First arcs version. (Arcs not working ok)

Marlin/Configuration.h

@@ -1,245 +1,248 @@
-#ifndef CONFIGURATION_H
-#define CONFIGURATION_H
-
-//#define DEBUG_STEPS
-
-// BASIC SETTINGS: select your board type, thermistor type, axis scaling, and endstop configuration
-
-//// The following define selects which electronics board you have. Please choose the one that matches your setup
-// MEGA/RAMPS up to 1.2 = 3,
-// RAMPS 1.3 = 33
-// Gen6 = 5,
-// Sanguinololu 1.2 and above = 62
-// Ultimaker = 7,
-#define MOTHERBOARD 7
-//#define MOTHERBOARD 5
-
-
-//// Thermistor settings:
-// 1 is 100k thermistor
-// 2 is 200k thermistor
-// 3 is mendel-parts thermistor
-// 4 is 10k thermistor
-// 5 is ParCan supplied 104GT-2 100K
-// 6 is EPCOS 100k
-// 7 is 100k Honeywell thermistor 135-104LAG-J01
-#define THERMISTORHEATER_1 3
-#define THERMISTORHEATER_2 3
-#define THERMISTORBED 3
-
-//#define HEATER_0_USES_THERMISTOR
-//#define HEATER_1_USES_THERMISTOR
-#define HEATER_0_USES_AD595
-//#define HEATER_1_USES_AD595
-
-// Select one of these only to define how the bed temp is read.
-//#define BED_USES_THERMISTOR
-//#define BED_USES_AD595
-
-#define HEATER_CHECK_INTERVAL 50
-#define BED_CHECK_INTERVAL 5000
-
-
-//// Endstop Settings
-#define ENDSTOPPULLUPS // Comment this out (using // at the start of the line) to disable the endstop pullup resistors
-// The pullups are needed if you directly connect a mechanical endswitch between the signal and ground pins.
-const bool ENDSTOPS_INVERTING = true; // set to true to invert the logic of the endstops. 
-// For optos H21LOB set to true, for Mendel-Parts newer optos TCST2103 set to false
-
-// This determines the communication speed of the printer
-#define BAUDRATE 250000
-//#define BAUDRATE 115200
-//#define BAUDRATE 230400
-
-// Comment out (using // at the start of the line) to disable SD support:
-
-// #define ULTRA_LCD  //any lcd 
-
-#define ULTIPANEL
-#define ULTIPANEL
-#ifdef ULTIPANEL
- //#define NEWPANEL  //enable this if you have a click-encoder panel
- #define SDSUPPORT
- #define ULTRA_LCD
- #define LCD_WIDTH 20
-#define LCD_HEIGHT 4
-#else //no panel but just lcd 
-  #ifdef ULTRA_LCD
-    #define LCD_WIDTH 16
-    #define LCD_HEIGHT 2
-  #endif
-#endif
-
-
-//#define SDSUPPORT // Enable SD Card Support in Hardware Console
-
-
-
-const int dropsegments=5; //everything with this number of steps  will be ignored as move
-
-//// ADVANCED SETTINGS - to tweak parameters
-
-#include "thermistortables.h"
-
-// For Inverting Stepper Enable Pins (Active Low) use 0, Non Inverting (Active High) use 1
-#define X_ENABLE_ON 0
-#define Y_ENABLE_ON 0
-#define Z_ENABLE_ON 0
-#define E_ENABLE_ON 0
-
-// Disables axis when it's not being used.
-#define DISABLE_X false
-#define DISABLE_Y false
-#define DISABLE_Z false
-#define DISABLE_E false
-
-// Inverting axis direction
-#define INVERT_X_DIR true    // for Mendel set to false, for Orca set to true
-#define INVERT_Y_DIR false   // for Mendel set to true, for Orca set to false
-#define INVERT_Z_DIR true    // for Mendel set to false, for Orca set to true
-#define INVERT_E_DIR false   // for direct drive extruder v9 set to true, for geared extruder set to false
-
-//// ENDSTOP SETTINGS:
-// Sets direction of endstops when homing; 1=MAX, -1=MIN
-#define X_HOME_DIR -1
-#define Y_HOME_DIR -1
-#define Z_HOME_DIR -1
-
-#define min_software_endstops false //If true, axis won't move to coordinates less than zero.
