remove fan-controls

README.md

@@ -82,20 +82,14 @@ Verify access: `test -w /dev/ttyUSB0 && echo ok`
 
 1. Flash firmware and open the serial monitor at 115200 baud.
 2. Confirm `TCA9548A detected` and four valid sensor channels (`ch2`–`ch5`).
-3. Find **stir fan** speed (chamber ~35°C, idle):
+3. Find **stir fan** speed (optional — default is **PWM 178**, ~70%):
 
    ```
    target 0
    fanchars
    ```
 
-   Heats to max **60°C** at **30%, 100%, 60%, 80%** fan (cool to **40°C** avg between each). If the best is not at 30% or 100%, runs once at the midpoint of the two lowest spreads (~1–3 h). Or: `python3 scripts/fan_characterize.py`. When done:
+   Sweeps **30%, 100%, 60%, 80%** fan — heats to max **60°C** corner at **100%** heater. Cools to **40°C** avg between runs. Skips a fan speed if 60°C isn't reached in time. Optional midpoint refine if best isn't at 30% or 100%. Or: `python3 scripts/fan_characterize.py`. When done, `fanchars save` writes the winner to EEPROM (or skip and keep the 178 default).
-
-   ```
-   fanchars save
-   ```
-
-   Stored PWM is the minimum-stir floor while regulating (≥40°C avg).
 
 4. Tune **heat PI** (stored in EEPROM on autotune complete):
 
@@ -107,9 +101,9 @@ Verify access: `test -w /dev/ttyUSB0 && echo ok`
 
    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.
 
-5. Optional: adjust **mix PI** at target if spread still drifts (`mixpi`, `pid save`). Stir fan from step 3 is usually enough to start drying.
+5. Dry at your target — fan runs at the stir PWM (default **178**) unless you override with `fan <pwm>`; `fan auto` returns to the default.
 
-Send `help` over serial for all commands (`target`, `fanchars`, `mixpi`, `fan test`, `log on/off`, `status`, `pid`, etc.).
+Send `help` over serial for all commands (`target`, `fanchars`, `fan`, `log on/off`, `status`, `pid`, etc.).
 
 ## Raspberry Pi control
 

include/config.h

@@ -29,16 +29,12 @@ static const float TARGET_MAX_C = 80.0f;
 static const float EMERGENCY_MAX_TEMP_C = 70.0f;
 static const float CORNER_STOP_MARGIN_C = 3.0f;
 
-// Dual PI — heat on avg, mix on spread (no D term)
+// Heat PI on average temp (no D term)
 static const float HEAT_PI_KP = 4.0f;
 static const float HEAT_PI_KI = 0.05f;
-static const float MIX_PI_KP = 40.0f;
+
-static const float MIX_PI_KI = 2.0f;
+// Fixed circulation fan (~70%, fanchars winner); override with "fan <pwm>" when regulating
-static const float SPREAD_TARGET_C = 0.5f;
+static const uint8_t FAN_STIR_PWM = 178;
-static const float HEAT_UP_BAND_C = 8.0f;
-// Mix PI only at/above target; below target use minimum stir only (no mix PI).
-// Cap mix fan — high airflow often increases spread / heat loss rather than fixing it.
-static const uint8_t FAN_MIX_MAX_PWM = 140;
 
 // Legacy aliases for autotuner relay math only
 static const float PID_KP = HEAT_PI_KP;
@@ -81,7 +77,7 @@ static const uint32_t AUTOTUNE_RELAY_PERIOD_MAX_MS = 2400000UL;
 static const float FANCHARS_MAX_CORNER_C = 60.0f;
 static const float FANCHARS_COOL_AVG_C = 40.0f;
 static const float FANCHARS_PRECOOL_MARGIN_C = 2.0f;
-static const float FANCHARS_HEATER_PCT = 85.0f;
+static const float FANCHARS_HEATER_PCT = 100.0f;
 // Coarse sweep order: 30%, 100%, 60%, 80% fan
 static const uint8_t FANCHARS_COARSE_PWM[] = {77, 255, 153, 204};
 static const uint8_t FANCHARS_COARSE_COUNT =

include/pid_autotuner.h

@@ -271,7 +271,7 @@ private:
     Serial.print(resultKp_, 3);
     Serial.print(F(" Ki="));
     Serial.println(resultKi_, 4);
-    Serial.println(F("  tune mix PI separately: mixpi <Kp> <Ki>"));
+    Serial.println(F("  tune heat PI: pid save after autotune"));
   }
 
