diff --git a/README.md b/README.md
index 81ddca8..ee4da54 100644
--- a/README.md
+++ b/README.md
@@ -13,7 +13,7 @@ It has been written to complement grblHAL and has features such as proper keyboa
 
 ---
 
-Latest build date is 20231210, see the [changelog](changelog.md) for details.  
+Latest build date is 20231216, see the [changelog](changelog.md) for details.  
 __NOTE:__ A settings reset will be performed on an update of builds earlier than 20230125. Backup and restore of settings is recommended.  
 
 ---
diff --git a/changelog.md b/changelog.md
index e7bd105..479b80f 100644
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,20 @@
 ## grblHAL changelog
 
+<a name="20231216"/>Build 20231216
+
+Core:
+
+* Refactored canned cycles to better match how LinuxCNC actually implements them. Ref. [ioSender issue 348](https://github.com/terjeio/ioSender/issues/348).  
+__NOTE:__ The implementation may still be incorrect - use with care!
+
+Drivers:
+
+* SAM3X8E: added laser plugins.
+
+* LPC176x: added laser and spindle plugins.
+
+---
+
 <a name="20231210"/>Build 20231210
 
 Core:
diff --git a/crossbar.h b/crossbar.h
index 19b323c..271dfc6 100644
--- a/crossbar.h
+++ b/crossbar.h
@@ -70,6 +70,7 @@ typedef enum {
     Input_RX,
     Input_KeypadStrobe, // To be deprecated? Use Input_I2CStrobe instead.
     Input_I2CStrobe,
+    Input_SdCardDetect,
     Input_QEI_A,
     Input_QEI_B,
     Input_QEI_Select,
@@ -217,6 +218,7 @@ PROGMEM static const pin_name_t pin_names[] = {
     { .function = Input_RX,                  .name = "RX" },
     { .function = Input_KeypadStrobe,        .name = "Keypad strobe" },
     { .function = Input_I2CStrobe,           .name = "I2C strobe" },
+    { .function = Input_SdCardDetect,        .name = "SD card detect" },
     { .function = Input_QEI_A,               .name = "QEI A" },
     { .function = Input_QEI_B,               .name = "QEI B" },
     { .function = Input_QEI_Select,          .name = "QEI select" },
diff --git a/gcode.c b/gcode.c
index e727ee0..39405ac 100644
--- a/gcode.c
+++ b/gcode.c
@@ -2494,7 +2494,6 @@ status_code_t gc_execute_block (char *block)
                     gc_state.canned.xyz[plane.axis_1] = 0.0f;
                     gc_state.canned.rapid_retract = On;
                     gc_state.canned.spindle_off = Off;
-                    gc_state.canned.prev_position = gc_state.position[plane.axis_linear];
                 }
 
                 if(!gc_block.words.l)
diff --git a/gcode.h b/gcode.h
index 856a9e5..e399bd1 100644
--- a/gcode.h
+++ b/gcode.h
@@ -478,7 +478,6 @@ typedef struct {
     float xyz[3];
     float delta;
     float dwell;
-    float prev_position;
     float retract_position; //!< Canned cycle retract position
     bool rapid_retract;
     bool spindle_off;
diff --git a/grbl.h b/grbl.h
index 3c74805..ca7c987 100644
--- a/grbl.h
+++ b/grbl.h
@@ -42,7 +42,7 @@
 #else
 #define GRBL_VERSION "1.1f"
 #endif
-#define GRBL_BUILD 20231210
+#define GRBL_BUILD 20231216
 
 #define GRBL_URL "https://github.com/grblHAL"
 
diff --git a/motion_control.c b/motion_control.c
index 21fb0fd..7db630b 100644
--- a/motion_control.c
+++ b/motion_control.c
@@ -570,35 +570,35 @@ void mc_canned_drill (motion_mode_t motion, float *target, plan_line_data_t *pl_
             return;
     }
 
