🐛 Fix and improve MAX31865 (#23215)

Co-authored-by: Scott Lahteine <thinkyhead@users.noreply.github.com>

Marlin/Configuration_adv.h

@@ -142,11 +142,20 @@
  *   FORCE_HW_SPI:   Ignore SCK/MOSI/MISO pins and just use the CS pin & default SPI bus.
  *   MAX31865_WIRES: Set the number of wires for the probe connected to a MAX31865 board, 2-4. Default: 2
  *   MAX31865_50HZ:  Enable 50Hz filter instead of the default 60Hz.
+ *   MAX31865_USE_READ_ERROR_DETECTION: Detects random read errors from value spikes (a 20°C difference in less than 1sec)
+ *   MAX31865_USE_AUTO_MODE: Faster and more frequent reads than 1-shot, but bias voltage always on, slightly affecting RTD temperature.
+ *   MAX31865_MIN_SAMPLING_TIME_MSEC: in 1-shot mode, the minimum time between subsequent reads. This reduces the effect of bias voltage by leaving the sensor unpowered for longer intervals.
+ *   MAX31865_WIRE_OHMS: In 2-wire configurations, manually set the wire resistance for more accurate readings
  */
 //#define TEMP_SENSOR_FORCE_HW_SPI
 //#define MAX31865_SENSOR_WIRES_0 2
 //#define MAX31865_SENSOR_WIRES_1 2
 //#define MAX31865_50HZ_FILTER
+//#define MAX31865_USE_READ_ERROR_DETECTION
+//#define MAX31865_USE_AUTO_MODE
+//#define MAX31865_MIN_SAMPLING_TIME_MSEC 100
+//#define MAX31865_WIRE_OHMS_0 0.0f
+//#define MAX31865_WIRE_OHMS_1 0.0f
 
 /**
  * Hephestos 2 24V heated bed upgrade kit.

Marlin/src/inc/Conditionals_adv.h

@@ -159,6 +159,9 @@
     #ifndef MAX31865_SENSOR_WIRES_0
       #define MAX31865_SENSOR_WIRES_0 2
     #endif
+    #ifndef MAX31865_WIRE_OHMS_0
+      #define MAX31865_WIRE_OHMS_0 0.0f
+    #endif
   #elif TEMP_SENSOR_0 == -3
     #define TEMP_SENSOR_0_IS_MAX31855 1
     #define TEMP_SENSOR_0_MAX_TC_TMIN -270
@@ -193,6 +196,9 @@
     #ifndef MAX31865_SENSOR_WIRES_1
       #define MAX31865_SENSOR_WIRES_1 2
     #endif
+    #ifndef MAX31865_WIRE_OHMS_1
+      #define MAX31865_WIRE_OHMS_1 0.0f
+    #endif
   #elif TEMP_SENSOR_1 == -3
     #define TEMP_SENSOR_1_IS_MAX31855 1
     #define TEMP_SENSOR_1_MAX_TC_TMIN -270

Marlin/src/libs/MAX31865.cpp

@@ -40,20 +40,23 @@
  * All rights reserved.
  */
 
-// Useful for RTD debugging.
-//#define MAX31865_DEBUG
-//#define MAX31865_DEBUG_SPI
-
 #include "../inc/MarlinConfig.h"
 
 #if HAS_MAX31865 && !USE_ADAFRUIT_MAX31865
 
 #include "MAX31865.h"
 
+#ifndef MAX31865_MIN_SAMPLING_TIME_MSEC
+  #define MAX31865_MIN_SAMPLING_TIME_MSEC 0
+#endif
+
 #ifdef TARGET_LPC1768
   #include <SoftwareSPI.h>
 #endif
 
+#define DEBUG_OUT ENABLED(DEBUG_MAX31865)
+#include "../core/debug_out.h"
+
 // The maximum speed the MAX31865 can do is 5 MHz
 SPISettings MAX31865::spiConfig = SPISettings(
   TERN(TARGET_LPC1768, SPI_QUARTER_SPEED, TERN(ARDUINO_ARCH_STM32, SPI_CLOCK_DIV4, 500000)),
@@ -61,7 +64,7 @@ SPISettings MAX31865::spiConfig = SPISettings(
   SPI_MODE1 // CPOL0 CPHA1
 );
 