-#define max_software_endstops false  //If true, axis won't move to coordinates greater than the defined lengths below.
-#define X_MAX_LENGTH 210
-#define Y_MAX_LENGTH 210
-#define Z_MAX_LENGTH 210
-
-//// MOVEMENT SETTINGS
-#define NUM_AXIS 4 // The axis order in all axis related arrays is X, Y, Z, E
-//note: on bernhards ultimaker 200 200 12 are working well.
-#define HOMING_FEEDRATE {50*60, 50*60, 12*60, 0}  // set the homing speeds
-//the followint checks if an extrusion is existent in the move. if _not_, the speed of the move is set to the maximum speed. 
-//!!!!!!Use only if you know that your printer works at the maximum declared speeds.
-// works around the skeinforge cool-bug. There all moves are slowed to have a minimum layer time. However slow travel moves= ooze
-#define TRAVELING_AT_MAXSPEED  
-#define AXIS_RELATIVE_MODES {false, false, false, false}
-
-#define MAX_STEP_FREQUENCY 40000 // Max step frequency for Ultimaker (5000 pps / half step)
-
-// default settings 
-
-#define DEFAULT_AXIS_STEPS_PER_UNIT   {79.87220447,79.87220447,200*8/3,14}                    // default steps per unit for ultimaker 
-#define DEFAULT_MAX_FEEDRATE          {160*60, 160*60, 10*60, 500000}        
-#define DEFAULT_MAX_ACCELERATION      {9000,9000,150,10000}    // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for skeinforge 40+, for older versions raise them a lot.
-
-#define DEFAULT_ACCELERATION          3000    // X, Y, Z and E max acceleration in mm/s^2 for printing moves 
-#define DEFAULT_RETRACT_ACCELERATION  7000   // X, Y, Z and E max acceleration in mm/s^2 for r retracts
-
-#define DEFAULT_MINIMUMFEEDRATE       10     // minimum feedrate
-#define DEFAULT_MINTRAVELFEEDRATE     10
-
-// minimum time in microseconds that a movement needs to take if the buffer is emptied.   Increase this number if you see blobs while printing high speed & high detail.  It will slowdown on the detailed stuff.
-#define DEFAULT_MINSEGMENTTIME        20000
-#define DEFAULT_XYJERK                30.0*60    
-#define DEFAULT_ZJERK                 10.0*60
-
-
-// The watchdog waits for the watchperiod in milliseconds whenever an M104 or M109 increases the target temperature
-//this enables the watchdog interrupt.
-#define USE_WATCHDOG
-//you cannot reboot on a mega2560 due to a bug in he bootloader. Hence, you have to reset manually, and this is done hereby:
-#define RESET_MANUAL
-
-#define WATCHDOG_TIMEOUT 4
-
-
-
-//// Experimental watchdog and minimal temp
-// The watchdog waits for the watchperiod in milliseconds whenever an M104 or M109 increases the target temperature
-// If the temperature has not increased at the end of that period, the target temperature is set to zero. It can be reset with another M104/M109
-//#define WATCHPERIOD 5000 //5 seconds
-
-// Actual temperature must be close to target for this long before M109 returns success
-//#define TEMP_RESIDENCY_TIME 20  // (seconds)
-//#define TEMP_HYSTERESIS 5       // (C°) range of +/- temperatures considered "close" to the target one
-
-//// The minimal temperature defines the temperature below which the heater will not be enabled
-#define HEATER_0_MINTEMP 5
-//#define HEATER_1_MINTEMP 5
-//#define BED_MINTEMP 5
-
-
-// When temperature exceeds max temp, your heater will be switched off.
-// This feature exists to protect your hotend from overheating accidentally, but *NOT* from thermistor short/failure!
-// You should use MINTEMP for thermistor short/failure protection.
-#define HEATER_0_MAXTEMP 275
-//#define_HEATER_1_MAXTEMP 275
-//#define BED_MAXTEMP 150
-
-
-
-
-
-
-
-#define PIDTEMP
-#ifdef PIDTEMP
-  /// PID settings:
-  // Uncomment the following line to enable PID support.
-  //#define SMOOTHING
-  //#define SMOOTHFACTOR 5.0
-  //float current_raw_average=0;
-    #define K1 0.95 //smoothing of the PID
-  //#define PID_DEBUG // Sends debug data to the serial port. 
