diff --git a/README.md b/README.md
index 8b8e477..b52e61f 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 20211029, see the [changelog](changelog.md) for details.  
+Latest build date is 20211109, 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.
 
 ---
diff --git a/changelog.md b/changelog.md
index 37afbe4..08aa0dc 100644
--- a/changelog.md
+++ b/changelog.md
@@ -1,6 +1,26 @@
 ## grblHAL changelog
 
-Build 2021029:
+Build 20211108:
+
+Core:
+* Renamed default hostnames/device names from _Grbl_ to _grblHAL_.
+* Added early application of constraints for feedrate and spindle RPM overrides to avoid variable under/overflow. From PR#83.
+* Added higher level \(than generic GPIO\) interrupt handler registration to HAL.
+* Added optional MCU peripheral \(other than GPIO\) pin registration to HAL. For `$pins` report.
+* Added region for [third party plugin](https://github.com/grblHAL/plugins#i-have-written-a-plugin-and-i-want-to-make-it-available-to-grblhal-users) init functions to _plugins_init.h_.
+
+Plugins:
+* Modified keypad plugin to claim strobe interrupt only when using I2C, added `KEYPAD_ENABLE 2` option to _my_machine.h_ to not claim it.
+* Fixed botched include in Bluetooth plugin, added pin description to claimed UART pins.
+* Made Modbus plugin configuration symbols settable from compiler command line, added pin description to claimed UART pins.
+
+Drivers:
+* Updated most to provide peripheral pin info to `$pins` report.
+* Some bug fixes.
+
+---
+
+Build 20211029:
 
 Core:
 * Fixed variable name typo.
@@ -13,7 +33,9 @@ Drivers:
 * Updated for HAL function pointer rename, multiple Modbus clients where relevant.
 * Added support for using UART8 as serial port in iMXRT1062 driver.
 
-Build 2021024:
+---
+
+Build 20211024:
 
 Core:
 * Moved @ G59.3 probing event call earlier in code, added check for X and Y homed.
@@ -28,7 +50,7 @@ Drivers:
 
 ---
 
-Build 2021019:
+Build 20211019:
 
 Core:
 * Some minor changes to better support Trinamic drivers, probing and drivers/boards with limited number of control inputs \(cycle start, feed hold, ...\).
@@ -46,7 +68,7 @@ Templates:
 
 ---
 
-Build 2021015:
+Build 20211015:
 
 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.
@@ -61,7 +83,7 @@ Templates:
 
 ---
 
-Build 2021010:
+Build 20211010:
 
 Core:
 * Added enum and associated get function for system defined named parameters.
diff --git a/crossbar.h b/crossbar.h
index d995cc6..7ce2ed1 100644
--- a/crossbar.h
+++ b/crossbar.h
@@ -52,7 +52,8 @@ typedef enum {
     Input_LimitV_Max,
     Input_MISO,
     Input_RX,
-    Input_KeypadStrobe,
+    Input_KeypadStrobe, // To be deprecated?
+    Input_I2CStrobe,
     Input_QEI_A,
     Input_QEI_B,
     Input_QEI_Select,
@@ -171,6 +172,7 @@ PROGMEM static const pin_name_t pin_names[] = {
    { .function = Input_MISO,             .name = "MISO" },
    { .function = Input_RX,               .name = "RX" },
    { .function = Input_KeypadStrobe,     .name = "Keypad strobe" },
+   { .function = Input_I2CStrobe,        .name = "I2C strobe" },
    { .function = Input_QEI_A,            .name = "QEI A" },
    { .function = Input_QEI_B,            .name = "QEI B" },
    { .function = Input_QEI_Select,       .name = "QEI select" },
@@ -284,6 +286,18 @@ typedef enum {
     IRQ_Mode_All     = 0b11111  //!< 0b11111 (0x1F) - only used to report port capability.
 } pin_irq_mode_t;
 
+typedef enum {
+    IRQ_I2C_Strobe = 0
+} irq_type_t;
+
+typedef bool (*irq_callback_ptr)(uint_fast8_t id, bool level);
+
+typedef struct driver_irq_handler {
+    irq_type_t type;
+    irq_callback_ptr callback;
+    struct driver_irq_handler *next;
+} driver_irq_handler_t;
+
 typedef enum {
     PullMode_None    = 0b00,
     PullMode_Up      = 0b01,
@@ -335,4 +349,18 @@ typedef struct {
     xbar_event_ptr on_event;
 } xbar_t;
 