-#ifndef LARGE_PINMAP
+#if DISABLED(LARGE_PINMAP)
 
   /**
    * Create the interface object using software (bitbang) SPI for PIN values
@@ -137,117 +140,121 @@ SPISettings MAX31865::spiConfig = SPISettings(
  * @param wires  The number of wires in enum format. Can be MAX31865_2WIRE, MAX31865_3WIRE, or MAX31865_4WIRE.
  * @param zero   The resistance of the RTD at 0 degC, in ohms.
  * @param ref    The resistance of the reference resistor, in ohms.
+ * @param wire   The resistance of the wire connecting the sensor to the RTD, in ohms.
  */
-void MAX31865::begin(max31865_numwires_t wires, float zero, float ref) {
-  zeroRes = zero;
-  refRes = ref;
+void MAX31865::begin(max31865_numwires_t wires, float zero_res, float ref_res, float wire_res) {
+  zeroRes = zero_res;
+  refRes = ref_res;
+  wireRes = wire_res;
 
-  OUT_WRITE(cselPin, HIGH);
+  pinMode(cselPin, OUTPUT);
+  digitalWrite(cselPin, HIGH);
 
-  if (sclkPin != TERN(LARGE_PINMAP, -1UL, -1)) {
+  if (sclkPin != TERN(LARGE_PINMAP, -1UL, 255))
     softSpiBegin(SPI_QUARTER_SPEED); // Define pin modes for Software SPI
-  }
   else {
-    #ifdef MAX31865_DEBUG
-      SERIAL_ECHOLNPGM("Initializing MAX31865 Hardware SPI");
-    #endif
+    DEBUG_ECHOLNPGM("Initializing MAX31865 Hardware SPI");
     SPI.begin();    // Start and configure hardware SPI
   }
 
-  setWires(wires);
-  enableBias(false);
-  autoConvert(false);
-  clearFault();
-
-  #ifdef MAX31865_DEBUG_SPI
-    SERIAL_ECHOLNPGM(
-      TERN(LARGE_PINMAP, "LARGE_PINMAP", "Regular")
-      " begin call with cselPin: ", cselPin,
-      " misoPin: ", misoPin,
-      " sclkPin: ", sclkPin,
-      " mosiPin: ", mosiPin,
-      " config: ", readRegister8(MAX31865_CONFIG_REG)
-    );
-  #endif
+  initFixedFlags(wires);
+
+  clearFault(); // also initializes flags
+
+  #if DISABLED(MAX31865_USE_AUTO_MODE) // make a proper first 1 shot read to initialize _lastRead
+
+    enableBias();
+    DELAY_US(11500);
+    oneShot();
+    DELAY_US(65000);
+    uint16_t rtd = readRegister16(MAX31865_RTDMSB_REG);
+
+    if (rtd & 1) {
+      lastRead = 0xFFFF; // some invalid value
+      lastFault = readRegister8(MAX31865_FAULTSTAT_REG);
+      clearFault(); // also clears the bias voltage flag, so no further action is required
+
+      DEBUG_ECHOLNPGM("MAX31865 read fault: ", rtd);
+    }
+    else {
+      DEBUG_ECHOLNPGM("RTD MSB:", (rtd >> 8), "  RTD LSB:", (rtd & 0x00FF));
+
+      resetFlags();
+
+      lastRead = rtd;
+      nextEvent = SETUP_BIAS_VOLTAGE;
+      millis_t now = millis();
+      nextEventStamp = now + MAX31865_MIN_SAMPLING_TIME_MSEC;
+
+      TERN_(MAX31865_USE_READ_ERROR_DETECTION, lastReadStamp = now);
+    }
+
+  #endif // !MAX31865_USE_AUTO_MODE
+
+  DEBUG_ECHOLNPGM(
+    TERN(LARGE_PINMAP, "LARGE_PINMAP", "Regular")
+    " begin call with cselPin: ", cselPin,
+    " misoPin: ", misoPin,
+    " sclkPin: ", sclkPin,
+    " mosiPin: ", mosiPin,
+    " config: ", readRegister8(MAX31865_CONFIG_REG)
+  );
 }
 
