355 lines
12 KiB
C
355 lines
12 KiB
C
/*
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motion_control.c - cartesian robot controller.
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Part of Grbl
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Copyright (c) 2009 Simen Svale Skogsrud
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Grbl is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Grbl is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with Grbl. If not, see <http://www.gnu.org/licenses/>.
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*/
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/* The structure of this module was inspired by the Arduino GCode_Interpreter by Mike Ellery. The arc
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interpolator written from the information provided in the Wikipedia article 'Midpoint circle algorithm'
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and the lecture 'Circle Drawing Algorithms' by Leonard McMillan.
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http://en.wikipedia.org/wiki/Midpoint_circle_algorithm
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http://www.cs.unc.edu/~mcmillan/comp136/Lecture7/circle.html
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*/
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#include <avr/io.h>
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#include "config.h"
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#include "motion_control.h"
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#include <util/delay.h>
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#include <math.h>
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#include <stdlib.h>
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#include "nuts_bolts.h"
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#include "stepper.h"
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// position represents the current position of the head measured in steps
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// target is the target for the current linear motion
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// step_count contains the absolute values of the steps to travel along each axis
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// direction is the sign of the motion for each axis (-1: reverse, 0: standby, 1: forward)
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#define MODE_AT_REST 0
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#define MODE_LINEAR 1
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#define MODE_ARC 2
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#define MODE_DWELL 3
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#define MODE_HOME 4
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#define PHASE_HOME_RETURN 0
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#define PHASE_HOME_NUDGE 1
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#define ONE_MINUTE_OF_MICROSECONDS 60000000
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// Parameters when mode is MODE_ARC
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struct LinearMotionParameters {
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int8_t direction[3]; // The direction of travel along each axis (-1, 0 or 1)
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uint16_t feed_rate;
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int32_t target[3], // The target position in absolute steps
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step_count[3], // Absolute steps of travel along each axis
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counter[3], // A counter used in the bresenham algorithm for line plotting
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maximum_steps; // The larges absolute step-count of any axis
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};
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struct ArcMotionParameters {
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int8_t angular_direction; // 1 = clockwise, -1 = anticlockwise
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uint32_t circle_x, circle_y, target_x, target_y; // current position and target position in the
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// local coordinate system of the circle where [0,0] is the
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// center of the circle.
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int32_t error, x2, y2; // error is always == (circle_x**2 + circle_y**2 - radius**2),
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// x2 is always 2*x, y2 is always 2*y
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uint8_t axis_x, axis_y; // maps the circle axes to stepper axes
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int32_t target[3]; // The target position in absolute steps
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};
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/* The whole state of the motion-control-system in one struct. Makes the code a little bit hard to
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read, but lets us initialize the state of the system by just clearing a single, contigous block of memory.
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By overlaying the variables of the different modes in a union we save a few bytes of precious SRAM.
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*/
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struct MotionControlState {
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int8_t mode; // The current operation mode
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int32_t position[3]; // The current position of the tool in absolute steps
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int32_t pace; // Microseconds between each update in the current mode
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union {
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struct LinearMotionParameters linear; // variables used in MODE_LINEAR
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struct ArcMotionParameters arc; // variables used in MODE_ARC
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uint32_t dwell_milliseconds; // variable used in MODE_DWELL
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};
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};
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struct MotionControlState state;
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uint8_t direction_bits; // The direction bits to be used with any upcoming step-instruction
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void enable_steppers();
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void disable_steppers();
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void set_direction_bits(int8_t *direction);
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inline void step_steppers(uint8_t *enabled);
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inline void step_axis(uint8_t axis);
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void mc_init()
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{
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// Initialize state variables
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memset(&state, 0, sizeof(state));
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}
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void mc_dwell(uint32_t milliseconds)
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{
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st_synchronize();
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state.mode = MODE_DWELL;
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state.dwell_milliseconds = milliseconds;
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state.pace = 1000;
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}
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void mc_linear_motion(double x, double y, double z, float feed_rate, int invert_feed_rate)
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{
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state.mode = MODE_LINEAR;
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state.linear.target[X_AXIS] = trunc(x*X_STEPS_PER_MM);
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state.linear.target[Y_AXIS] = trunc(y*Y_STEPS_PER_MM);
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state.linear.target[Z_AXIS] = trunc(z*Z_STEPS_PER_MM);
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uint8_t axis; // loop variable
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// Determine direction and travel magnitude for each axis
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for(axis = X_AXIS; axis <= Z_AXIS; axis++) {
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state.linear.step_count[axis] = abs(state.linear.target[axis] - state.position[axis]);