-  //#define PID_OPENLOOP 1 // Puts PID in open loop. M104 sets the output power in %
-  #define PID_MAX 255 // limits current to nozzle
-  #define PID_INTEGRAL_DRIVE_MAX 255
-  #define PID_dT 0.1
- //machine with red silicon: 1950:45 second ; with fan fully blowin 3000:47
-
-  #define PID_CRITIAL_GAIN 3000
-  #define PID_SWING_AT_CRITIAL 45 //seconds
-  #define PIDIADD 5
-  /*
-  //PID according to Ziegler-Nichols method
-  float Kp = 0.6*PID_CRITIAL_GAIN; 
-  float Ki =PIDIADD+2*Kp/PID_SWING_AT_CRITIAL*PID_dT;  
-  float Kd = Kp*PID_SWING_AT_CRITIAL/8./PID_dT;  
-  */
-  //PI according to Ziegler-Nichols method
-  #define  DEFAULT_Kp (PID_CRITIAL_GAIN/2.2) 
-  #define  DEFAULT_Ki (1.2*Kp/PID_SWING_AT_CRITIAL*PID_dT)
-  #define  DEFAULT_Kd (0)
-  
-  #define PID_ADD_EXTRUSION_RATE  
-  #ifdef PID_ADD_EXTRUSION_RATE
-    #define  DEFAULT_Kc (5) //heatingpower=Kc*(e_speed)
-  #endif
-#endif // PIDTEMP
-
-// extruder advance constant (s2/mm3)
-//
-// advance (steps) = STEPS_PER_CUBIC_MM_E * EXTUDER_ADVANCE_K * cubic mm per second ^ 2
-//
-// hooke's law says:		force = k * distance
-// bernoulli's priniciple says:	v ^ 2 / 2 + g . h + pressure / density = constant
-// so: v ^ 2 is proportional to number of steps we advance the extruder
-//#define ADVANCE
-
-#ifdef ADVANCE
-#define EXTRUDER_ADVANCE_K .3
-
-#define D_FILAMENT 1.7
-#define STEPS_MM_E 65
-#define EXTRUTION_AREA (0.25 * D_FILAMENT * D_FILAMENT * 3.14159)
-#define STEPS_PER_CUBIC_MM_E (axis_steps_per_unit[E_AXIS]/ EXTRUTION_AREA)
-
-#endif // ADVANCE
-
-// THE BLOCK_BUFFER_SIZE NEEDS TO BE A POWER OF 2, e.g. 8,16,32 
-#if defined SDSUPPORT
-// The number of linear motions that can be in the plan at any give time.  
-  #define BLOCK_BUFFER_SIZE 16   // SD,LCD,Buttons take more memory, block buffer needs to be smaller
-#else
-  #define BLOCK_BUFFER_SIZE 16 // maximize block buffer
-#endif
-
-
-#endif
+#ifndef CONFIGURATION_H
+#define CONFIGURATION_H
+
+//#define DEBUG_STEPS
+
+#define MM_PER_ARC_SEGMENT 1
+#define N_ARC_CORRECTION 25
+
+// BASIC SETTINGS: select your board type, thermistor type, axis scaling, and endstop configuration
+
+//// The following define selects which electronics board you have. Please choose the one that matches your setup
+// MEGA/RAMPS up to 1.2 = 3,
+// RAMPS 1.3 = 33
+// Gen6 = 5,
+// Sanguinololu 1.2 and above = 62
+// Ultimaker = 7,
+#define MOTHERBOARD 7
+//#define MOTHERBOARD 5
+
+
+//// Thermistor settings:
+// 1 is 100k thermistor
+// 2 is 200k thermistor
+// 3 is mendel-parts thermistor
+// 4 is 10k thermistor
+// 5 is ParCan supplied 104GT-2 100K
+// 6 is EPCOS 100k
+// 7 is 100k Honeywell thermistor 135-104LAG-J01
+#define THERMISTORHEATER_1 3
+#define THERMISTORHEATER_2 3
+#define THERMISTORBED 3
+
+//#define HEATER_0_USES_THERMISTOR
+//#define HEATER_1_USES_THERMISTOR
+#define HEATER_0_USES_AD595
+//#define HEATER_1_USES_AD595
+
+// Select one of these only to define how the bed temp is read.