+typedef struct {
+    pin_function_t function;
+    pin_group_t group;
+    void *port;
+    uint_fast8_t pin;
+    pin_mode_t mode;
+    const char *description;
+} periph_pin_t;
+
+typedef struct periph_signal {
+    periph_pin_t pin;
+    struct periph_signal *next;
+} periph_signal_t;
+
 #endif
diff --git a/driver_opts.h b/driver_opts.h
index e577d67..ce3e1b7 100644
--- a/driver_opts.h
+++ b/driver_opts.h
@@ -84,6 +84,15 @@
 #ifndef KEYPAD_ENABLE
 #define KEYPAD_ENABLE       0
 #endif
+#if KEYPAD_ENABLE == 1
+#ifdef I2C_STROBE_ENABLE
+#undef I2C_STROBE_ENABLE
+#endif
+#define I2C_STROBE_ENABLE   1
+#endif
+#ifndef I2C_STROBE_ENABLE
+#define I2C_STROBE_ENABLE   0
+#endif
 #ifndef EEPROM_ENABLE
 #define EEPROM_ENABLE       0
 #endif
@@ -132,9 +141,6 @@
 #ifndef ODOMETER_ENABLE
 #define ODOMETER_ENABLE     0
 #endif
-#ifndef BLUETOOTH_ENABLE
-#define BLUETOOTH_ENABLE    0
-#endif
 #ifndef OPENPNP_ENABLE
 #define OPENPNP_ENABLE      0
 #endif
@@ -145,6 +151,19 @@
 #define LIMITS_OVERRIDE_ENABLE  0
 #endif
 
+#ifndef BLUETOOTH_ENABLE
+#define BLUETOOTH_ENABLE    0
+#endif
+#if BLUETOOTH_ENABLE
+#ifndef BLUETOOTH_DEVICE
+#define BLUETOOTH_DEVICE    "grblHAL"
+#endif
+#ifndef BLUETOOTH_SERVICE
+#define BLUETOOTH_SERVICE   "grblHAL Serial Port" // Minimum 8 characters, or blank for open
+#endif
+#endif
+
+
 #ifdef ENABLE_SAFETY_DOOR_INPUT_PIN
 #define SAFETY_DOOR_ENABLE 1
 #else
@@ -218,7 +237,7 @@
 
 #if ETHERNET_ENABLE
 #ifndef NETWORK_HOSTNAME
-#define NETWORK_HOSTNAME        "GRBL"
+#define NETWORK_HOSTNAME        "grblHAL"
 #endif
 #ifndef NETWORK_IPMODE
 #define NETWORK_IPMODE          1 // 0 = static, 1 = DHCP, 2 = AutoIP
diff --git a/errors.h b/errors.h
index c7d6ef5..a00d944 100644
--- a/errors.h
+++ b/errors.h
@@ -108,7 +108,7 @@ typedef enum {
 
 typedef struct {
     status_code_t id;
-    const char *name;
+    const char *xname;
     const char *description;
 } status_detail_t;
 
diff --git a/grbl.h b/grbl.h
index ab42228..27b9798 100644
--- a/grbl.h
+++ b/grbl.h
@@ -34,7 +34,7 @@
 #else
 #define GRBL_VERSION "1.1f"
 #endif
-#define GRBL_VERSION_BUILD "20211029"
+#define GRBL_VERSION_BUILD "20211107"
 
 // The following symbols are set here if not already set by the compiler or in config.h
 // Do NOT change here!
diff --git a/grbllib.c b/grbllib.c
index c907542..82cb1d2 100644
--- a/grbllib.c
+++ b/grbllib.c
@@ -85,6 +85,11 @@ void dummy_bool_handler (bool arg)
     // NOOP
 }
 
+static bool dummy_irq_claim (irq_type_t irq, uint_fast8_t id, irq_callback_ptr callback)
+{
+    return false;
+}
+
 // main entry point
 
 int grbl_enter (void)
@@ -108,6 +113,7 @@ int grbl_enter (void)
     hal.driver_reset = dummy_handler;
     hal.irq_enable = dummy_handler;
     hal.irq_disable = dummy_handler;
+    hal.irq_claim = dummy_irq_claim;
     hal.nvs.size = GRBL_NVS_SIZE;
     hal.limits.interrupt_callback = limit_interrupt_handler;
     hal.control.interrupt_callback = control_interrupt_handler;
diff --git a/hal.h b/hal.h
index f429d32..215082b 100644
--- a/hal.h
+++ b/hal.h
@@ -170,6 +170,23 @@ typedef struct {
     ioport_register_interrupt_handler_ptr register_interrupt_handler;
 } io_port_t;
 