 /**
- * Read the raw 8-bit FAULTSTAT register
+ * Return and clear the last fault value
  *
- * @return The raw unsigned 8-bit FAULT status register
+ * @return The raw unsigned 8-bit FAULT status register or spike fault
  */
 uint8_t MAX31865::readFault() {
-  return readRegister8(MAX31865_FAULTSTAT_REG);
+  uint8_t r = lastFault;
+  lastFault = 0;
+  return r;
 }
 
 /**
- * Clear all faults in FAULTSTAT.
+ * Clear last fault
  */
 void MAX31865::clearFault() {
   setConfig(MAX31865_CONFIG_FAULTSTAT, 1);
 }
 
 /**
- * Whether we want to have continuous conversions (50/60 Hz)
- *
- * @param b  If true, auto conversion is enabled
- */
-void MAX31865::autoConvert(bool b) {
-  setConfig(MAX31865_CONFIG_MODEAUTO, b);
-}
-
-/**
- * Whether we want filter out 50Hz noise or 60Hz noise
- *
- * @param b  If true, 50Hz noise is filtered, else 60Hz(default)
+ * Reset flags
  */
-void MAX31865::enable50HzFilter(bool b) {
-  setConfig(MAX31865_CONFIG_FILT50HZ, b);
+void MAX31865::resetFlags() {
+  writeRegister8(MAX31865_CONFIG_REG, stdFlags);
 }
 
 /**
  * Enable the bias voltage on the RTD sensor
- *
- * @param b  If true bias is enabled, else disabled
  */
-void MAX31865::enableBias(bool b) {
-  setConfig(MAX31865_CONFIG_BIAS, b);
-
-  // From the datasheet:
-  // Note that if VBIAS is off (to reduce supply current between conversions), any filter
-  // capacitors at the RTDIN inputs need to charge before an accurate conversion can be
-  // performed. Therefore, enable VBIAS and wait at least 10.5 time constants of the input
-  // RC network plus an additional 1ms before initiating the conversion.
-  if (b)
-    DELAY_US(11500); //11.5ms
+void MAX31865::enableBias() {
+  setConfig(MAX31865_CONFIG_BIAS, 1);
 }
 
 /**
  * Start a one-shot temperature reading.
  */
 void MAX31865::oneShot() {
-  setConfig(MAX31865_CONFIG_1SHOT, 1);
-
-  // From the datasheet:
-  // Note that a single conversion requires approximately 52ms in 60Hz filter
-  // mode or 62.5ms in 50Hz filter mode to complete. 1-Shot is a self-clearing bit.
-  // TODO: switch this out depending on the filter mode.
-  DELAY_US(65000); // 65ms
+  setConfig(MAX31865_CONFIG_1SHOT | MAX31865_CONFIG_BIAS, 1);
 }
 
 /**
- * How many wires we have in our RTD setup, can be MAX31865_2WIRE,
- * MAX31865_3WIRE, or MAX31865_4WIRE
+ * Initialize standard flags with flags that will not change during operation (Hz, polling mode and no. of wires)
  *
  * @param wires The number of wires in enum format
  */
-void MAX31865::setWires(max31865_numwires_t wires) {
-  uint8_t t = readRegister8(MAX31865_CONFIG_REG);
+void MAX31865::initFixedFlags(max31865_numwires_t wires) {
+
+  // set config-defined flags (same for all sensors)
+  stdFlags = TERN(MAX31865_50HZ_FILTER, MAX31865_CONFIG_FILT50HZ, MAX31865_CONFIG_FILT60HZ) |
+              TERN(MAX31865_USE_AUTO_MODE, MAX31865_CONFIG_MODEAUTO | MAX31865_CONFIG_BIAS, MAX31865_CONFIG_MODEOFF);
+
   if (wires == MAX31865_3WIRE)
-    t |= MAX31865_CONFIG_3WIRE;
-  else // 2 or 4 wire
-    t &= ~MAX31865_CONFIG_3WIRE;
-  writeRegister8(MAX31865_CONFIG_REG, t);
+    stdFlags |= MAX31865_CONFIG_3WIRE;
+  else  // 2 or 4 wire
+    stdFlags &= ~MAX31865_CONFIG_3WIRE;
 }
 
 /**
@@ -257,33 +264,96 @@ void MAX31865::setWires(max31865_numwires_t wires) {
  * @return The raw unsigned 16-bit register value with ERROR bit attached, NOT temperature!
  */
 uint16_t MAX31865::readRaw() {
-  clearFault();
-  enableBias(true);
 