   void fail(const __FlashStringHelper *reason) {

include/settings_store.h

@@ -12,7 +12,7 @@ static const int SETTINGS_EEPROM_ADDR = 16;
 struct SettingsData {
   uint16_t magic = 0;
   float targetC = TARGET_TEMP_C;
-  uint8_t stirFanPwm = 0; // 0 = use FAN_IDLE_PWM (~30%)
+  uint8_t stirFanPwm = 0; // 0 = use FAN_STIR_PWM from config
 };
 
 inline uint8_t settingsChecksum(const SettingsData &data) {

include/thermal_controller.h

@@ -15,7 +15,6 @@ public:
 
   ThermalController()
       : heatPi_(HEAT_PI_KP, HEAT_PI_KI, 0.0f, 0.0f, 100.0f),
-        mixPi_(MIX_PI_KP, MIX_PI_KI, 0.0f, 0.0f, 255.0f),
         autotuner_(),
         fanchars_(),
         targetTempC_(TARGET_TEMP_C),
@@ -24,10 +23,12 @@ public:
         cornerSpreadC_(0.0f),
         lastMaxTempC_(0.0f),
         regulatingFanPwm_(0),
-        stirFanPwm_(FAN_IDLE_PWM),
+        stirFanPwm_(FAN_STIR_PWM),
+        fanManualPwm_(0),
         fanPwm_(0),
         tuningLoaded_(false),
         fanIdleOverride_(false),
+        fanManualActive_(false),
         sensorWarmValid_(false),
         cutoffActive_(false),
         failSafeActive_(true),
@@ -38,9 +39,7 @@ public:
         heaterBlock_(HeaterBlock::None),
         fanTestActive_(false),
         fanTestPwm_(0),
-        fanTestEndMs_(0) {
+        fanTestEndMs_(0) {}
-    mixPi_.setSetpoint(0.0f);
-  }
 
   void begin() {
     pinMode(FAN_PIN, OUTPUT);
@@ -50,7 +49,6 @@ public:
 
     heatPi_.setSetpoint(targetTempC_);
     heatPi_.reset();
-    mixPi_.reset();
     heaterCycleStartMs_ = millis();
     lastHeaterUpdateMs_ = 0;
     failSafeActive_ = true;
@@ -83,44 +81,22 @@ public:
 
   void applyTuning(const TuningData &data) {
     heatPi_.setTunings(data.heatKp, data.heatKi, 0.0f);
-    mixPi_.setTunings(data.mixKp, data.mixKi, 0.0f);
     tuningLoaded_ = true;
   }
 
   void clearTuning() {
     tuningLoaded_ = false;
     heatPi_.setTunings(HEAT_PI_KP, HEAT_PI_KI, 0.0f);
-    mixPi_.setTunings(MIX_PI_KP, MIX_PI_KI, 0.0f);
     tuningClear();
     heatPi_.reset();
-    mixPi_.reset();
     Serial.println(F("PI reset to defaults"));
   }
 
-  void setMixTunings(float kp, float ki) {
-    mixPi_.setTunings(kp, ki, 0.0f);
-    mixPi_.reset();
-    Serial.print(F("Mix PI Kp="));
-    Serial.print(kp, 3);
-    Serial.print(F(" Ki="));
-    Serial.println(ki, 4);
-  }
-
-  void resetMixTunings() {
-    mixPi_.setTunings(MIX_PI_KP, MIX_PI_KI, 0.0f);
-    mixPi_.reset();
-    Serial.println(F("Mix PI reset to defaults"));
-  }
-
   void printTuning() const {
     Serial.print(F("Heat PI Kp="));
     Serial.print(heatPi_.kp(), 3);
     Serial.print(F(" Ki="));
     Serial.print(heatPi_.ki(), 4);
-    Serial.print(F("  Mix PI Kp="));
-    Serial.print(mixPi_.kp(), 3);
-    Serial.print(F(" Ki="));
-    Serial.print(mixPi_.ki(), 4);
     Serial.print(F("  tuned="));
     Serial.println(tuningLoaded_ ? F("yes") : F("no"));
   }
@@ -130,8 +106,6 @@ public:
     data.magic = TUNING_MAGIC;
     data.heatKp = heatPi_.kp();
     data.heatKi = heatPi_.ki();
-    data.mixKp = mixPi_.kp();
-    data.mixKi = mixPi_.ki();
     tuningSave(data);
     tuningLoaded_ = true;
     Serial.println(F("Saved PI to EEPROM"));
@@ -139,8 +113,6 @@ public:
 