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state.linear.direction[axis] = sign(state.linear.step_count[axis]);
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}
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// Find the magnitude of the axis with the longest travel
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state.linear.maximum_steps = max(state.linear.step_count[Z_AXIS],
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max(state.linear.step_count[X_AXIS], state.linear.step_count[Y_AXIS]));
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// Set up a neat counter for each axis
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for(axis = X_AXIS; axis <= Z_AXIS; axis++) {
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state.linear.counter[axis] = -state.linear.maximum_steps/2;
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}
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// Set our direction pins
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set_direction_bits(state.linear.direction);
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// Calculate the microseconds we need to wait between each step to achieve the desired feed rate
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if (invert_feed_rate) {
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state.pace =
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(feed_rate*1000000)/state.linear.maximum_steps;
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} else {
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// Ask old Phytagoras how many millimeters our next move is going to take us:
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float millimeters_of_travel =
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sqrt(pow((X_STEPS_PER_MM*state.linear.step_count[X_AXIS]),2) +
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pow((Y_STEPS_PER_MM*state.linear.step_count[Y_AXIS]),2) +
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pow((Z_STEPS_PER_MM*state.linear.step_count[Z_AXIS]),2));
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state.pace =
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((millimeters_of_travel * ONE_MINUTE_OF_MICROSECONDS) / feed_rate) / state.linear.maximum_steps;
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}
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}
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void perform_linear_motion()
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{
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// Flags to keep track of which axes to step
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uint8_t step[3];
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uint8_t axis; // loop variable
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// Trace the line
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clear_vector(step);
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for(axis = X_AXIS; axis <= Z_AXIS; axis++) {
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if (state.linear.target[axis] != state.position[axis])
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{
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state.linear.counter[axis] += state.linear.step_count[axis];
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if (state.linear.counter[axis] > 0)
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{
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step[axis] = true;
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state.linear.counter[axis] -= state.linear.maximum_steps;
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state.position[axis] += state.linear.direction[axis];
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}
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}
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}
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if (step[X_AXIS] | step[Y_AXIS] | step[Z_AXIS]) {
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step_steppers(step);
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} else {
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state.mode = MODE_AT_REST;
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}
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}
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void mc_arc(double theta, double angular_travel, double radius, uint32_t *target)
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{
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state.mode = MODE_ARC;
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// Calculate the initial position and target position in the local coordinate system of the circle
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state.arc.circle_x = round(sin(theta)*radius);
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state.arc.circle_y = round(cos(theta)*radius);
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state.arc.target_x = trunc(sin(theta+angular_travel)*(radius-0.5));
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state.arc.target_y = trunc(cos(theta+angular_travel)*(radius-0.5));
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// Determine angular direction (+1 = clockwise, -1 = counterclockwise)
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state.arc.angular_direction = sign(angular_travel);
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// The "error" factor is kept up to date so that it is always == (x**2+y**2-radius**2). When error
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// <0 we are inside the circle, when it is >0 we are outside of the circle, and when it is 0 we
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// are exactly on top of the circle.
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state.arc.error = round(pow(state.arc.circle_x,2) + pow(state.arc.circle_y,2) - pow(radius,2));
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// Because the error-value moves in steps of (+/-)2x+1 and (+/-)2y+1 we save a couple of multiplications
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// by keeping track of the doubles of the circle coordinates at all times.
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state.arc.x2 = 2*state.arc.circle_x;
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state.arc.y2 = 2*state.arc.circle_y;
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}
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void step_arc_along_x(dx,dy)
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{
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uint32_t diagonal_error;
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state.arc.circle_x+=dx;
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state.arc.error += 1+state.arc.x2*dx;
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state.arc.x2 += 2*dx;
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diagonal_error = state.arc.error + 1 + state.arc.y2*dy;
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if(abs(state.arc.error) < abs(diagonal_error)) {
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state.arc.circle_y += dy;
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state.arc.y2 += 2*dy;
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state.arc.error = diagonal_error;
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};
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}
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void step_arc_along_y(dx,dy)
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{
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uint32_t diagonal_error;
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state.arc.circle_y+=dy;
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state.arc.error += 1+state.arc.y2*dy;
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state.arc.y2 += 2*dy;
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diagonal_error = state.arc.error + 1 + state.arc.x2*dx;
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if(abs(state.arc.error) < abs(diagonal_error)) {
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state.arc.circle_x += dx;
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state.arc.x2 += 2*dx;
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state.arc.error = diagonal_error;
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}
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}
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/*
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Quandrants of the circle
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\ 7|0 /
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\ | /
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6 \|/ 1 y+
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---------|-----------
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5 /|\ 2 y-
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/ | \
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x- / 4|3 \ x+ */
