diff --git a/README.md b/README.md
index ae11572..8720167 100644
--- a/README.md
+++ b/README.md
@@ -11,7 +11,7 @@ It has been written to complement grblHAL and has features such as proper keyboa
 
 ---
 
-Latest build date is 20211010, see the [changelog](changelog.md) for details.  
+Latest build date is 20211015, see the [changelog](changelog.md) for details.  
 __NOTE:__ Drivers built with more than three axes configured \(`N_AXIS` > `3`\) will force a settings reset when upgraded. Backup and restore of settings is recommended for these.
 
 ---
@@ -80,4 +80,4 @@ List of Supported G-Codes:
 Some [plugins](https://github.com/grblHAL/plugins) implements additional M-codes.
 
 ---
-2021-10-10
+2021-10-15
diff --git a/changelog.md b/changelog.md
index 6c3e671..976123f 100644
--- a/changelog.md
+++ b/changelog.md
@@ -1,10 +1,28 @@
 ## grblHAL changelog
 
+Build 2021015:
+
+Core:
+
+* Improved `grbl.on_probe_fixture` event signature by adding pointer to the pending tool when fired when M6 is executing \(NULL if not\) and a flag indicating that the current XY-position is within 5mm of G59.3.
+* A few minor fixes.
+
+Plugins:
+
+* I2C keypad: Switch to metric mode when jogging.
+* WebUI: added option to store read-only webui files in flash.
+
+Templates:
+
+* Updated the [probe select](https://github.com/grblHAL/Templates/blob/master/my_plugin/probe%20select/my_plugin.c) example for the `grbl.on_probe_fixture` signature change and added an optional mode select parameter to M401.
+
+---
+
 Build 2021010:
 
 Core:
 * Added enum and associated get function for system defined named parameters.
-* Added events (function pointers) for tool change mode 2 and 3 events (can be used to switch between probes) and for publishing active homing feedrate.
+* Added events (function pointers) for tool change mode 2 and 3 events \(can be used to switch between probes\) and for publishing active homing feedrate.
 
 Drivers:
 * Improved stream support in many drivers by adding support for _write_n_ characters. This is mainly used for outputting human readable settings descriptions.
diff --git a/config.h b/config.h
index 4f937d2..3f58888 100644
--- a/config.h
+++ b/config.h
@@ -361,6 +361,14 @@ __NOTE:__ these definitions are only referenced in this file. Do __NOT__ change!
 //#define DEFAULT_TOOLCHANGE_SEEK_RATE 200.0f     // mm/min
 //#define DEFAULT_TOOLCHANGE_PULLOFF_RATE 200.0f  // mm/min
 
+// The grbl.on_probe_fixture event handler is called by the default tool change algorithm when probing at G59.3.
+// In addition it will be called on a "normal" probe sequence if the XY position is
+// within the radius of the G59.3 position defined below.
+// Uncomment and change if the default value of 5mm is not suitable or set it to 0.0f to disable.
+// NOTE: A grbl.on_probe_fixture event handler is not installed by the core, it has to be provided
+//       by a driver or a plugin.
+//#define TOOLSETTER_RADIUS 5.0f
+
 // By default, Grbl sets all input pins to normal-low operation with their internal pull-up resistors
 // enabled. This simplifies the wiring for users by requiring only a normally closed (NC) switch connected
 // to ground. It is not recommended to use normally-open (NO) switches as this increases the risk
@@ -642,6 +650,10 @@ __NOTE:__ these definitions are only referenced in this file. Do __NOT__ change!
 #endif // DEFAULT_HOMING_ENABLE
 
 // Uncomment to enable experimental support for parameters and expressions
-#define NGC_EXPRESSIONS_ENABLE 1
+//#define NGC_EXPRESSIONS_ENABLE 1
+
+#ifndef TOOLSETTER_RADIUS
+#define TOOLSETTER_RADIUS 5.0f // Default value - do not change here!
+#endif
 