+//#define BED_USES_THERMISTOR
+//#define BED_USES_AD595
+
+#define HEATER_CHECK_INTERVAL 50
+#define BED_CHECK_INTERVAL 5000
+
+
+//// Endstop Settings
+#define ENDSTOPPULLUPS // Comment this out (using // at the start of the line) to disable the endstop pullup resistors
+// The pullups are needed if you directly connect a mechanical endswitch between the signal and ground pins.
+const bool ENDSTOPS_INVERTING = true; // set to true to invert the logic of the endstops. 
+// For optos H21LOB set to true, for Mendel-Parts newer optos TCST2103 set to false
+
+// This determines the communication speed of the printer
+#define BAUDRATE 250000
+//#define BAUDRATE 115200
+//#define BAUDRATE 230400
+
+// Comment out (using // at the start of the line) to disable SD support:
+
+// #define ULTRA_LCD  //any lcd 
+
+#define ULTIPANEL
+#define ULTIPANEL
+#ifdef ULTIPANEL
+ //#define NEWPANEL  //enable this if you have a click-encoder panel
+ #define SDSUPPORT
+ #define ULTRA_LCD
+ #define LCD_WIDTH 20
+#define LCD_HEIGHT 4
+#else //no panel but just lcd 
+  #ifdef ULTRA_LCD
+    #define LCD_WIDTH 16
+    #define LCD_HEIGHT 2
+  #endif
+#endif
+
+
+//#define SDSUPPORT // Enable SD Card Support in Hardware Console
+
+
+
+const int dropsegments=5; //everything with this number of steps  will be ignored as move
+
+//// ADVANCED SETTINGS - to tweak parameters
+
+#include "thermistortables.h"
+
+// For Inverting Stepper Enable Pins (Active Low) use 0, Non Inverting (Active High) use 1
+#define X_ENABLE_ON 0
+#define Y_ENABLE_ON 0
+#define Z_ENABLE_ON 0
+#define E_ENABLE_ON 0
+
+// Disables axis when it's not being used.
+#define DISABLE_X false
+#define DISABLE_Y false
+#define DISABLE_Z false
+#define DISABLE_E false
+
+// Inverting axis direction
+#define INVERT_X_DIR true    // for Mendel set to false, for Orca set to true
+#define INVERT_Y_DIR false   // for Mendel set to true, for Orca set to false
+#define INVERT_Z_DIR true    // for Mendel set to false, for Orca set to true
+#define INVERT_E_DIR false   // for direct drive extruder v9 set to true, for geared extruder set to false
+
+//// ENDSTOP SETTINGS:
+// Sets direction of endstops when homing; 1=MAX, -1=MIN
+#define X_HOME_DIR -1
+#define Y_HOME_DIR -1
+#define Z_HOME_DIR -1
+
+#define min_software_endstops false //If true, axis won't move to coordinates less than zero.
+#define max_software_endstops false  //If true, axis won't move to coordinates greater than the defined lengths below.
+#define X_MAX_LENGTH 210
+#define Y_MAX_LENGTH 210
+#define Z_MAX_LENGTH 210
+
+//// MOVEMENT SETTINGS
+#define NUM_AXIS 4 // The axis order in all axis related arrays is X, Y, Z, E
+//note: on bernhards ultimaker 200 200 12 are working well.
+#define HOMING_FEEDRATE {50*60, 50*60, 12*60, 0}  // set the homing speeds
+//the followint checks if an extrusion is existent in the move. if _not_, the speed of the move is set to the maximum speed. 
+//!!!!!!Use only if you know that your printer works at the maximum declared speeds.
+// works around the skeinforge cool-bug. There all moves are slowed to have a minimum layer time. However slow travel moves= ooze
+#define TRAVELING_AT_MAXSPEED  
+#define AXIS_RELATIVE_MODES {false, false, false, false}
+
+#define MAX_STEP_FREQUENCY 40000 // Max step frequency for Ultimaker (5000 pps / half step)
+
+// default settings 
+
+#define DEFAULT_AXIS_STEPS_PER_UNIT   {79.87220447,79.87220447,200*8/3,14}                    // default steps per unit for ultimaker 
+#define DEFAULT_MAX_FEEDRATE          {160*60, 160*60, 10*60, 500000}        
+#define DEFAULT_MAX_ACCELERATION      {9000,9000,150,10000}    // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for skeinforge 40+, for older versions raise them a lot.