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int quadrant(uint32_t x,uint32_t y)
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{
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// determine if the coordinate is in the quadrants 0,3,4 or 7
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register int quad0347 = abs(x)<abs(y);
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if (x<0) { // quad 4567
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if (y<0) { // quad 45
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return(quad0347 ? 4 : 5);
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} else { // quad 67
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return(quad0347 ? 7 : 6);
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}
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} else {
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if (y<0) { // quad 23
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return(quad0347 ? 3 : 2);
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} else { // quad 01
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return(quad0347 ? 0 : 1);
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}
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}
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}
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void perform_arc()
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{
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int q = quadrant(state.arc.circle_x, state.arc.circle_y);
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if (state.arc.angular_direction) {
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switch (q) {
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case 0: while(state.arc.circle_x>state.arc.circle_y) { step_arc_along_x(1,-1); }
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case 1: while(state.arc.circle_y>0) { step_arc_along_y(1,-1); }
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case 2: while(state.arc.circle_y>-state.arc.circle_x) { step_arc_along_y(-1,-1); }
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case 3: while(state.arc.circle_x>0) { step_arc_along_x(-1,-1); }
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case 4: while(state.arc.circle_y<state.arc.circle_x) { step_arc_along_x(-1,1); }
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case 5: while(state.arc.circle_y<0) { step_arc_along_y(-1,1); }
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case 6: while(state.arc.circle_y<-state.arc.circle_x) { step_arc_along_y(1,1); }
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case 7: while(state.arc.circle_x<0) { step_arc_along_x(1,1); }
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}
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} else {
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switch (q) {
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case 7: while(state.arc.circle_y>-state.arc.circle_x) { step_arc_along_x(-1,-1); }
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case 6: while(state.arc.circle_y>0) { step_arc_along_y(-1,-1); }
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case 5: while(state.arc.circle_y>state.arc.circle_x) { step_arc_along_y(1,-1); }
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case 4: while(state.arc.circle_x<0) { step_arc_along_x(1,-1); }
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case 3: while(state.arc.circle_y<-state.arc.circle_x) { step_arc_along_x(1,1); }
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case 2: while(state.arc.circle_y<0) { step_arc_along_y(1,1); }
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case 1: while(state.arc.circle_y<state.arc.circle_x) { step_arc_along_y(-1,1); }
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case 0: while(state.arc.circle_x>0) { step_arc_along_x(-1,1); }
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}
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}
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}
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void mc_go_home()
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{
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state.mode = MODE_HOME;
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}
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void perform_go_home()
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{
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st_go_home();
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clear_vector(state.position); // By definition this is location [0, 0, 0]
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state.mode = MODE_AT_REST;
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}
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void mc_execute() {
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st_set_pace(state.pace);
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while(state.mode) {
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switch(state.mode) {
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case MODE_AT_REST: break;
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case MODE_DWELL: _delay_ms(state.dwell_milliseconds); state.mode = MODE_AT_REST; break;
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case MODE_LINEAR: perform_linear_motion();
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case MODE_HOME: perform_go_home();
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}
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}
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}
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int mc_status()
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{
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return(state.mode);
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}
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// Set the direction pins for the stepper motors according to the provided vector.
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// direction is an array of three 8 bit integers representing the direction of
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// each motor. The values should be -1 (reverse), 0 or 1 (forward).
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void set_direction_bits(int8_t *direction)
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{
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/* Sorry about this convoluted code! It uses the fact that bit 7 of each direction
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int is set when the direction == -1, but is 0 when direction is forward. This
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way we can generate the whole direction bit-mask without doing any comparisions
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or branching. Fast and compact, yet practically unreadable. Sorry sorry sorry.
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*/
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direction_bits = ~(
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((direction[X_AXIS]&128)>>(7-X_DIRECTION_BIT)) |
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((direction[Y_AXIS]&128)>>(7-Y_DIRECTION_BIT)) |
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((direction[Z_AXIS]&128)>>(7-Z_DIRECTION_BIT))
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);
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}
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// Step enabled steppers. Enabled should be an array of three bytes. Each byte represent one
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// stepper motor in the order X, Y, Z. Set the bytes of the steppers you want to step to
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// 1, and the rest to 0.
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inline void step_steppers(uint8_t *enabled)
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{
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st_buffer_step(direction_bits | enabled[X_AXIS]<<X_STEP_BIT | enabled[Y_AXIS]<<Y_STEP_BIT | enabled[Z_AXIS]<<Z_STEP_BIT);
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}
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// Step only one motor
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inline void step_axis(uint8_t axis)
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{
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switch (axis) {
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case X_AXIS: st_buffer_step(direction_bits | (1<<X_STEP_BIT)); break;
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case Y_AXIS: st_buffer_step(direction_bits | (1<<Y_STEP_BIT)); break;
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case Z_AXIS: st_buffer_step(direction_bits | (1<<Z_STEP_BIT)); break;
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}
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}
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