 #endif
diff --git a/core_handlers.h b/core_handlers.h
index da9844b..b68ffe0 100644
--- a/core_handlers.h
+++ b/core_handlers.h
@@ -80,7 +80,7 @@ typedef void (*on_unknown_feedback_message_ptr)(stream_write_ptr stream_write);
 typedef void (*on_stream_changed_ptr)(stream_type_t type);
 typedef bool (*on_laser_ppi_enable_ptr)(uint_fast16_t ppi, uint_fast16_t pulse_length);
 typedef void (*on_homing_rate_set_ptr)(axes_signals_t axes, float rate);
-typedef void (*on_probe_fixture_ptr)(bool on);
+typedef bool (*on_probe_fixture_ptr)(tool_data_t *tool, bool at_g59_3, bool on);
 typedef status_code_t (*on_unknown_sys_command_ptr)(sys_state_t state, char *line); // return Status_Unhandled.
 typedef status_code_t (*on_user_command_ptr)(char *line);
 typedef sys_commands_t *(*on_get_commands_ptr)(void);
diff --git a/grbl.h b/grbl.h
index aacac35..faa2997 100644
--- a/grbl.h
+++ b/grbl.h
@@ -34,7 +34,7 @@
 #else
 #define GRBL_VERSION "1.1f"
 #endif
-#define GRBL_VERSION_BUILD "20211010"
+#define GRBL_VERSION_BUILD "20211015"
 
 // The following symbols are set here if not already set by the compiler or in config.h
 // Do NOT change here!
diff --git a/motion_control.c b/motion_control.c
index 560c60f..a131df8 100644
--- a/motion_control.c
+++ b/motion_control.c
@@ -792,7 +792,7 @@ status_code_t mc_homing_cycle (axes_signals_t cycle)
         gc_state.modal.coolant.mask = 0;
         coolant_set_state(gc_state.modal.coolant);
 
-        // -------------------------------------------------------------------------------------
+        // ---------------------------------------------------------------------------
         // Perform homing routine. NOTE: Special motion case. Only system reset works.
 
         if (!home_all) // Perform homing cycle based on mask.
@@ -835,7 +835,7 @@ status_code_t mc_homing_cycle (axes_signals_t cycle)
         }
 
         // Homing cycle complete! Setup system for normal operation.
-        // -------------------------------------------------------------------------------------
+        // ---------------------------------------------------------
 
         // Sync gcode parser and planner positions to homed position.
         sync_position();
@@ -848,7 +848,6 @@ status_code_t mc_homing_cycle (axes_signals_t cycle)
             : Status_OK;
 }
 
-
 // Perform tool length probe cycle. Requires probe switch.
 // NOTE: Upon probe failure, the program will be stopped and placed into ALARM state.
 gc_probe_t mc_probe_cycle (float *target, plan_line_data_t *pl_data, gc_parser_flags_t parser_flags)
@@ -882,6 +881,13 @@ gc_probe_t mc_probe_cycle (float *target, plan_line_data_t *pl_data, gc_parser_f
     // Activate the probing state monitor in the stepper module.
     sys.probing_state = Probing_Active;
 
+#if COMPATIBILITY_LEVEL <= 1
+    bool at_g59_3 = false, probe_fixture = grbl.on_probe_fixture != NULL && state_get() != STATE_TOOL_CHANGE;
+
+    if(probe_fixture)
+        grbl.on_probe_fixture(NULL, at_g59_3 = system_xy_at_fixture(CoordinateSystem_G59_3, TOOLSETTER_RADIUS), true);
+#endif
+
     // Perform probing cycle. Wait here until probe is triggered or motion completes.
     system_set_exec_state_flag(EXEC_CYCLE_START);
     do {
@@ -904,6 +910,11 @@ gc_probe_t mc_probe_cycle (float *target, plan_line_data_t *pl_data, gc_parser_f
     hal.probe.configure(false, false);  // Re-initialize invert mask.
     protocol_execute_realtime();        // Check and execute run-time commands
 
+#if COMPATIBILITY_LEVEL <= 1
+    if(probe_fixture)
+        grbl.on_probe_fixture(NULL, at_g59_3, false);
+#endif
+
     // Reset the stepper and planner buffers to remove the remainder of the probe motion.
     st_reset();             // Reset step segment buffer.
     plan_reset();           // Reset planner buffer. Zero planner positions. Ensure probing motion is cleared.
diff --git a/ngc_expr.c b/ngc_expr.c
index 00e570a..8150a32 100644
--- a/ngc_expr.c
+++ b/ngc_expr.c
@@ -254,7 +254,7 @@ static status_code_t execute_unary (float *operand, ngc_unary_op_t operation)
             break;
 
         case NGCUnaryOp_FIX:
-            *operand = floor(*operand);
+            *operand = floorf(*operand);
             break;
 
         case NGCUnaryOp_FUP:
diff --git a/nuts_bolts.h b/nuts_bolts.h
index e03a9af..398224f 100644
--- a/nuts_bolts.h
+++ b/nuts_bolts.h
@@ -57,6 +57,11 @@
 #endif
 #endif
 
