static const float PID_KD = 0.0f;
 static const float GOOD_SPREAD_C = 5.0f;
 
-// Tiered heater cap during heat-up (100% until near target)
-static const float HEATER_MAX_DUTY_COLD = 100.0f;
-static const float HEATER_MAX_DUTY_MID = 75.0f;
-static const float HEATER_MAX_DUTY_NEAR = 45.0f;
-static const float HEATER_COLD_BELOW_C = 10.0f;
-static const float HEATER_WARM_BELOW_C = 3.0f;
-// Corner taper only within this band below target (was 10°C — blocked heat-up in uneven chambers)
+// Corner taper when avg is near target — keeps hottest sensor below emergency
 static const float CORNER_LIMIT_BAND_C = 2.0f;
-static const float HEATER_SLEW_UP_PER_S = 18.0f;
 static const float MAX_TEMP_HEADROOM_C = 15.0f;
 
 static const uint16_t HEATER_CYCLE_MS = 3000;

include/pid_autotuner.h

@@ -106,7 +106,7 @@ public:
       return phase_;
     }
 
-    if (maxTempC >= EMERGENCY_MAX_TEMP_C) {
+    if (maxTempC >= emergencyCutoffForTarget(setpointC_)) {
       fail(F("autotune: abort — max sensor at emergency limit"));
       return phase_;
     }

include/thermal_controller.h

@@ -299,11 +299,13 @@ public:
 
   bool isIdle() const { return targetTempC_ <= 0.0f; }
 
+  float emergencyCutoffC() const { return emergencyCutoffForTarget(targetTempC_); }
+
   float cutoffThreshold() const {
     if (isIdle()) {
       return INFINITY;
     }
-    return EMERGENCY_MAX_TEMP_C;
+    return emergencyCutoffC();
   }
 
   bool isCutoffActive() const { return cutoffActive_; }
@@ -470,7 +472,8 @@ private:
   }
 
   void updateRegulating(float avgTempC, float maxTempC, uint32_t nowMs) {
-    if (maxTempC >= EMERGENCY_MAX_TEMP_C) {
+    const float cutoffC = emergencyCutoffC();
+    if (maxTempC >= cutoffC) {
       cutoffActive_ = true;
       heaterDutyPercent_ = 0.0f;
       heaterAllowancePercent_ = 0.0f;
@@ -480,7 +483,7 @@ private:
       return;
     }
 
-    if (cutoffActive_ && maxTempC < EMERGENCY_MAX_TEMP_C - 5.0f) {
+    if (cutoffActive_ && maxTempC < cutoffC - CUTOFF_RECOVERY_BAND_C) {
       cutoffActive_ = false;
       heatPi_.reset();
     }
@@ -494,24 +497,14 @@ private:
     heaterAllowancePercent_ = allowanceFromMaxCorner(maxTempC, avgTempC);
 
     float duty = heatPi_.compute(avgTempC, nowMs);
-    const float below = targetTempC_ - avgTempC;
-    if (below > 8.0f) {
-      const float floor = below > 15.0f ? 75.0f : 60.0f;
-      if (duty < floor) {
-        duty = floor;
-      }
-    }
-    const float maxDuty = heaterMaxDuty(avgTempC);
-    if (duty > maxDuty) {
-      duty = maxDuty;
-    }
+    duty = clampPercent(duty);
     if (duty > heaterAllowancePercent_) {
       duty = heaterAllowancePercent_;
       if (heaterAllowancePercent_ < 100.0f) {
         heaterBlock_ = HeaterBlock::Corner;
       }
     }
-    heaterDutyPercent_ = applyHeaterRamp(duty, avgTempC, nowMs);
+    heaterDutyPercent_ = duty;
 
     regulatingFanPwm_ = fanManualActive_ ? fanManualPwm_ : stirFanPwm_;
   }
@@ -532,16 +525,17 @@ private:
 
   float maxHeatStopTemp(float avgTempC) const {
     if (!shouldLimitMaxCorner(avgTempC)) {
-      return EMERGENCY_MAX_TEMP_C;
+      return emergencyCutoffC();
     }
-    return EMERGENCY_MAX_TEMP_C - CORNER_STOP_MARGIN_C;
+    return emergencyCutoffC() - CORNER_STOP_MARGIN_C;
   }
 
   float allowanceFromMaxCorner(float maxTempC, float avgTempC) const {
+    const float cutoffC = emergencyCutoffC();
     if (!shouldLimitMaxCorner(avgTempC)) {
-      // Heat-up: only taper when a hot corner nears the emergency ceiling
-      if (maxTempC >= EMERGENCY_MAX_TEMP_C - 3.0f) {
-        const float headroom = EMERGENCY_MAX_TEMP_C - maxTempC;
+      // Heat-up: only taper when a hot corner nears the dynamic cutoff
+      if (maxTempC >= cutoffC - 3.0f) {
+        const float headroom = cutoffC - maxTempC;
         return clampPercent((headroom / 3.0f) * 100.0f);
       }
       return 100.0f;
@@ -560,38 +554,6 @@ private:
     return clampPercent((headroom / MAX_TEMP_HEADROOM_C) * 100.0f);
   }
 