-  oneShot();
-  uint16_t rtd = readRegister16(MAX31865_RTDMSB_REG);
+  #if ENABLED(MAX31865_USE_AUTO_MODE)
 
-  #ifdef MAX31865_DEBUG
-    SERIAL_ECHOLNPGM("RTD MSB:", (rtd >> 8), "  RTD LSB:", (rtd & 0x00FF));
-  #endif
+    const uint16_t rtd = readRegister16(MAX31865_RTDMSB_REG);
+    DEBUG_ECHOLNPGM("MAX31865 RTD MSB:", (rtd >> 8), " LSB:", (rtd & 0x00FF));
+
+    if (rtd & 1) {
+      lastFault = readRegister8(MAX31865_FAULTSTAT_REG);
+      lastRead |= 1;
+      clearFault(); // also clears the bias voltage flag, so no further action is required
+      DEBUG_ECHOLNPGM("MAX31865 read fault: ", rtd);
+    }
+    #if ENABLED(MAX31865_USE_READ_ERROR_DETECTION)
+      else if (ABS(lastRead - rtd) > 500 && PENDING(millis(), lastReadStamp + 1000)) { // if two readings within a second differ too much (~20°C), consider it a read error.
+        lastFault = 0x01;
+        lastRead |= 1;
+        DEBUG_ECHOLNPGM("MAX31865 read error: ", rtd);
+      }
+    #endif
+    else {
+      lastRead = rtd;
+      TERN_(MAX31865_USE_READ_ERROR_DETECTION, lastReadStamp = millis());
+    }
 
-  // Disable the bias to lower power dissipation between reads.
-  // If the ref resistor heats up, the temperature reading will be skewed.
-  enableBias(false);
+  #else
+
+    if (PENDING(millis(), nextEventStamp)) {
+      DEBUG_ECHOLNPGM("MAX31865 waiting for event ", nextEvent);
+      return lastRead;
+    }
+
+    switch (nextEvent) {
+      case SETUP_BIAS_VOLTAGE:
+        enableBias();
+        nextEventStamp = millis() + 11; // wait at least 11msec before enabling 1shot
+        nextEvent = SETUP_1_SHOT_MODE;
+        DEBUG_ECHOLN("MAX31865 bias voltage enabled");
+        break;
+
+      case SETUP_1_SHOT_MODE:
+        oneShot();
+        nextEventStamp = millis() + 65; // wait at least 65msec before reading RTD register
+        nextEvent = READ_RTD_REG;
+        DEBUG_ECHOLN("MAX31865 1 shot mode enabled");
+        break;
+
+      case READ_RTD_REG: {
+        const uint16_t rtd = readRegister16(MAX31865_RTDMSB_REG);
+        DEBUG_ECHOLNPGM("MAX31865 RTD MSB:", (rtd >> 8), " LSB:", (rtd & 0x00FF));
+
+        if (rtd & 1) {
+          lastFault = readRegister8(MAX31865_FAULTSTAT_REG);
+          lastRead |= 1;
+          clearFault(); // also clears the bias voltage flag, so no further action is required
+          DEBUG_ECHOLNPGM("MAX31865 read fault: ", rtd);
+        }
+        #if ENABLED(MAX31865_USE_READ_ERROR_DETECTION)
+          else if (ABS(lastRead - rtd) > 500 && PENDING(millis(), lastReadStamp + 1000)) { // if two readings within a second differ too much (~20°C), consider it a read error.
+            lastFault = 0x01;
+            lastRead |= 1;
+            DEBUG_ECHOLNPGM("MAX31865 read error: ", rtd);
+          }
+        #endif
+        else {
+          lastRead = rtd;
+          TERN_(MAX31865_USE_READ_ERROR_DETECTION, lastReadStamp = millis());
+        }
+
+        if (!(rtd & 1))   // if clearFault() was not invoked, need to clear the bias voltage and 1-shot flags
+          resetFlags();
+
+        nextEvent = SETUP_BIAS_VOLTAGE;
+        nextEventStamp = millis() + MAX31865_MIN_SAMPLING_TIME_MSEC; // next step should not occur within less than MAX31865_MIN_SAMPLING_TIME_MSEC from the last one
+      } break;
+    }
+
+  #endif
 