   float heatKp() const { return heatPi_.kp(); }
   float heatKi() const { return heatPi_.ki(); }
-  float mixKp() const { return mixPi_.kp(); }
-  float mixKi() const { return mixPi_.ki(); }
 
   bool isTuningLoaded() const { return tuningLoaded_; }
 
@@ -150,7 +122,6 @@ public:
     }
     cutoffActive_ = false;
     heatPi_.reset();
-    mixPi_.reset();
     return autotuner_.start(setpointC);
   }
 
@@ -175,7 +146,6 @@ public:
     stopFanTest();
     cutoffActive_ = false;
     heatPi_.reset();
-    mixPi_.reset();
     setTarget(0.0f, false);
     return fanchars_.start(maxCornerC, avgTempC);
   }
@@ -204,6 +174,32 @@ public:
 
   uint8_t stirFanPwm() const { return stirFanPwm_; }
 
+  bool isFanManualOverride() const { return fanManualActive_ && !isIdle(); }
+
+  bool setRegulatingFanManual(uint8_t pwm) {
+    if (isIdle()) {
+      return false;
+    }
+    fanManualPwm_ = pwm;
+    fanManualActive_ = true;
+    return true;
+  }
+
+  void clearRegulatingFanManual() {
+    fanManualActive_ = false;
+  }
+
+  bool setStirFanPwm(uint8_t pwm, bool persist = true) {
+    if (pwm == 0) {
+      return false;
+    }
+    stirFanPwm_ = pwm;
+    if (persist) {
+      settingsSaveStirFan(pwm);
+    }
+    return true;
+  }
+
   void logFanCharacterizeIfDue(const float *sensorTemps, const bool *sensorValid, uint8_t sensorCount,
                                float avgTempC, float minTempC, float maxTempC, float spreadC,
                                uint32_t nowMs) {
@@ -239,12 +235,10 @@ public:
     data.magic = TUNING_MAGIC;
     data.heatKp = autotuner_.resultKp();
     data.heatKi = autotuner_.resultKi();
-    data.mixKp = mixPi_.kp();
-    data.mixKi = mixPi_.ki();
     tuningSave(data);
     tuningLoaded_ = true;
     autotuner_.reset();
-    Serial.println(F("Saved heat PI to EEPROM (mix PI unchanged)"));
+    Serial.println(F("Saved heat PI to EEPROM"));
     return true;
   }
 
@@ -252,7 +246,7 @@ public:
     targetTempC_ = targetC;
     heatPi_.setSetpoint(targetC);
     heatPi_.reset();
-    mixPi_.reset();
+    fanManualActive_ = false;
     cutoffActive_ = false;
     if (targetC > 0.0f) {
       fanIdleOverride_ = false;
@@ -390,7 +384,6 @@ public:
       forceHeaterOff();
       cutoffActive_ = false;
       heatPi_.reset();
-      mixPi_.reset();
       lastHeaterUpdateMs_ = nowMs;
       applyFan(nowMs);
       return;
@@ -408,7 +401,6 @@ public:
     forceHeaterOff();
     applyFan(millis());
     heatPi_.reset();
-    mixPi_.reset();
     autotuner_.abort();
     fanchars_.abort();
   }
@@ -485,14 +477,12 @@ private:
       regulatingFanPwm_ = FAN_MAX_PWM;
       heaterBlock_ = HeaterBlock::Cutoff;
       heatPi_.reset();
-      mixPi_.reset();
       return;
     }
 
     if (cutoffActive_ && maxTempC < EMERGENCY_MAX_TEMP_C - 5.0f) {
       cutoffActive_ = false;
       heatPi_.reset();
-      mixPi_.reset();
     }
 
     if (cutoffActive_) {
@@ -523,17 +513,7 @@ private:
     }
     heaterDutyPercent_ = applyHeaterRamp(duty, avgTempC, nowMs);
 