+/*! \brief Pointer to function for registering information about a peripheral pin.
+\param pin as periph_pin_t struct containing pin information.
+*/
+typedef void (*register_periph_pin_ptr)(const periph_pin_t *pin);
+
+/*! \brief Pointer to function for setting pin description for a peripheral pin.
+\param function as #pin_function_t enum.
+\param group as #pin_group_t enum.
+\param s pointer to null terminated description string.
+*/
+typedef void (*set_periph_pin_description_ptr)(const pin_function_t function, const pin_group_t group, const char *description);
+
+typedef struct {
+    register_periph_pin_ptr register_pin;               //!< Opional handler for registering information about a peripheral pin (with the driver).
+    set_periph_pin_description_ptr set_pin_description; //!< Optional handler for setting a description of a peripheral pin.
+} periph_port_t;
+
 /*! \brief Pointer to callback function for pin enumerations.
 \param pin pointer to the \a xbar_t structure holding the pin information.
 */
@@ -610,6 +627,13 @@ typedef struct {
     encoder_reset_ptr reset;                    //!< Optional handler for resetting data for an encoder.
 } encoder_ptrs_t;
 
+/*! \brief Pointer to function for claiming higher level interrupt requests (irq).
+\param irq irq type as a #irq_type_t enum value.
+\param id irq id, normally 0, > 0 if there are several sources for the same irq type.
+\param callback function as a \a irq_callback_ptr function pointer.
+*/
+typedef bool (*irq_claim_ptr)(irq_type_t irq, uint_fast8_t id, irq_callback_ptr callback);
+
 /*! \brief HAL structure used for the driver interface.
 
 This structure contains properties and function pointers (to handlers) that the core uses to communicate with the driver.
@@ -674,6 +698,9 @@ typedef struct {
     //! \brief Optional handler to enable global interrupts.
     void (*irq_disable)(void);
 
+    //! \brief Optional handler for claiming higher level interrupts. Set to a dummy handler on startup.
+    irq_claim_ptr irq_claim;
+
     limits_ptrs_t limits;                   //!< Handlers for limit switches.
     homing_ptrs_t homing;                   //!< Handlers for limit switches, used by homing cycle.
     control_signals_ptrs_t control;         //!< Handlers for control switches.
@@ -686,6 +713,7 @@ typedef struct {
     probe_ptrs_t probe;                     //!< Optional handlers for probe input(s).
     tool_ptrs_t tool;                       //!< Optional handlers for tool changes.
     io_port_t port;                         //!< Optional handlers for axuillary I/O (adds support for M62-M66).
+    periph_port_t periph_port;              //!< Optional handlers for peripheral pin registration.
     driver_reset_ptr driver_reset;          //!< Optional handler, called on soft resets. Set to a dummy handler by the core at startup.
     nvs_io_t nvs;                           //!< Optional handlers for storing/retrieving settings and data to/from non-volatile storage (NVS).
     enumerate_pins_ptr enumerate_pins;      //!< Optional handler for enumerating pins used by the driver.
diff --git a/nuts_bolts.h b/nuts_bolts.h
index 6411481..ef41c55 100644
--- a/nuts_bolts.h
+++ b/nuts_bolts.h
@@ -156,21 +156,24 @@ typedef enum {
 #define STRLEN_COORDVALUE (MAX_INT_DIGITS + N_DECIMAL_COORDVALUE_INCH + 1) // 8.4 format - excluding terminating null
 
 // Useful macros
-#define clear_vector(a) memset(a, 0, sizeof(a))
 #ifndef max
 #define max(a,b) (((a) > (b)) ? (a) : (b))
 #endif
 #ifndef min
 #define min(a,b) (((a) < (b)) ? (a) : (b))
 #endif
-#define isequal_position_vector(a,b) !memcmp(a, b, sizeof(coord_data_t))
+#ifndef constrain
+#define constrain(val, min, max) ((val) < (min) ? (min) : ((val) > (max) ? (max) : (val)))
+#endif
+#define clear_vector(a) memset(a, 0, sizeof(a))
+#define isequal_position_vector(a, b) !memcmp(a, b, sizeof(coord_data_t))
 
