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planner.h - buffers movement commands and manages the acceleration profile plan
Part of Grbl
Copyright (c) 2009-2011 Simen Svale Skogsrud
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
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 <>.
// This module is to be considered a sub-module of stepper.c. Please don't include
// this file from any other module.
#ifndef planner_h
#define planner_h
#include "Marlin.h"
// This struct is used when buffering the setup for each linear movement "nominal" values are as specified in
// the source g-code and may never actually be reached if acceleration management is active.
typedef struct {
// Fields used by the bresenham algorithm for tracing the line
long steps_x, steps_y, steps_z, steps_e; // Step count along each axis
unsigned long step_event_count; // The number of step events required to complete this block
long accelerate_until; // The index of the step event on which to stop acceleration
long decelerate_after; // The index of the step event on which to start decelerating
long acceleration_rate; // The acceleration rate used for acceleration calculation
unsigned char direction_bits; // The direction bit set for this block (refers to *_DIRECTION_BIT in config.h)
unsigned char active_extruder; // Selects the active extruder
#ifdef ADVANCE
long advance_rate;
volatile long initial_advance;
volatile long final_advance;
float advance;
// Fields used by the motion planner to manage acceleration
// float speed_x, speed_y, speed_z, speed_e; // Nominal mm/sec for each axis
float nominal_speed; // The nominal speed for this block in mm/sec
float entry_speed; // Entry speed at previous-current junction in mm/sec
float max_entry_speed; // Maximum allowable junction entry speed in mm/sec
float millimeters; // The total travel of this block in mm
float acceleration; // acceleration mm/sec^2
unsigned char recalculate_flag; // Planner flag to recalculate trapezoids on entry junction
unsigned char nominal_length_flag; // Planner flag for nominal speed always reached
// Settings for the trapezoid generator
unsigned long nominal_rate; // The nominal step rate for this block in step_events/sec
unsigned long initial_rate; // The jerk-adjusted step rate at start of block
unsigned long final_rate; // The minimal rate at exit
unsigned long acceleration_st; // acceleration steps/sec^2
unsigned long fan_speed;
volatile char busy;
} block_t;
// Initialize the motion plan subsystem
void plan_init();
// Add a new linear movement to the buffer. x, y and z is the signed, absolute target position in
// millimaters. Feed rate specifies the speed of the motion.
void plan_buffer_line(const float &x, const float &y, const float &z, const float &e, float feed_rate, const uint8_t &extruder);
// Set position. Used for G92 instructions.
void plan_set_position(const float &x, const float &y, const float &z, const float &e);
void plan_set_e_position(const float &e);
void check_axes_activity();
uint8_t movesplanned(); //return the nr of buffered moves
extern unsigned long minsegmenttime;
extern float max_feedrate[4]; // set the max speeds
extern float axis_steps_per_unit[4];
extern unsigned long max_acceleration_units_per_sq_second[4]; // Use M201 to override by software
extern float minimumfeedrate;
extern float acceleration; // Normal acceleration mm/s^2 THIS IS THE DEFAULT ACCELERATION for all moves. M204 SXXXX
extern float retract_acceleration; // mm/s^2 filament pull-pack and push-forward while standing still in the other axis M204 TXXXX
extern float max_xy_jerk; //speed than can be stopped at once, if i understand correctly.
extern float max_z_jerk;
extern float max_e_jerk;
extern float mintravelfeedrate;
extern unsigned long axis_steps_per_sqr_second[NUM_AXIS];
extern bool autotemp_enabled;
extern float autotemp_max;
extern float autotemp_min;
extern float autotemp_factor;
extern block_t block_buffer[BLOCK_BUFFER_SIZE]; // A ring buffer for motion instfructions
extern volatile unsigned char block_buffer_head; // Index of the next block to be pushed
extern volatile unsigned char block_buffer_tail;
// Called when the current block is no longer needed. Discards the block and makes the memory
// availible for new blocks.
FORCE_INLINE void plan_discard_current_block()
if (block_buffer_head != block_buffer_tail) {
block_buffer_tail = (block_buffer_tail + 1) & (BLOCK_BUFFER_SIZE - 1);
// Gets the current block. Returns NULL if buffer empty
FORCE_INLINE block_t *plan_get_current_block()
if (block_buffer_head == block_buffer_tail) {
block_t *block = &block_buffer[block_buffer_tail];
block->busy = true;
// Gets the current block. Returns NULL if buffer empty
FORCE_INLINE bool blocks_queued()
if (block_buffer_head == block_buffer_tail) {
return false;
return true;
void allow_cold_extrudes(bool allow);
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