+#ifdef __MSP430F5529__
+#define isnanf(x) __isnanf(x)
+#define isinff(x) __isinff(x)
+#endif
+
 // Axis array index values. Must start with 0 and be continuous.
 #define X_AXIS 0 // Axis indexing value.
 #define Y_AXIS 1
diff --git a/system.c b/system.c
index d5a8199..d7ddb0f 100644
--- a/system.c
+++ b/system.c
@@ -83,6 +83,12 @@ static status_code_t set_startup_line1 (sys_state_t state, char *args);
 static status_code_t output_memmap (sys_state_t state, char *args);
 #endif
 
+// Simple hypotenuse computation function.
+inline static float hypot_f (float x, float y)
+{
+    return sqrtf(x*x + y*y);
+}
+
 // Pin change interrupt for pin-out commands, i.e. cycle start, feed hold, and reset. Sets
 // only the realtime command execute variable to have the main program execute these when
 // its ready. This works exactly like the character-based realtime commands when picked off
@@ -898,6 +904,23 @@ void system_convert_array_steps_to_mpos (float *position, int32_t *steps)
 #endif
 }
 
+// Checks if XY position is within coordinate system XY with given tolerance.
+// If tolerance is 0 false is returned.
+bool system_xy_at_fixture (coord_system_id_t id, float tolerance)
+{
+    bool ok = false;
+
+    coord_data_t target, position;
+
+    if(tolerance > 0.0f && settings_read_coord_data(id, &target.values)) {
+        system_convert_array_steps_to_mpos(position.values, sys.position);
+        ok = hypot_f(position.x - target.x, position.y - target.y) <= tolerance;
+    }
+
+    return ok;
+}
+
+
 // Checks and reports if target array exceeds machine travel limits. Returns false if check failed.
 // NOTE: max_travel is stored as negative
 // TODO: only check homed axes?
diff --git a/system.h b/system.h
index 8e46415..8d7b02d 100644
--- a/system.h
+++ b/system.h
@@ -287,6 +287,9 @@ void system_flag_wco_change (void);
 //! Updates a machine 'position' array based on the 'step' array sent.
 void system_convert_array_steps_to_mpos (float *position, int32_t *steps);
 
+//! Checks if XY position is within coordinate system XY with given tolerance.
+bool system_xy_at_fixture (coord_system_id_t id, float tolerance);
+
 //! Checks and reports if target array exceeds machine travel limits.
 bool system_check_travel_limits (float *target);
 
diff --git a/tool_change.c b/tool_change.c
index 42bda5b..fe7c016 100644
--- a/tool_change.c
+++ b/tool_change.c
@@ -79,7 +79,7 @@ static void change_completed (void)
     }
 
     if(probe_fixture)
-        grbl.on_probe_fixture(false);
+        grbl.on_probe_fixture(&current_tool, true, false);
 
     grbl.on_probe_completed = NULL;
     gc_state.tool_change = probe_fixture = false;
@@ -175,7 +175,7 @@ static void execute_probe (sys_state_t state)
     gc_parser_flags_t flags = {0};
 
     if(probe_fixture)
-        grbl.on_probe_fixture(true);
+        grbl.on_probe_fixture(next_tool, true, true);
 
     // G59.3 contains offsets to position of TLS.
     settings_read_coord_data(CoordinateSystem_G59_3, &offset.values);
@@ -328,7 +328,9 @@ static status_code_t tool_change (parser_state_t *parser_state)
 
     execute_posted = false;
     probe_fixture = grbl.on_probe_fixture != NULL &&
-                     (settings.tool_change.mode == ToolChange_Manual_G59_3 || settings.tool_change.mode == ToolChange_SemiAutomatic);
+                     (settings.tool_change.mode == ToolChange_Manual ||
+                       settings.tool_change.mode == ToolChange_Manual_G59_3 ||
+                        settings.tool_change.mode == ToolChange_SemiAutomatic);
     parser_state->tool_change = true;
 
     // Save current position.
@@ -443,7 +445,7 @@ status_code_t tc_probe_workpiece (void)
     plan_line_data_t plan_data = {0};
 
     if(probe_fixture)
-        grbl.on_probe_fixture(true);
+        grbl.on_probe_fixture(next_tool, system_xy_at_fixture(CoordinateSystem_G59_3, TOOLSETTER_RADIUS), true);
 
     // Get current position.
     system_convert_array_steps_to_mpos(target.values, sys.position);