 // Bit field and masking macros
 #ifndef bit
 #define bit(n) (1UL << n)
 #endif
-#define bit_true(x,mask) (x) |= (mask)
-#define bit_false(x,mask) (x) &= ~(mask)
+#define bit_true(x, mask) (x) |= (mask)
+#define bit_false(x, mask) (x) &= ~(mask)
 #define BIT_SET(x, bit, v) { if (v) { x |= (bit); } else { x &= ~(bit); } }
 
 #define bit_istrue(x, mask) ((x & (mask)) != 0)
diff --git a/pin_bits_masks.h b/pin_bits_masks.h
index b5ecbba..8de4a16 100644
--- a/pin_bits_masks.h
+++ b/pin_bits_masks.h
@@ -94,8 +94,8 @@
 #define PROBE_BIT               (1<<PROBE_PIN)
 #endif
 
-#if defined(KEYPAD_STROBE_PIN) && !defined(KEYPAD_STROBE_BIT)
-#define KEYPAD_STROBE_BIT       (1<<KEYPAD_STROBE_PIN)
+#if defined(I2C_STROBE_PIN) && !defined(I2C_STROBE_BIT)
+#define I2C_STROBE_BIT          (1<<I2C_STROBE_PIN)
 #endif
 
 #ifndef AUXINPUT_MASK
diff --git a/planner.c b/planner.c
index b3bd33d..294842c 100644
--- a/planner.c
+++ b/planner.c
@@ -570,7 +570,7 @@ void plan_feed_override (uint_fast8_t feed_override, uint_fast8_t rapid_override
     if(sys.override.control.feed_rate_disable)
         return;
 
-    feed_override = max(min(feed_override, MAX_FEED_RATE_OVERRIDE), MIN_FEED_RATE_OVERRIDE);
+    feed_override = constrain(feed_override, MIN_FEED_RATE_OVERRIDE, MAX_FEED_RATE_OVERRIDE);
 
     if ((feed_override != sys.override.feed_rate) || (rapid_override != sys.override.rapid_rate)) {
       sys.override.feed_rate = (uint8_t)feed_override;
diff --git a/plugins_init.h b/plugins_init.h
index bca7c28..3716a8f 100644
--- a/plugins_init.h
+++ b/plugins_init.h
@@ -55,6 +55,23 @@
 
     my_plugin_init();
 
+// Third party plugin definitions.
+// The code for these has to be downloaded from the source and placed in the same folder as driver.c
+// Note: Third party plugins may have more than one implementation, there is no "owner" of plugins listed here.
+//       It is also guaranteed that there will be no implementation in the grblHAL repository of these.
+
+#if PROBE_RELAY_ENABLE
+    extern void probe_relay_init (void);
+    probe_relay_init();
+#endif
+
+#if STATUS_LIGHT_ENABLE
+    extern void status_light_init (void);
+    status_light_init();
+#endif
+
+// End third party plugin definitions.
+
 #if ODOMETER_ENABLE
     extern void odometer_init (void);
     odometer_init(); // NOTE: this *must* be last plugin to be initialized as it claims storage at the end of NVS.
diff --git a/protocol.c b/protocol.c
index 819ae10..8362b4c 100644
--- a/protocol.c
+++ b/protocol.c
@@ -514,7 +514,8 @@ bool protocol_exec_rt_system (void)
 
         if((rt_exec = get_feed_override())) {
 
-            uint_fast8_t new_f_override = sys.override.feed_rate, new_r_override = sys.override.rapid_rate;
+            int_fast16_t new_f_override = sys.override.feed_rate;
+            uint_fast8_t new_r_override = sys.override.rapid_rate;
 
             do {
 
@@ -551,17 +552,19 @@ bool protocol_exec_rt_system (void)
                     case CMD_OVERRIDE_RAPID_LOW:
                         new_r_override = RAPID_OVERRIDE_LOW;
                         break;
-                  }
+                }
+
+                new_f_override = constrain(new_f_override, MIN_FEED_RATE_OVERRIDE, MAX_FEED_RATE_OVERRIDE);
 
             } while((rt_exec = get_feed_override()));
 
-            plan_feed_override(new_f_override, new_r_override);
+            plan_feed_override((uint_fast8_t)new_f_override, new_r_override);
         }
 
         if((rt_exec = get_accessory_override())) {
 
             bool spindle_stop = false;
-            uint_fast8_t last_s_override = sys.override.spindle_rpm;
+            int_fast16_t last_s_override = sys.override.spindle_rpm;
             coolant_state_t coolant_state = gc_state.modal.coolant;
 
             do {
@@ -610,9 +613,11 @@ bool protocol_exec_rt_system (void)
                         break;
                 }
 
