339 lines
11 KiB
C
339 lines
11 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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/* This code was inspired by the Arduino GCode_Interpreter by Mike Ellery. */
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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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// 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 MODE_LIMIT_OVERRUN -1
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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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// Parameters when mode is MODE_LINEAR
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struct ArcMotionParameters {
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uint32_t radius;
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int16_t degrees;
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int ccw;
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};
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struct HomeCycleParameters {
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int8_t direction[3]; // The direction of travel along each axis (-1, 0 or 1)
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int8_t phase; // current phase of the home cycle.
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int8_t away[3]; // a vector of booleans. True for each axis that is still away.
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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 update_delay_us; // 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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struct HomeCycleParameters home; // variables used in MODE_HOME
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uint32_t dwell_milliseconds; // variable used in MODE_DWELL
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int8_t limit_overrun_direction[3]; // variable used in MODE_LIMIT_OVERRUN
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};
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};
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struct MotionControlState state;
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int check_limit_switches();
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void enable_steppers();
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void disable_steppers();
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void set_direction_pins(int8_t *direction);
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inline void step_steppers(uint8_t *enabled);
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void limit_overrun(uint8_t *direction);
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int check_limit_switch(int axis);
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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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// Configure directions of interface pins
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STEP_DDR |= STEP_MASK;
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DIRECTION_DDR |= DIRECTION_MASK;
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LIMIT_DDR &= ~(LIMIT_MASK);
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STEPPERS_ENABLE_DDR |= 1<<STEPPERS_ENABLE_BIT;
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disable_steppers();
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}
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void limit_overrun(uint8_t *direction)
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{
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state.mode = MODE_LIMIT_OVERRUN;
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memcpy(state.limit_overrun_direction, direction, sizeof(state.limit_overrun_direction));
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}
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void mc_dwell(uint32_t milliseconds)
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{
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mc_wait();
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state.mode = MODE_DWELL;
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state.dwell_milliseconds = milliseconds;
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state.update_delay_us = 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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mc_wait();
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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_pins(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.update_delay_us =
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(feed_rate*1000000.0)/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.update_delay_us =
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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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// If we trip any limit switch while moving: Abort, abort!
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if (check_limit_switches()) {
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limit_overrun(state.linear.direction);
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}
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_delay_us(state.update_delay_us);
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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_go_home()
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{
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state.mode = MODE_HOME;
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memset(state.home.direction, -1, sizeof(state.home.direction)); // direction = [-1,-1,-1]
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set_direction_pins(state.home.direction);
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clear_vector(state.home.away);
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}
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void perform_go_home()
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{
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int axis;
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if(state.home.phase == PHASE_HOME_RETURN) {
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// We are running all axes in reverse until all limit switches are tripped
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// Check all limit switches:
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for(axis=X_AXIS; axis <= Z_AXIS; axis++) {
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state.home.away[axis] |= check_limit_switch(axis);
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}
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// Step steppers. First retract along Z-axis. Then X and Y.
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if(state.home.away[Z_AXIS]) {
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step_axis(Z_AXIS);
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} else {
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// Check if all axes are home
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if(!(state.home.away[X_AXIS] || state.home.away[Y_AXIS])) {
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// All axes are home, prepare next phase: to nudge the tool carefully out of the limit switches
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memset(state.home.direction, 1, sizeof(state.home.direction)); // direction = [1,1,1]
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set_direction_pins(state.home.direction);
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state.home.phase == PHASE_HOME_NUDGE;
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return;
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}
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step_steppers(state.home.away);
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}
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} else {
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for(axis=X_AXIS; axis <= Z_AXIS; axis++) {
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if(check_limit_switch(axis)) {
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step_axis(axis);
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return;
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}
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}
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// When this code is reached it means all axes are free of their limit-switches. Complete the cycle and rest:
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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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}
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void mc_execute() {
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enable_steppers();
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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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_delay_us(state.update_delay_us);
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}
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disable_steppers();
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}
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void mc_wait() {
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return; // No concurrency support yet. So waiting for all to pass is moot.
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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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int check_limit_switches()
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{
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// Dual read as crude debounce
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return((LIMIT_PORT & LIMIT_MASK) | (LIMIT_PORT & LIMIT_MASK));
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}
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int check_limit_switch(int axis)
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{
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uint8_t mask = 0;
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switch (axis) {
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case X_AXIS: mask = 1<<X_LIMIT_BIT; break;
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case Y_AXIS: mask = 1<<Y_LIMIT_BIT; break;
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case Z_AXIS: mask = 1<<Z_LIMIT_BIT; break;
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}
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return((LIMIT_PORT&mask) || (LIMIT_PORT&mask));
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}
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void enable_steppers()
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{
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STEPPERS_ENABLE_PORT |= 1<<STEPPERS_ENABLE_BIT;
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}
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void disable_steppers()
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{
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STEPPERS_ENABLE_PORT &= ~(1<<STEPPERS_ENABLE_BIT);
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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_pins(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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uint8_t forward_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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DIRECTION_PORT = DIRECTION_PORT & ~(DIRECTION_MASK) | forward_bits;
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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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STEP_PORT |= enabled[X_AXIS]<<X_STEP_BIT | enabled[Y_AXIS]<<Y_STEP_BIT | enabled[Z_AXIS]<<Z_STEP_BIT;
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_delay_us(5);
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STEP_PORT &= ~STEP_MASK;
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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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uint8_t mask = 0;
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switch (axis) {
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case X_AXIS: mask = 1<<X_STEP_BIT; break;
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case Y_AXIS: mask = 1<<Y_STEP_BIT; break;
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case Z_AXIS: mask = 1<<Z_STEP_BIT; break;
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}
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STEP_PORT &= mask;
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_delay_us(5);
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STEP_PORT &= ~STEP_MASK;
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}
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