Add initial support for probes requiring Tare and Enable pins

Marlin/Configuration.h

@@ -996,6 +996,28 @@
 // Feedrate (mm/min) for the "accurate" probe of each point
 #define Z_PROBE_SPEED_SLOW (Z_PROBE_SPEED_FAST / 2)
 
+// For probes that require an explicit enable input such as feedback an arm is deployed or an opto switch reporting in-range
+//#define PROBE_NEEDS_ENABLE
+#if ENABLED(PROBE_NEEDS_ENABLE)
+  #define PROBE_NEEDS_ENABLE_STATE LOW
+#endif
+//#define PROBE_ENABLE_PIN PC6 // Override default probe enable pin
+
+// Probe requires Tare - Usefull for Strain guage or Piezo type probes which may see force from cabling or bowden tubes following moves
+//#define PROBE_NEEDS_TARE
+#if ENABLED(PROBE_NEEDS_TARE)
+  #define PROBE_TARE_TIME  200    // Time to hold tare pin
+  #define PROBE_TARE_DELAY 200    // Dwell following tare before continuing
+  #define PROBE_TARE_STATE HIGH   // State to write pin for tare
+  //#define PROBE_TARE_PIN PA5      // Override default Tare pin
+  #if ENABLED(PROBE_NEEDS_ENABLE)
+    // Assume probe enable will come on in a Z window rather than detecting probe deployment.
+    // Useful when TARE can be assured outside enable range to avoid potential crash situations.
+    // Prevents tare unless enable switch is off
+    //#define PROBE_ENABLE_WINDOW
+  #endif
+#endif
+
 /**
  * Multiple Probing
  *

Marlin/src/module/endstops.cpp

@@ -280,6 +280,14 @@ void Endstops::init() {
     #endif
   #endif
 
+  #if PIN_EXISTS(PROBE_ENABLE_PIN)
+    SET_INPUT(PROBE_ENABLE_PIN)
+  #endif
+
+  #if ENABLED(PROBE_NEEDS_TARE)
+    probe.tare_z_probe();
+  #endif
+
   TERN_(ENDSTOP_INTERRUPTS_FEATURE, setup_endstop_interrupts());
 
   // Enable endstops
@@ -582,7 +590,7 @@ void Endstops::update() {
     #endif
   #endif
 
-  #if HAS_Z_MIN && !Z_SPI_SENSORLESS
+  #if HAS_Z_MIN && !Z_SPI_SENSORLESS && DISABLED(PROBE_NEEDS_ENABLE)
     UPDATE_ENDSTOP_BIT(Z, MIN);
     #if ENABLED(Z_MULTI_ENDSTOPS)
       #if HAS_Z2_MIN
@@ -608,10 +616,19 @@ void Endstops::update() {
   #endif
 
   // When closing the gap check the enabled probe
-  #if HAS_CUSTOM_PROBE_PIN
+  #if HAS_CUSTOM_PROBE_PIN && DISABLED(PROBE_NEEDS_ENABLE)
     UPDATE_ENDSTOP_BIT(Z, MIN_PROBE);
   #endif
 
+  #if ENABLED(PROBE_NEEDS_ENABLE)
+    #if HAS_CUSTOM_PROBE_PIN
+      UPDATE_ENDSTOP_BIT(Z, MIN);
+      SET_BIT_TO(live_state, _ENDSTOP(Z, MIN), ((READ(_ENDSTOP_PIN(Z, MIN)) != _ENDSTOP_INVERTING(Z, MIN_PROBE) && (READ(PROBE_ENABLE_PIN) == PROBE_NEEDS_ENABLE_STATE))));
+    #else
+      SET_BIT_TO(live_state, _ENDSTOP(Z, MIN), ((READ(_ENDSTOP_PIN(Z, MIN)) != _ENDSTOP_INVERTING(Z, MIN) && (READ(PROBE_ENABLE_PIN) == PROBE_NEEDS_ENABLE_STATE))));
+    #endif
+  #endif
+
   #if HAS_Z_MAX && !Z_SPI_SENSORLESS
     // Check both Z dual endstops
     #if ENABLED(Z_MULTI_ENDSTOPS)

Marlin/src/module/motion.cpp

@@ -1603,6 +1603,10 @@ void homeaxis(const AxisEnum axis) {
     if (axis == Z_AXIS && bltouch.deploy()) return; // The initial DEPLOY
   #endif
 