-  return rtd;
+  return lastRead;
 }
 
 /**
  * Calculate and return the resistance value of the connected RTD.
  *
- * @param  refResistor The value of the matching reference resistor, usually 430 or 4300
  * @return             The raw RTD resistance value, NOT temperature!
  */
 float MAX31865::readResistance() {
   // Strip the error bit (D0) and convert to a float ratio.
   // less precise method: (readRaw() * refRes) >> 16
-  return (((readRaw() >> 1) / 32768.0f) * refRes);
+  return ((readRaw() * RECIPROCAL(65536.0f)) * refRes - wireRes);
 }
 
 /**
@@ -301,7 +371,7 @@ float MAX31865::temperature() {
  * @return  Temperature in C
  */
 float MAX31865::temperature(uint16_t adc_val) {
-  return temperature(((adc_val) / 32768.0f) * refRes);
+  return temperature(((adc_val) * RECIPROCAL(32768.0f)) * refRes - wireRes);
 }
 
 /**
@@ -352,11 +422,8 @@ float MAX31865::temperature(float rtd_res) {
  * @param enable  whether to enable or disable the value
  */
 void MAX31865::setConfig(uint8_t config, bool enable) {
-  uint8_t t = readRegister8(MAX31865_CONFIG_REG);
-  if (enable)
-    t |= config;
-  else
-    t &= ~config; // disable
+  uint8_t t = stdFlags;
+  if (enable) t |= config; else t &= ~config;
   writeRegister8(MAX31865_CONFIG_REG, t);
 }
 
@@ -369,7 +436,6 @@ void MAX31865::setConfig(uint8_t config, bool enable) {
 uint8_t MAX31865::readRegister8(uint8_t addr) {
   uint8_t ret = 0;
   readRegisterN(addr, &ret, 1);
-
   return ret;
 }
 
@@ -380,14 +446,9 @@ uint8_t MAX31865::readRegister8(uint8_t addr) {
  * @return       both register contents as a single 16-bit int
  */
 uint16_t MAX31865::readRegister16(uint8_t addr) {
-  uint8_t buffer[2] = {0, 0};
+  uint8_t buffer[2] = { 0 };
   readRegisterN(addr, buffer, 2);
-
-  uint16_t ret = buffer[0];
-  ret <<= 8;
-  ret |= buffer[1];
-
-  return ret;
+  return uint16_t(buffer[0]) << 8 | buffer[1];
 }
 
 /**
@@ -399,12 +460,12 @@ uint16_t MAX31865::readRegister16(uint8_t addr) {
  */
 void MAX31865::readRegisterN(uint8_t addr, uint8_t buffer[], uint8_t n) {
   addr &= 0x7F; // make sure top bit is not set
-  if (sclkPin == TERN(LARGE_PINMAP, -1UL, -1))
+  if (sclkPin == TERN(LARGE_PINMAP, -1UL, 255))
     SPI.beginTransaction(spiConfig);
   else
-    WRITE(sclkPin, LOW);
+    digitalWrite(sclkPin, LOW);
 
-  WRITE(cselPin, LOW);
+  digitalWrite(cselPin, LOW);
 
   #ifdef TARGET_LPC1768
     DELAY_CYCLES(spiSpeed);
@@ -414,16 +475,13 @@ void MAX31865::readRegisterN(uint8_t addr, uint8_t buffer[], uint8_t n) {
 
   while (n--) {
     buffer[0] = spiTransfer(0xFF);
-    #ifdef MAX31865_DEBUG_SPI
-      SERIAL_ECHOLNPGM("buffer read ", n, " data: ", buffer[0]);
-    #endif
     buffer++;
   }
 
-  if (sclkPin == TERN(LARGE_PINMAP, -1UL, -1))
+  if (sclkPin == TERN(LARGE_PINMAP, -1UL, 255))
     SPI.endTransaction();
 