+
+#define DEFAULT_ACCELERATION          3000    // X, Y, Z and E max acceleration in mm/s^2 for printing moves 
+#define DEFAULT_RETRACT_ACCELERATION  7000   // X, Y, Z and E max acceleration in mm/s^2 for r retracts
+
+#define DEFAULT_MINIMUMFEEDRATE       10     // minimum feedrate
+#define DEFAULT_MINTRAVELFEEDRATE     10
+
+// minimum time in microseconds that a movement needs to take if the buffer is emptied.   Increase this number if you see blobs while printing high speed & high detail.  It will slowdown on the detailed stuff.
+#define DEFAULT_MINSEGMENTTIME        20000
+#define DEFAULT_XYJERK                30.0*60    
+#define DEFAULT_ZJERK                 10.0*60
+
+
+// The watchdog waits for the watchperiod in milliseconds whenever an M104 or M109 increases the target temperature
+//this enables the watchdog interrupt.
+#define USE_WATCHDOG
+//you cannot reboot on a mega2560 due to a bug in he bootloader. Hence, you have to reset manually, and this is done hereby:
+#define RESET_MANUAL
+
+#define WATCHDOG_TIMEOUT 4
+
+
+
+//// Experimental watchdog and minimal temp
+// The watchdog waits for the watchperiod in milliseconds whenever an M104 or M109 increases the target temperature
+// If the temperature has not increased at the end of that period, the target temperature is set to zero. It can be reset with another M104/M109
+//#define WATCHPERIOD 5000 //5 seconds
+
+// Actual temperature must be close to target for this long before M109 returns success
+//#define TEMP_RESIDENCY_TIME 20  // (seconds)
+//#define TEMP_HYSTERESIS 5       // (C°) range of +/- temperatures considered "close" to the target one
+
+//// The minimal temperature defines the temperature below which the heater will not be enabled
+#define HEATER_0_MINTEMP 5
+//#define HEATER_1_MINTEMP 5
+//#define BED_MINTEMP 5
+
+
+// When temperature exceeds max temp, your heater will be switched off.
+// This feature exists to protect your hotend from overheating accidentally, but *NOT* from thermistor short/failure!
+// You should use MINTEMP for thermistor short/failure protection.
+#define HEATER_0_MAXTEMP 275
+//#define_HEATER_1_MAXTEMP 275
+//#define BED_MAXTEMP 150
+
+
+
+
+
+
+
+#define PIDTEMP
+#ifdef PIDTEMP
+  /// PID settings:
+  // Uncomment the following line to enable PID support.
+  //#define SMOOTHING
+  //#define SMOOTHFACTOR 5.0
+  //float current_raw_average=0;
+    #define K1 0.95 //smoothing of the PID
+  //#define PID_DEBUG // Sends debug data to the serial port. 
+  //#define PID_OPENLOOP 1 // Puts PID in open loop. M104 sets the output power in %
+  #define PID_MAX 255 // limits current to nozzle
+  #define PID_INTEGRAL_DRIVE_MAX 255
+  #define PID_dT 0.1
+ //machine with red silicon: 1950:45 second ; with fan fully blowin 3000:47
+
+  #define PID_CRITIAL_GAIN 3000
+  #define PID_SWING_AT_CRITIAL 45 //seconds
+  #define PIDIADD 5
+  /*
+  //PID according to Ziegler-Nichols method
+  float Kp = 0.6*PID_CRITIAL_GAIN; 
+  float Ki =PIDIADD+2*Kp/PID_SWING_AT_CRITIAL*PID_dT;  
+  float Kd = Kp*PID_SWING_AT_CRITIAL/8./PID_dT;  
+  */
+  //PI according to Ziegler-Nichols method
+  #define  DEFAULT_Kp (PID_CRITIAL_GAIN/2.2) 
+  #define  DEFAULT_Ki (1.2*Kp/PID_SWING_AT_CRITIAL*PID_dT)
+  #define  DEFAULT_Kd (0)
+  
+  #define PID_ADD_EXTRUSION_RATE  
+  #ifdef PID_ADD_EXTRUSION_RATE
+    #define  DEFAULT_Kc (5) //heatingpower=Kc*(e_speed)
+  #endif
+#endif // PIDTEMP
+
+// extruder advance constant (s2/mm3)
+//
+// advance (steps) = STEPS_PER_CUBIC_MM_E * EXTUDER_ADVANCE_K * cubic mm per second ^ 2
+//
+// hooke's law says:		force = k * distance
+// bernoulli's priniciple says:	v ^ 2 / 2 + g . h + pressure / density = constant
+// so: v ^ 2 is proportional to number of steps we advance the extruder
+//#define ADVANCE
+
+#ifdef ADVANCE
+#define EXTRUDER_ADVANCE_K .3
+
+#define D_FILAMENT 1.7
+#define STEPS_MM_E 65
+#define EXTRUTION_AREA (0.25 * D_FILAMENT * D_FILAMENT * 3.14159)
+#define STEPS_PER_CUBIC_MM_E (axis_steps_per_unit[E_AXIS]/ EXTRUTION_AREA)
+
+#endif // ADVANCE
+
+// THE BLOCK_BUFFER_SIZE NEEDS TO BE A POWER OF 2, e.g. 8,16,32 
+#if defined SDSUPPORT
+// The number of linear motions that can be in the plan at any give time.  