-    uint8_t fanPwm = stirFanPwm_;
+    const uint8_t fanPwm = fanManualActive_ ? fanManualPwm_ : stirFanPwm_;
-    if (avgTempC < targetTempC_) {
-      mixPi_.reset();
-    } else {
-      const float mixInput = SPREAD_TARGET_C - cornerSpreadC_;
-      float fanOut = mixPi_.compute(mixInput, nowMs);
-      fanPwm = static_cast<uint8_t>(fanOut + 0.5f);
-      if (fanPwm > FAN_MIX_MAX_PWM) {
-        fanPwm = FAN_MIX_MAX_PWM;
-      }
-    }
     regulatingFanPwm_ = fanWithMinStir(avgTempC, fanPwm);
   }
 
@@ -541,9 +521,6 @@ private:
     if (avgTempC < IDLE_AUTO_FAN_OFF_TEMP_C) {
       return 0;
     }
-    if (pwm < stirFanPwm_) {
-      return stirFanPwm_;
-    }
     return pwm;
   }
 
@@ -665,7 +642,6 @@ private:
   }
 
   PidController heatPi_;
-  PidController mixPi_;
   PidAutotuner autotuner_;
   FanCharacterize fanchars_;
   float targetTempC_;
@@ -675,9 +651,11 @@ private:
   float lastMaxTempC_;
   uint8_t regulatingFanPwm_;
   uint8_t stirFanPwm_;
+  uint8_t fanManualPwm_;
   uint8_t fanPwm_;
   bool tuningLoaded_;
   bool fanIdleOverride_;
+  bool fanManualActive_;
   bool sensorWarmValid_;
   bool cutoffActive_;
   bool failSafeActive_;

include/tuning_store.h

@@ -5,15 +5,13 @@
 
 #include "config.h"
 
-static const uint16_t TUNING_MAGIC = 0xDA7B;
+static const uint16_t TUNING_MAGIC = 0xDA7C;
 static const int TUNING_EEPROM_ADDR = 0;
 
 struct TuningData {
   uint16_t magic = 0;
   float heatKp = HEAT_PI_KP;
   float heatKi = HEAT_PI_KI;
-  float mixKp = MIX_PI_KP;
-  float mixKi = MIX_PI_KI;
 };
 
 inline uint8_t tuningChecksum(const TuningData &data) {

scripts/dryer_tui.py

@@ -200,7 +200,9 @@ def apply_status(state: DryerState, data: dict) -> None:
     fan_raw = data["fan"]
     state.fan = format_fan_display(fan_raw)
     state.fan_note = ""
-    if "(off)" in fan_raw or "(cooldown)" in fan_raw or "(cmd-off)" in fan_raw:
+    if "(off)" in fan_raw or "(cooldown)" in fan_raw or "(off<40C)" in fan_raw:
+        state.fan_note = fan_raw[fan_raw.find("(") :] if "(" in fan_raw else ""
+    elif "(manual)" in fan_raw or "(stir)" in fan_raw:
         state.fan_note = fan_raw[fan_raw.find("(") :] if "(" in fan_raw else ""
     elif "(fanchars-" in fan_raw:
         state.fan_note = fan_raw[fan_raw.find("(fanchars-") :]

src/main.cpp

@@ -150,8 +150,12 @@ void printStatus(float avgTemp, float minTemp, float maxTemp) {
     Serial.print(F("(off)"));
   } else if (thermal.isIdleCooling()) {
     Serial.print(F("(cooldown)"));
-  } else if (thermal.fanPwm() == 0) {
+  } else if (thermal.isFanManualOverride()) {
-    Serial.print(F("(cmd-off)"));
+    Serial.print(F("(manual)"));
+  } else if (!thermal.isIdle() && thermal.fanPwm() == 0) {
+    Serial.print(F("(off<40C)"));
+  } else if (!thermal.isIdle()) {
+    Serial.print(F("(stir)"));
   }
   Serial.print(F(" cutoff="));
   Serial.print(thermal.isCutoffActive() ? F("YES") : F("no"));
@@ -224,17 +228,18 @@ void printHelp() {
   Serial.println(F("  target <C>  set target (0 = idle)"));
   Serial.println(F("  fan off     cancel idle fan override (auto-off below 40C)"));
   Serial.println(F("  fan on      idle fan 30% (optional, auto-off below 40C)"));
+  Serial.println(F("  fan auto    regulating: back to default stir fan"));
+  Serial.println(F("  fan <pwm>   regulating: manual fan override (0-255)"));
+  Serial.println(F("  fan stir    show default stir fan PWM"));
+  Serial.println(F("  fan stir N  set default stir fan + EEPROM"));
   Serial.println(F("  fan test N  set fan PWM 0-255 for 15s (verify wiring)"));
   Serial.println(F("  autotune [C] learn heat PI (default: 40C when idle)"));
   Serial.println(F("  autotune stop"));
   Serial.println(F("  fanchars      learn stir fan (30/100/60/80%% + refine)"));
   Serial.println(F("  fanchars stop | fanchars save"));
-  Serial.println(F("  pid         show heat + mix PI gains"));
+  Serial.println(F("  pid         show heat PI gains"));
-  Serial.println(F("  pid default reset all PI to factory"));
+  Serial.println(F("  pid default reset heat PI to factory"));
   Serial.println(F("  pid save    write current PI to EEPROM"));
-  Serial.println(F("  mixpi       show mix PI gains"));
-  Serial.println(F("  mixpi <Kp> <Ki>  set mix PI (spread -> fan)"));
-  Serial.println(F("  mixpi default    reset mix PI to factory"));
   Serial.println(F("  status      print current readings"));
   Serial.println(F("  log on|off  CSV data stream"));
   Serial.println(F("  help        show this message"));
@@ -323,6 +328,58 @@ void processSerialLine(const char *line) {
     return;
   }
 