+                last_s_override = constrain(last_s_override, MIN_SPINDLE_RPM_OVERRIDE, MAX_SPINDLE_RPM_OVERRIDE);
+
             } while((rt_exec = get_accessory_override()));
 
-            spindle_set_override(last_s_override);
+            spindle_set_override((uint_fast8_t)last_s_override);
 
           // NOTE: Since coolant state always performs a planner sync whenever it changes, the current
           // run state can be determined by checking the parser state.
diff --git a/report.c b/report.c
index 32cb6b0..cf8f0d7 100644
--- a/report.c
+++ b/report.c
@@ -358,12 +358,12 @@ static bool report_group_settings (const setting_group_detail_t *groups, const u
 {
     bool found = false;
     uint_fast8_t idx;
-    char c, *s, group[25];
+    char c, *s, group[26];
 
     for(idx = 0; idx < n_groups; idx++) {
 
         s = group;
-        strncpy(group, groups[idx].name, sizeof(group));
+        strncpy(group, groups[idx].name, sizeof(group) - 1);
 
         // Uppercase group name
         while((c = *s))
@@ -1846,14 +1846,15 @@ status_code_t report_alarm_details (bool grbl_format)
 
             if(grbl_format) {
                 write_quoted(uitoa(list->alarms[idx].id), ",");
-                write_quoted(list->alarms[idx].name, ",");
+                write_quoted("N/A", ",");
+//                write_quoted(list->alarms[idx].name, ",");
                 write_quoted(list->alarms[idx].description ? list->alarms[idx].description : "", NULL);
                 hal.stream.write(ASCII_EOL);
             } else {
                 hal.stream.write("[ALARMCODE:");
                 hal.stream.write(uitoa(list->alarms[idx].id));
                 hal.stream.write(vbar);
-                hal.stream.write(list->alarms[idx].name);
+//                hal.stream.write(list->alarms[idx].name);
                 hal.stream.write(vbar);
                 if(list->alarms[idx].description)
                     hal.stream.write(list->alarms[idx].description);
@@ -1882,14 +1883,15 @@ status_code_t report_error_details (bool grbl_format)
 
             if(grbl_format) {
                 write_quoted(uitoa(list->errors[idx].id), ",");
-                write_quoted(list->errors[idx].name, ",");
+                write_quoted("N/A", ",");
+//                write_quoted(list->errors[idx].name, ",");
                 write_quoted(list->errors[idx].description ? list->errors[idx].description : "", NULL);
                 hal.stream.write(ASCII_EOL);
             } else {
                 hal.stream.write("[ERRORCODE:");
                 hal.stream.write(uitoa(list->errors[idx].id));
                 hal.stream.write(vbar);
-                hal.stream.write(list->errors[idx].name);
+//                hal.stream.write(list->errors[idx].name);
                 hal.stream.write(vbar);
                 if(list->errors[idx].description)
                     hal.stream.write(list->errors[idx].description);
diff --git a/spindle_control.c b/spindle_control.c
index e003167..02afa03 100644
--- a/spindle_control.c
+++ b/spindle_control.c
@@ -34,7 +34,7 @@ void spindle_set_override (uint_fast8_t speed_override)
     if(sys.override.control.spindle_rpm_disable)
         return;
 
-    speed_override = max(min(speed_override, MAX_SPINDLE_RPM_OVERRIDE), MIN_SPINDLE_RPM_OVERRIDE);
+    speed_override = constrain(speed_override, MIN_SPINDLE_RPM_OVERRIDE, MAX_SPINDLE_RPM_OVERRIDE);
 
     if ((uint8_t)speed_override != sys.override.spindle_rpm) {
         sys.override.spindle_rpm = (uint8_t)speed_override;
diff --git a/stream.h b/stream.h
index db334a8..42da06b 100644
--- a/stream.h
+++ b/stream.h
@@ -196,6 +196,7 @@ typedef bool (*disable_rx_stream_ptr)(bool disable);
 //! Properties and handlers for stream I/O
 typedef struct {
     stream_type_t type;                                     //!< Type of stream.
+    uint8_t instance;                                       //!< Instance of stream type, starts from 0.
     bool connected;                                         //!< Set to true by the driver if stream is connected. _Optional._ Under consideration.
     get_stream_buffer_count_ptr get_rx_buffer_free;         //!< Handler for getting number of free characters in the input buffer.
     stream_write_ptr write;                                 //!< Handler for writing string to current output stream only.