+  #if ENABLED(PROBE_NEEDS_TARE)
+    if (probe.tare_z_probe()) return;
+  #endif
+
   #if DISABLED(DELTA) && defined(SENSORLESS_BACKOFF_MM)
     const xy_float_t backoff = SENSORLESS_BACKOFF_MM;
     if (((ENABLED(X_SENSORLESS) && axis == X_AXIS) || (ENABLED(Y_SENSORLESS) && axis == Y_AXIS)) && backoff[axis])

Marlin/src/module/probe.cpp

@@ -479,6 +479,26 @@ bool Probe::probe_down_to_z(const float z, const feedRate_t fr_mm_s) {
   return !probe_triggered;
 }
 
+#if ENABLED(PROBE_NEEDS_TARE)
+bool Probe::tare_z_probe() {
+  #if ENABLED(PROBE_ENABLE_WINDOW)
+    if ((READ(PROBE_ENABLE_PIN) == PROBE_NEEDS_ENABLE_STATE)) {
+      SERIAL_ECHOLN("Cannot tare probe, already Enabled");
+      return true;
+    }
+  #endif
+
+  SERIAL_ECHOLN("Taring the probe");
+  WRITE(PROBE_TARE_PIN, PROBE_TARE_STATE);
+  delay(PROBE_TARE_TIME);
+  WRITE(PROBE_TARE_PIN, !PROBE_TARE_STATE);
+  delay(PROBE_TARE_DELAY);
+
+  endstops.hit_on_purpose();
+  return false;
+}
+#endif
+
 /**
  * @brief Probe at the current XY (possibly more than once) to find the bed Z.
  *
@@ -492,6 +512,11 @@ float Probe::run_z_probe(const bool sanity_check/*=true*/) {
 
   auto try_to_probe = [&](PGM_P const plbl, const float &z_probe_low_point, const feedRate_t fr_mm_s, const bool scheck, const float clearance) {
     // Do a first probe at the fast speed
+
+    #if ENABLED(PROBE_NEEDS_TARE)
+      if(tare_z_probe()) return true;
+    #endif
+
     const bool probe_fail = probe_down_to_z(z_probe_low_point, fr_mm_s),            // No probe trigger?
                early_fail = (scheck && current_position.z > -offset.z + clearance); // Probe triggered too high?
     #if ENABLED(DEBUG_LEVELING_FEATURE)
@@ -505,7 +530,7 @@ float Probe::run_z_probe(const bool sanity_check/*=true*/) {
     #else
       UNUSED(plbl);
     #endif
-    return probe_fail || early_fail;
+    return (int)(probe_fail || early_fail);
   };
 
   // Stop the probe before it goes too low to prevent damage.
@@ -516,6 +541,10 @@ float Probe::run_z_probe(const bool sanity_check/*=true*/) {
   #if TOTAL_PROBING == 2
 
     // Do a first probe at the fast speed
+    #if ENABLED(PROBE_NEEDS_TARE)
+      if(tare_z_probe()) return true;
+    #endif
+
     if (try_to_probe(PSTR("FAST"), z_probe_low_point, MMM_TO_MMS(Z_PROBE_SPEED_FAST),
                      sanity_check, Z_CLEARANCE_BETWEEN_PROBES) ) return NAN;
 
@@ -554,6 +583,9 @@ float Probe::run_z_probe(const bool sanity_check/*=true*/) {
   #endif
     {
       // Probe downward slowly to find the bed
+      #if ENABLED(PROBE_NEEDS_TARE)
+        if(tare_z_probe()) return true;
+      #endif
       if (try_to_probe(PSTR("SLOW"), z_probe_low_point, MMM_TO_MMS(Z_PROBE_SPEED_SLOW),
                        sanity_check, Z_CLEARANCE_MULTI_PROBE) ) return NAN;
 

Marlin/src/module/probe.h

@@ -206,6 +206,10 @@ public:
     static void set_probing_paused(const bool p);
   #endif
 
+  #if ENABLED(PROBE_NEEDS_TARE)
+    static bool tare_z_probe();
+  #endif
+
 private:
   static bool probe_down_to_z(const float z, const feedRate_t fr_mm_s);
   static void do_z_raise(const float z_raise);