-  WRITE(cselPin, HIGH);
+  digitalWrite(cselPin, HIGH);
 }
 
 /**
@@ -433,12 +491,12 @@ void MAX31865::readRegisterN(uint8_t addr, uint8_t buffer[], uint8_t n) {
  * @param data  the data to write
  */
 void MAX31865::writeRegister8(uint8_t addr, uint8_t data) {
-  if (sclkPin == TERN(LARGE_PINMAP, -1UL, -1))
+  if (sclkPin == TERN(LARGE_PINMAP, -1UL, 255))
     SPI.beginTransaction(spiConfig);
   else
-    WRITE(sclkPin, LOW);
+    digitalWrite(sclkPin, LOW);
 
-  WRITE(cselPin, LOW);
+  digitalWrite(cselPin, LOW);
 
   #ifdef TARGET_LPC1768
     DELAY_CYCLES(spiSpeed);
@@ -447,10 +505,10 @@ void MAX31865::writeRegister8(uint8_t addr, uint8_t data) {
   spiTransfer(addr | 0x80); // make sure top bit is set
   spiTransfer(data);
 
-  if (sclkPin == TERN(LARGE_PINMAP, -1UL, -1))
+  if (sclkPin == TERN(LARGE_PINMAP, -1UL, 255))
     SPI.endTransaction();
 
-  WRITE(cselPin, HIGH);
+  digitalWrite(cselPin, HIGH);
 }
 
 /**
@@ -463,36 +521,41 @@ void MAX31865::writeRegister8(uint8_t addr, uint8_t data) {
  * @return    the 8-bit response
  */
 uint8_t MAX31865::spiTransfer(uint8_t x) {
-  if (sclkPin == TERN(LARGE_PINMAP, -1UL, -1))
+
+  if (sclkPin == TERN(LARGE_PINMAP, -1UL, 255))
     return SPI.transfer(x);
 
   #ifdef TARGET_LPC1768
+
     return swSpiTransfer(x, spiSpeed, sclkPin, misoPin, mosiPin);
+
   #else
+
     uint8_t reply = 0;
     for (int i = 7; i >= 0; i--) {
-      WRITE(sclkPin, HIGH);         DELAY_NS_VAR(spiDelay);
+      digitalWrite(sclkPin, HIGH);       DELAY_NS_VAR(spiDelay);
       reply <<= 1;
-      WRITE(mosiPin, x & _BV(i));   DELAY_NS_VAR(spiDelay);
-      if (READ(misoPin)) reply |= 1;
-      WRITE(sclkPin, LOW);          DELAY_NS_VAR(spiDelay);
+      digitalWrite(mosiPin, x & _BV(i)); DELAY_NS_VAR(spiDelay);
+      if (digitalRead(misoPin)) reply |= 1;
+      digitalWrite(sclkPin, LOW);        DELAY_NS_VAR(spiDelay);
     }
     return reply;
+
   #endif
 }
 
 void MAX31865::softSpiBegin(const uint8_t spi_speed) {
-  #ifdef MAX31865_DEBUG
-    SERIAL_ECHOLNPGM("Initializing MAX31865 Software SPI");
-  #endif
+  DEBUG_ECHOLNPGM("Initializing MAX31865 Software SPI");
+
   #ifdef TARGET_LPC1768
     swSpiBegin(sclkPin, misoPin, mosiPin);
     spiSpeed = swSpiInit(spi_speed, sclkPin, mosiPin);
   #else
     spiDelay = (100UL << spi_speed) / 3; // Calculate delay in ns. Top speed is ~10MHz, or 100ns delay between bits.
-    OUT_WRITE(sclkPin, LOW);
-    SET_OUTPUT(mosiPin);
-    SET_INPUT(misoPin);
+    pinMode(sclkPin, OUTPUT);
+    digitalWrite(sclkPin, LOW);
+    pinMode(mosiPin, OUTPUT);
+    pinMode(misoPin, INPUT);
   #endif
 }
 

Marlin/src/libs/MAX31865.h

@@ -41,6 +41,8 @@
  */
 #pragma once
 
+//#define DEBUG_MAX31865
+
 #include "../inc/MarlinConfig.h"
 #include "../HAL/shared/Delay.h"
 #include HAL_PATH(../HAL, MarlinSPI.h)
@@ -84,6 +86,14 @@ typedef enum max31865_numwires {
   MAX31865_4WIRE = 0
 } max31865_numwires_t;
 