+  if (strcmp(line, "fan auto") == 0) {
+    if (thermal.isIdle()) {
+      Serial.println(F("ERR fan auto only when regulating (set target > 0)"));
+      return;
+    }
+    thermal.clearRegulatingFanManual();
+    Serial.print(F("OK fan stir "));
+    Serial.println(thermal.stirFanPwm());
+    return;
+  }
+
+  if (strncmp(line, "fan stir", 8) == 0) {
+    if (line[8] == '\0') {
+      Serial.print(F("stir fan PWM="));
+      Serial.println(thermal.stirFanPwm());
+      return;
+    }
+    if (line[8] == ' ') {
+      const int pwm = atoi(line + 9);
+      if (pwm < 1 || pwm > 255) {
+        Serial.println(F("ERR fan stir PWM must be 1-255"));
+        return;
+      }
+      thermal.setStirFanPwm(static_cast<uint8_t>(pwm));
+      if (!thermal.isIdle()) {
+        thermal.clearRegulatingFanManual();
+      }
+      Serial.print(F("OK stir fan "));
+      Serial.println(pwm);
+      return;
+    }
+  }
+
+  if (strncmp(line, "fan ", 4) == 0) {
+    const char *arg = line + 4;
+    if (*arg >= '0' && *arg <= '9') {
+      const int pwm = atoi(arg);
+      if (pwm < 0 || pwm > 255) {
+        Serial.println(F("ERR fan PWM must be 0-255"));
+        return;
+      }
+      if (thermal.isIdle()) {
+        Serial.println(F("ERR fan <pwm> only when regulating (or use fan test)"));
+        return;
+      }
+      thermal.setRegulatingFanManual(static_cast<uint8_t>(pwm));
+      Serial.print(F("OK fan manual "));
+      Serial.println(pwm);
+      return;
+    }
+  }
+
   if (strcmp(line, "status") == 0) {
     const float avgTemp = averageValidTemperature();
     const float minTemp = minValidTemperature();
@@ -415,35 +472,6 @@ void processSerialLine(const char *line) {
     return;
   }
 
-  if (strcmp(line, "mixpi") == 0 || strcmp(line, "mixpi show") == 0) {
-    Serial.print(F("Mix PI Kp="));
-    Serial.print(thermal.mixKp(), 3);
-    Serial.print(F(" Ki="));
-    Serial.println(thermal.mixKi(), 4);
-    return;
-  }
-
-  if (strcmp(line, "mixpi default") == 0) {
-    thermal.resetMixTunings();
-    return;
-  }
-
-  if (strncmp(line, "mixpi ", 6) == 0) {
-    const float kp = atof(line + 6);
-    const char *space = strchr(line + 6, ' ');
-    if (space == nullptr) {
-      Serial.println(F("ERR mixpi requires: mixpi <Kp> <Ki>"));
-      return;
-    }
-    const float ki = atof(space + 1);
-    if (kp <= 0.0f || ki < 0.0f) {
-      Serial.println(F("ERR mixpi Kp must be > 0, Ki >= 0"));
-      return;
-    }
-    thermal.setMixTunings(kp, ki);
-    return;
-  }
-
   if (strcmp(line, "help") == 0) {
     printHelp();
     return;