+  #define BLOCK_BUFFER_SIZE 16   // SD,LCD,Buttons take more memory, block buffer needs to be smaller
+#else
+  #define BLOCK_BUFFER_SIZE 16 // maximize block buffer
+#endif
+
+
+#endif

Marlin/motion_control.cpp

@@ -0,0 +1,133 @@
+/*
+  motion_control.c - high level interface for issuing motion commands
+  Part of Grbl
+
+  Copyright (c) 2009-2011 Simen Svale Skogsrud
+  Copyright (c) 2011 Sungeun K. Jeon
+  
+  Grbl is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  Grbl is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with Grbl.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+//#include "motion_control.h"
+#include "Configuration.h"
+#include "Marlin.h"
+//#include <util/delay.h>
+//#include <math.h>
+//#include <stdlib.h>
+#include "stepper.h"
+#include "planner.h"
+
+// The arc is approximated by generating a huge number of tiny, linear segments. The length of each 
+// segment is configured in settings.mm_per_arc_segment.  
+void mc_arc(float *position, float *target, float *offset, uint8_t axis_0, uint8_t axis_1, 
+  uint8_t axis_linear, float feed_rate, float radius, uint8_t isclockwise)
+{      
+//   int acceleration_manager_was_enabled = plan_is_acceleration_manager_enabled();
+//   plan_set_acceleration_manager_enabled(false); // disable acceleration management for the duration of the arc
+  Serial.println("mc_arc");
+  float center_axis0 = position[axis_0] + offset[axis_0];
+  float center_axis1 = position[axis_1] + offset[axis_1];
+  float linear_travel = target[axis_linear] - position[axis_linear];
+  float r_axis0 = -offset[axis_0];  // Radius vector from center to current location
+  float r_axis1 = -offset[axis_1];
+  float rt_axis0 = target[axis_0] - center_axis0;
+  float rt_axis1 = target[axis_1] - center_axis1;
+  
+  // CCW angle between position and target from circle center. Only one atan2() trig computation required.
+  float angular_travel = atan2(r_axis0*rt_axis1-r_axis1*rt_axis0, r_axis0*rt_axis0+r_axis1*rt_axis1);
+  if (angular_travel < 0) { angular_travel += 2*M_PI; }
+  if (isclockwise) { angular_travel -= 2*M_PI; }
+  
+  float millimeters_of_travel = hypot(angular_travel*radius, fabs(linear_travel));
+  if (millimeters_of_travel == 0.0) { return; }
+  uint16_t segments = floor(millimeters_of_travel/MM_PER_ARC_SEGMENT);
+/*  
+  // Multiply inverse feed_rate to compensate for the fact that this movement is approximated
+  // by a number of discrete segments. The inverse feed_rate should be correct for the sum of 
+  // all segments.
+  if (invert_feed_rate) { feed_rate *= segments; }
+*/
+  float theta_per_segment = angular_travel/segments;
+  float linear_per_segment = linear_travel/segments;
+  
+  /* Vector rotation by transformation matrix: r is the original vector, r_T is the rotated vector,
+     and phi is the angle of rotation. Based on the solution approach by Jens Geisler.