+    float position_linear = position[plane.axis_linear],
+          retract_to = canned->retract_mode == CCRetractMode_RPos ? canned->retract_position : position_linear;
+
     // rapid move to X, Y
     memcpy(position, target, sizeof(float) * N_AXIS);
-    position[plane.axis_linear] = canned->prev_position > canned->retract_position ? canned->prev_position : canned->retract_position;
+    position[plane.axis_linear] = position_linear;
     if(!mc_line(position, pl_data))
         return;
 
-    // if current Z > R, rapid move to R
-    if(position[plane.axis_linear] > canned->retract_position) {
-        position[plane.axis_linear] = canned->retract_position;
-        if(!mc_line(position, pl_data))
-            return;
-    }
-
-    if(canned->retract_mode == CCRetractMode_RPos)
-        canned->prev_position = canned->retract_position;
-
     while(repeats--) {
 
-        float current_z = canned->retract_position;
+        // if current Z > R, rapid move to R
+        if(position[plane.axis_linear] > canned->retract_position) {
+            position[plane.axis_linear] = canned->retract_position;
+            if(!mc_line(position, pl_data))
+                return;
+        }
 
-        while(current_z > canned->xyz[plane.axis_linear]) {
+        position_linear = position[plane.axis_linear];
 
-            current_z -= canned->delta;
-            if(current_z < canned->xyz[plane.axis_linear])
-                current_z = canned->xyz[plane.axis_linear];
+        while(position_linear > canned->xyz[plane.axis_linear]) {
+
+            position_linear -= canned->delta;
+            if(position_linear < canned->xyz[plane.axis_linear])
+                position_linear = canned->xyz[plane.axis_linear];
 
             pl_data->condition.rapid_motion = Off;
 
-            position[plane.axis_linear] = current_z;
+            position[plane.axis_linear] = position_linear;
             if(!mc_line(position, pl_data)) // drill
                 return;
 
@@ -613,12 +613,12 @@ void mc_canned_drill (motion_mode_t motion, float *target, plan_line_data_t *pl_
 
                 case MotionMode_DrillChipBreak:
                     position[plane.axis_linear] = position[plane.axis_linear] == canned->xyz[plane.axis_linear]
-                                                   ? canned->retract_position
+                                                   ? retract_to
                                                    : position[plane.axis_linear] + settings.g73_retract;
                     break;
 
                 default:
-                    position[plane.axis_linear] = canned->retract_position;
+                    position[plane.axis_linear] = retract_to;
                     break;
             }
 
@@ -630,6 +630,8 @@ void mc_canned_drill (motion_mode_t motion, float *target, plan_line_data_t *pl_
                 spindle_sync(pl_data->spindle.hal, gc_state.modal.spindle.state, pl_data->spindle.rpm);
         }
 
+        pl_data->condition.rapid_motion = On; // Set rapid motion condition flag.
+
        // rapid move to next position if incremental mode
         if(repeats && gc_state.modal.distance_incremental) {
             position[plane.axis_0] += canned->xyz[plane.axis_0];
@@ -640,13 +642,6 @@ void mc_canned_drill (motion_mode_t motion, float *target, plan_line_data_t *pl_
     }
 
     memcpy(target, position, sizeof(float) * N_AXIS);
-
-    if(canned->retract_mode == CCRetractMode_Previous && motion != MotionMode_DrillChipBreak && target[plane.axis_linear] < canned->prev_position) {
-        pl_data->condition.rapid_motion = On;
-        target[plane.axis_linear] = canned->prev_position;
-        if(!mc_line(target, pl_data))
-            return;
-    }
 }
 
 // Calculates depth-of-cut (DOC) for a given threading pass.
diff --git a/report.c b/report.c
index dcb6869..9267e81 100644
--- a/report.c
+++ b/report.c
@@ -699,7 +699,7 @@ void report_gcode_modes (void)
             hal.stream.write(gc_state.modal.tool_offset_mode == ToolLengthOffset_EnableDynamic ? ".1" : ".2");
     }
 
-    hal.stream.write(gc_state.canned.retract_mode == CCRetractMode_RPos ? " G99" : " G98");
+    hal.stream.write(gc_state.modal.retract_mode == CCRetractMode_RPos ? " G99" : " G98");
 
     if(gc_state.modal.scaling_active) {
         hal.stream.write(" G51:");