-  float heaterMaxDuty(float avgTempC) const {
-    if (avgTempC >= targetTempC_) {
-      return HEATER_MAX_DUTY_NEAR;
-    }
-
-    const float below = targetTempC_ - avgTempC;
-    if (below >= HEATER_COLD_BELOW_C) {
-      return HEATER_MAX_DUTY_COLD;
-    }
-    if (below >= HEATER_WARM_BELOW_C) {
-      return HEATER_MAX_DUTY_MID;
-    }
-    return HEATER_MAX_DUTY_NEAR;
-  }
-
-  float applyHeaterRamp(float requestedDuty, float avgTempC, uint32_t nowMs) {
-    const float maxDuty = heaterMaxDuty(avgTempC);
-    if (requestedDuty > maxDuty) {
-      requestedDuty = maxDuty;
-    }
-
-    if (lastHeaterUpdateMs_ > 0 && requestedDuty > heaterDutyPercent_) {
-      const float dt = static_cast<float>(nowMs - lastHeaterUpdateMs_) / 1000.0f;
-      const float maxUp = heaterDutyPercent_ + HEATER_SLEW_UP_PER_S * dt;
-      if (requestedDuty > maxUp) {
-        requestedDuty = maxUp;
-      }
-    }
-
-    return requestedDuty;
-  }
-
   void applyHeaterBurst(uint32_t nowMs) {
     if (heaterDutyPercent_ <= 0.0f) {
       forceHeaterOff();

live/dryer_20260806_190101.csv

@@ -0,0 +1,7 @@
+wall_time,ms,target_c,avg_c,min_c,max_c,spread_c,heatlim_pct,heater_pct,fan_pct,cutoff,failsafe,ch2_t,ch2_h,ch3_t,ch3_h,ch4_t,ch4_h,ch5_t,ch5_h
+2026-08-06T17:01:04+00:00,1786035664603,75.0,35.97,31.92,41.43,8.59,100,100.0,69,0,0,41.4,18,38.4,21,32.1,28,31.9,28
+2026-08-06T17:01:06+00:00,1786035666605,75.0,37.64,32.08,41.97,9.72,100,100.0,69,0,0,42.0,18,38.9,21,,,32.1,28
+2026-08-06T17:01:08+00:00,1786035668605,75.0,36.70,32.37,42.46,10.05,100,100.0,69,0,0,42.5,18,39.3,21,32.7,27,32.4,27
+2026-08-06T17:01:10+00:00,1786035670605,75.0,37.02,32.50,43.01,10.29,100,100.0,69,0,0,43.0,17,39.7,20,32.8,27,32.5,27
+2026-08-06T17:01:12+00:00,1786035672605,75.0,41.96,40.24,43.68,6.58,100,100.0,69,0,0,43.7,17,40.2,20,,,,
+2026-08-06T17:01:14+00:00,1786035674607,75.0,37.74,32.97,44.18,10.56,100,100.0,69,0,0,44.2,17,40.6,20,33.2,27,33.0,27

scripts/capture_csv.py

@@ -22,6 +22,10 @@ FALLBACK_HEADER = (
 
 SENSOR_CHANNELS = [2, 3, 4, 5]
 
+# If no bytes at all arrive for this long, treat the device as hung (e.g. an
+# I2C bus lockup freezing the Arduino) rather than looping forever in silence.
+DEFAULT_STALL_TIMEOUT_S = 20.0
+
 _FAN_PCT_RE = re.compile(r"\((\d+)%\)")
 _FAN_PWM_RE = re.compile(r"^(\d+)/")
 
@@ -206,6 +210,11 @@ def enable_dryer_logging(ser, retries: int = 3) -> None:
     print("WARN: did not see 'OK csv logging on' — continuing anyway", file=sys.stderr)
 
 
+def log_notice(message: str) -> None:
+    stamp = datetime.now(timezone.utc).isoformat(timespec="seconds")
+    print(f"{stamp} {message}", file=sys.stderr)
+
+
 def cmd_log(args: argparse.Namespace) -> int:
     from dryer_tui import parse_status
 
@@ -214,6 +223,7 @@ def cmd_log(args: argparse.Namespace) -> int:
     if out is None:
         out = args.log_dir / f"dryer_{datetime.now():%Y%m%d_%H%M%S}.csv"
 