+         r_T = [cos(phi) -sin(phi);
+                sin(phi)  cos(phi] * r ;
+     
+     For arc generation, the center of the circle is the axis of rotation and the radius vector is 
+     defined from the circle center to the initial position. Each line segment is formed by successive
+     vector rotations. This requires only two cos() and sin() computations to form the rotation
+     matrix for the duration of the entire arc. Error may accumulate from numerical round-off, since
+     all double numbers are single precision on the Arduino. (True double precision will not have
+     round off issues for CNC applications.) Single precision error can accumulate to be greater than
+     tool precision in some cases. Therefore, arc path correction is implemented. 
+
+     Small angle approximation may be used to reduce computation overhead further. This approximation
+     holds for everything, but very small circles and large mm_per_arc_segment values. In other words,
+     theta_per_segment would need to be greater than 0.1 rad and N_ARC_CORRECTION would need to be large
+     to cause an appreciable drift error. N_ARC_CORRECTION~=25 is more than small enough to correct for 
+     numerical drift error. N_ARC_CORRECTION may be on the order a hundred(s) before error becomes an
+     issue for CNC machines with the single precision Arduino calculations.
+     
+     This approximation also allows mc_arc to immediately insert a line segment into the planner 
+     without the initial overhead of computing cos() or sin(). By the time the arc needs to be applied
+     a correction, the planner should have caught up to the lag caused by the initial mc_arc overhead. 
+     This is important when there are successive arc motions. 
+  */
+  // Vector rotation matrix values
+  float cos_T = 1-0.5*theta_per_segment*theta_per_segment; // Small angle approximation
+  float sin_T = theta_per_segment;
+  
+  float arc_target[3];
+  float sin_Ti;
+  float cos_Ti;
+  float r_axisi;
+  uint16_t i;
+  int8_t count = 0;
+
+  // Initialize the linear axis
+  arc_target[axis_linear] = position[axis_linear];
+
+  for (i = 1; i<segments; i++) { // Increment (segments-1)
+    
+    if (count < N_ARC_CORRECTION) {
+      // Apply vector rotation matrix 
+      r_axisi = r_axis0*sin_T + r_axis1*cos_T;
+      r_axis0 = r_axis0*cos_T - r_axis1*sin_T;
+      r_axis1 = r_axisi;
+      count++;
+    } else {
+      // Arc correction to radius vector. Computed only every N_ARC_CORRECTION increments.
+      // Compute exact location by applying transformation matrix from initial radius vector(=-offset).
+      cos_Ti = cos(i*theta_per_segment);
+      sin_Ti = sin(i*theta_per_segment);
+      r_axis0 = -offset[axis_0]*cos_Ti + offset[axis_1]*sin_Ti;
+      r_axis1 = -offset[axis_0]*sin_Ti - offset[axis_1]*cos_Ti;
+      count = 0;
+    }
+
+    // Update arc_target location
+    arc_target[axis_0] = center_axis0 + r_axis0;
+    arc_target[axis_1] = center_axis1 + r_axis1;
+    arc_target[axis_linear] += linear_per_segment;
+    plan_buffer_line(arc_target[X_AXIS], arc_target[Y_AXIS], arc_target[Z_AXIS], target[E_AXIS], feed_rate);
+    
+  }
+  // Ensure last segment arrives at target location.
+  plan_buffer_line(target[X_AXIS], target[Y_AXIS], target[Z_AXIS], target[E_AXIS], feed_rate);
+
+//   plan_set_acceleration_manager_enabled(acceleration_manager_was_enabled);
+}
+

Marlin/motion_control.h

@@ -0,0 +1,32 @@
+/*
+  motion_control.h - high level interface for issuing motion commands
+  Part of Grbl
+
+  Copyright (c) 2009-2011 Simen Svale Skogsrud
+  Copyright (c) 2011 Sungeun K. Jeon
+  
+  Grbl is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  Grbl is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with Grbl.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef motion_control_h
+#define motion_control_h
+
+// Execute an arc in offset mode format. position == current xyz, target == target xyz, 
+// offset == offset from current xyz, axis_XXX defines circle plane in tool space, axis_linear is
+// the direction of helical travel, radius == circle radius, isclockwise boolean. Used
+// for vector transformation direction.
+void mc_arc(float *position, float *target, float *offset, unsigned char axis_0, unsigned char axis_1,
+  unsigned char axis_linear, float feed_rate, float radius, unsigned char isclockwise);
+  
+#endif