TempSensors.h

/*
  TempSensors.h
  ---------------------------------------------------------------------------
  Non-blocking DS18B20 reader.

  Reports raw sensor values only. All correction happens in the collector -
  see TempConfig.h for why.

  USAGE
    tempSensors.begin();                       // once, in setup()
    tempSensors.update(motorIsRunning);        // every loop pass

  update() does at most one 1-Wire transaction per call and never waits for a
  conversion, so the main loop keeps feeding the current sampler.

  Sensors are indexed in 1-Wire address order, which is stable across reboots,
  so index 0 is always the same physical probe.
*/

#ifndef TEMP_SENSORS_H
#define TEMP_SENSORS_H

#include <Arduino.h>
#include "TempConfig.h"

class TempSensors {
 public:
  void begin();

  // Call every loop pass. At most one bus transaction happens per call, and
  // reads are spaced TEMP_READ_SPACING_MS apart so they land in different
  // telemetry windows. motorRunning suspends bus traffic entirely when the
  // TEMP_READ_DURING_RUN policy says to.
  void update(bool motorRunning);

  uint8_t count() const { return count_; }
  bool enabled() const { return TEMP_ENABLED && count_ > 0; }

  bool valid(uint8_t index) const;
  float celsius(uint8_t index) const;        // raw, exactly as the sensor read
  unsigned long ageMs(uint8_t index) const;  // since this sensor last read
  const char* address(uint8_t index) const;  // 16-char hex ROM code
  const char* label(uint8_t index) const;    // where this probe is installed

  // Time the last 1-Wire transaction took, for verifying it is not starving
  // the current sampler.
  unsigned long lastBusMicros() const { return lastBusMicros_; }
  unsigned long busyMicrosThisWindow();     // reads and clears the accumulator

  bool conversionPending() const { return state_ == State::CONVERTING; }

  // The hardware GPIO the bus actually ended up on, after pin remapping.
  uint8_t gpio() const { return gpio_; }
  unsigned long lastCycleAtMs() const { return lastCycleAtMs_; }

 private:
  enum class State : uint8_t { IDLE, CONVERTING, READING };

  void discover();
  void startConversion();
  void readOne();

  State state_ = State::IDLE;

  uint8_t count_ = 0;
  uint8_t readIndex_ = 0;

  float rawC_[TEMP_MAX_SENSORS];
  bool valid_[TEMP_MAX_SENSORS];
  unsigned long readAtMs_[TEMP_MAX_SENSORS];
  char addressHex_[TEMP_MAX_SENSORS][17];

  unsigned long lastCycleAtMs_ = 0;
  unsigned long conversionStartedAtMs_ = 0;
  unsigned long conversionWaitMs_ = 750;

  uint8_t gpio_ = 0;
  unsigned long lastRescanAtMs_ = 0;
  unsigned long lastReadAtMs_ = 0;
  unsigned long lastBusMicros_ = 0;
  unsigned long busyMicrosAccum_ = 0;
};

extern TempSensors tempSensors;

float celsiusToFahrenheit(float celsius);
float fahrenheitToCelsius(float fahrenheit);

#endif  // TEMP_SENSORS_H