+    stall_timeout = args.stall_timeout
     print(f"Logging {port} -> {out}", file=sys.stderr)
     if args.auto_log_on:
         print("Will send 'log on' after connect", file=sys.stderr)
@@ -223,6 +233,7 @@ def cmd_log(args: argparse.Namespace) -> int:
         if args.auto_log_on:
             enable_dryer_logging(ser)
 
+        last_activity = time.monotonic()
         while True:
             try:
                 raw = ser.readline()
@@ -230,10 +241,26 @@ def cmd_log(args: argparse.Namespace) -> int:
                 print(f"\nStopped ({session.row_count} rows).", file=sys.stderr)
                 session.close()
                 return 0
+            except Exception as exc:
+                log_notice(
+                    f"ERROR: serial read failed ({exc}) — closing after "
+                    f"{session.row_count} rows"
+                )
+                session.close()
+                return 1
 
             if not raw:
+                if time.monotonic() - last_activity >= stall_timeout:
+                    log_notice(
+                        f"WARN: no data from {port} for {stall_timeout:.0f}s — "
+                        f"device likely hung (e.g. I2C bus lockup on the Arduino) "
+                        f"— closing after {session.row_count} rows"
+                    )
+                    session.close()
+                    return 1
                 continue
 
+            last_activity = time.monotonic()
             line = decode_line(raw)
             parsed = parse_status(line)
             if parsed:
@@ -277,6 +304,15 @@ def build_parser() -> argparse.ArgumentParser:
         default=True,
         help="Send 'log on' after connect in log mode (default: on)",
     )
+    parser.add_argument(
+        "--stall-timeout",
+        type=float,
+        default=DEFAULT_STALL_TIMEOUT_S,
+        help=(
+            "log mode: seconds without any data before treating the device as "
+            f"hung and exiting (default: {DEFAULT_STALL_TIMEOUT_S:.0f})"
+        ),
+    )
 
     subparsers = parser.add_subparsers(dest="action")
     log_p = subparsers.add_parser("log", help="Headless CSV capture", add_help=False)
@@ -285,6 +321,7 @@ def build_parser() -> argparse.ArgumentParser:
     log_p.add_argument("-o", "--output", type=Path)
     log_p.add_argument("--log-dir", type=Path, default=Path("logs"))
     log_p.add_argument("--auto-log-on", action=argparse.BooleanOptionalAction, default=True)
+    log_p.add_argument("--stall-timeout", type=float, default=DEFAULT_STALL_TIMEOUT_S)
 
     tui_p = subparsers.add_parser("tui", help="Interactive curses dashboard")
     tui_p.add_argument("-p", "--port")

src/fan_characterize.cpp

@@ -54,7 +54,7 @@ const char *FanCharacterize::phaseName() const {
 }
 
 bool FanCharacterize::start(float maxCornerC, float avgTempC) {
-  if (maxCornerC < 45.0f || maxCornerC > EMERGENCY_MAX_TEMP_C - 5.0f) {
+  if (maxCornerC < 45.0f || maxCornerC > EMERGENCY_ABSOLUTE_MAX_C - 5.0f) {
     return false;
   }
 
@@ -101,7 +101,7 @@ bool FanCharacterize::update(float avgTempC, float maxTempC, float spreadC, uint
     return false;
   }
 
-  if (maxTempC >= EMERGENCY_MAX_TEMP_C) {
+  if (maxTempC >= EMERGENCY_ABSOLUTE_MAX_C) {
     fail(F("fanchars: abort limit"));
     return false;
   }

src/main.cpp

@@ -51,6 +51,9 @@ void readAllSensors() {
     readSensorOnChannel(SENSOR_CHANNELS[i], sensors[i]);
   }
   mux.disableAll();
+  if (Wire.getWireTimeoutFlag()) {
+    Wire.clearWireTimeoutFlag();
+  }
 }
 
 float averageValidTemperature() {
@@ -437,7 +440,7 @@ void processSerialLine(const char *line) {
       maxC = atof(line + 9);
     }
 
-    if (maxC < 45.0f || maxC > EMERGENCY_MAX_TEMP_C - 5.0f) {
+    if (maxC < 45.0f || maxC > EMERGENCY_ABSOLUTE_MAX_C - 5.0f) {
       Serial.println(F("ERR fanchars max 45-65 C"));
       return;
     }
@@ -521,6 +524,11 @@ void setup() {
   }
 
   Wire.begin();
+  // Without a timeout, a glitched I2C transaction (electrical noise, a
+  // momentary bad connection) can hang the AVR's Wire library forever,
+  // freezing the whole sketch. This bounds any transaction and resets the
+  // TWI hardware so the loop keeps running instead of locking up silently.
+  Wire.setWireTimeout(I2C_TIMEOUT_US, true);
 
   if (!mux.begin()) {
     Serial.println(F("ERROR: TCA9548A not found on I2C bus"));