+#if DISABLED(MAX31865_USE_AUTO_MODE)
+  typedef enum one_shot_event : uint8_t {
+    SETUP_BIAS_VOLTAGE,
+    SETUP_1_SHOT_MODE,
+    READ_RTD_REG
+  } one_shot_event_t;
+#endif
+
 /* Interface class for the MAX31865 RTD Sensor reader */
 class MAX31865 {
 private:
@@ -97,7 +107,21 @@ private:
     uint16_t spiDelay;
   #endif
 
-  float zeroRes, refRes;
+  float zeroRes, refRes, wireRes;
+
+  #if ENABLED(MAX31865_USE_READ_ERROR_DETECTION)
+    millis_t lastReadStamp = 0;
+  #endif
+
+  uint16_t lastRead = 0;
+  uint8_t lastFault = 0;
+
+  #if DISABLED(MAX31865_USE_AUTO_MODE)
+    millis_t nextEventStamp;
+    one_shot_event_t nextEvent;
+  #endif
+
+  uint8_t stdFlags = 0;
 
   void setConfig(uint8_t config, bool enable);
 
@@ -110,8 +134,15 @@ private:
 
   void softSpiBegin(const uint8_t spi_speed);
 
+  void initFixedFlags(max31865_numwires_t wires);
+
+  void enable50HzFilter(bool b);
+  void enableBias();
+  void oneShot();
+  void resetFlags();
+
 public:
-  #ifdef LARGE_PINMAP
+  #if ENABLED(LARGE_PINMAP)
     MAX31865(uint32_t spi_cs, uint8_t pin_mapping);
     MAX31865(uint32_t spi_cs, uint32_t spi_mosi, uint32_t spi_miso,
              uint32_t spi_clk, uint8_t pin_mapping);
@@ -121,17 +152,11 @@ public:
              int8_t spi_clk);
   #endif
 
-  void begin(max31865_numwires_t wires, float zero, float ref);
+  void begin(max31865_numwires_t wires, float zero_res, float ref_res, float wire_res);
 
   uint8_t readFault();
   void clearFault();
 
-  void setWires(max31865_numwires_t wires);
-  void autoConvert(bool b);
-  void enable50HzFilter(bool b);
-  void enableBias(bool b);
-  void oneShot();
-
   uint16_t readRaw();
   float readResistance();
   float temperature();

Marlin/src/module/temperature.cpp

@@ -2202,11 +2202,8 @@ void Temperature::init() {
     #elif TEMP_SENSOR_IS_MAX(0, 31865)
       max31865_0.begin(
         MAX31865_WIRES(MAX31865_SENSOR_WIRES_0) // MAX31865_2WIRE, MAX31865_3WIRE, MAX31865_4WIRE
-        OPTARG(LIB_INTERNAL_MAX31865, MAX31865_SENSOR_OHMS_0, MAX31865_CALIBRATION_OHMS_0)
+        OPTARG(LIB_INTERNAL_MAX31865, MAX31865_SENSOR_OHMS_0, MAX31865_CALIBRATION_OHMS_0, MAX31865_WIRE_OHMS_0)
       );
-      #if defined(LIB_INTERNAL_MAX31865) && ENABLED(MAX31865_50HZ_FILTER)
-        max31865_0.enable50HzFilter(1);
-      #endif
     #endif
 
     #if TEMP_SENSOR_IS_MAX(1, 6675) && HAS_MAX6675_LIBRARY
@@ -2216,11 +2213,8 @@ void Temperature::init() {
     #elif TEMP_SENSOR_IS_MAX(1, 31865)
       max31865_1.begin(
         MAX31865_WIRES(MAX31865_SENSOR_WIRES_1) // MAX31865_2WIRE, MAX31865_3WIRE, MAX31865_4WIRE
-        OPTARG(LIB_INTERNAL_MAX31865, MAX31865_SENSOR_OHMS_1, MAX31865_CALIBRATION_OHMS_1)
+        OPTARG(LIB_INTERNAL_MAX31865, MAX31865_SENSOR_OHMS_1, MAX31865_CALIBRATION_OHMS_1, MAX31865_WIRE_OHMS_1)
       );
-      #if defined(LIB_INTERNAL_MAX31865) && ENABLED(MAX31865_50HZ_FILTER)
-        max31865_1.enable50HzFilter(1);
-      #endif
     #endif
     #undef MAX31865_WIRES
     #undef _MAX31865_WIRES