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grbl/grbl/limits.c

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/*
limits.c - code pertaining to limit-switches and performing the homing cycle
Part of Grbl
Copyright (c) 2012-2016 Sungeun K. Jeon for Gnea Research LLC
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
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 "grbl.h"
// Homing axis search distance multiplier. Computed by this value times the cycle travel.
#ifndef HOMING_AXIS_SEARCH_SCALAR
#define HOMING_AXIS_SEARCH_SCALAR 1.5 // Must be > 1 to ensure limit switch will be engaged.
#endif
#ifndef HOMING_AXIS_LOCATE_SCALAR
#define HOMING_AXIS_LOCATE_SCALAR 5.0 // Must be > 1 to ensure limit switch is cleared.
#endif
void limits_init()
{
LIMIT_DDR &= ~(LIMIT_MASK); // Set as input pins
#ifdef DISABLE_LIMIT_PIN_PULL_UP
LIMIT_PORT &= ~(LIMIT_MASK); // Normal low operation. Requires external pull-down.
#else
LIMIT_PORT |= (LIMIT_MASK); // Enable internal pull-up resistors. Normal high operation.
#endif
if (bit_istrue(settings.flags,BITFLAG_HARD_LIMIT_ENABLE)) {
LIMIT_PCMSK |= LIMIT_MASK; // Enable specific pins of the Pin Change Interrupt
PCICR |= (1 << LIMIT_INT); // Enable Pin Change Interrupt
} else {
limits_disable();
}
#ifdef ENABLE_SOFTWARE_DEBOUNCE
MCUSR &= ~(1<<WDRF);
WDTCSR |= (1<<WDCE) | (1<<WDE);
WDTCSR = (1<<WDP0); // Set time-out at ~32msec.
#endif
}
// Disables hard limits.
void limits_disable()
{
LIMIT_PCMSK &= ~LIMIT_MASK; // Disable specific pins of the Pin Change Interrupt
PCICR &= ~(1 << LIMIT_INT); // Disable Pin Change Interrupt
}
// Returns limit state as a bit-wise uint8 variable. Each bit indicates an axis limit, where
// triggered is 1 and not triggered is 0. Invert mask is applied. Axes are defined by their
// number in bit position, i.e. Z_AXIS is (1<<2) or bit 2, and Y_AXIS is (1<<1) or bit 1.
uint8_t limits_get_state()
{
uint8_t limit_state = 0;
uint8_t pin = (LIMIT_PIN & LIMIT_MASK);
#ifdef INVERT_LIMIT_PIN_MASK
pin ^= INVERT_LIMIT_PIN_MASK;
#endif
if (bit_isfalse(settings.flags,BITFLAG_INVERT_LIMIT_PINS)) { pin ^= LIMIT_MASK; }
if (pin) {
uint8_t idx;
for (idx=0; idx<N_AXIS; idx++) {
if (pin & get_limit_pin_mask(idx)) { limit_state |= (1 << idx); }
}
}
return(limit_state);
}
// This is the Limit Pin Change Interrupt, which handles the hard limit feature. A bouncing
// limit switch can cause a lot of problems, like false readings and multiple interrupt calls.
// If a switch is triggered at all, something bad has happened and treat it as such, regardless
// if a limit switch is being disengaged. It's impossible to reliably tell the state of a
// bouncing pin without a debouncing method. A simple software debouncing feature may be enabled
// through the config.h file, where an extra timer delays the limit pin read by several milli-
// seconds to help with, not fix, bouncing switches.
// NOTE: Do not attach an e-stop to the limit pins, because this interrupt is disabled during
// homing cycles and will not respond correctly. Upon user request or need, there may be a
// special pinout for an e-stop, but it is generally recommended to just directly connect
// your e-stop switch to the Arduino reset pin, since it is the most correct way to do this.
#ifndef ENABLE_SOFTWARE_DEBOUNCE
ISR(LIMIT_INT_vect) // DEFAULT: Limit pin change interrupt process.
{
// Ignore limit switches if already in an alarm state or in-process of executing an alarm.
// When in the alarm state, Grbl should have been reset or will force a reset, so any pending
// moves in the planner and serial buffers are all cleared and newly sent blocks will be
// locked out until a homing cycle or a kill lock command. Allows the user to disable the hard
// limit setting if their limits are constantly triggering after a reset and move their axes.
if (sys.state != STATE_ALARM) {
if (!(sys_rt_exec_alarm)) {
#ifdef HARD_LIMIT_FORCE_STATE_CHECK
// Check limit pin state.
if (limits_get_state()) {
mc_reset(); // Initiate system kill.
system_set_exec_alarm(EXEC_ALARM_HARD_LIMIT); // Indicate hard limit critical event
}
#else
mc_reset(); // Initiate system kill.
system_set_exec_alarm(EXEC_ALARM_HARD_LIMIT); // Indicate hard limit critical event
#endif
}
}
}
#else // OPTIONAL: Software debounce limit pin routine.
// Upon limit pin change, enable watchdog timer to create a short delay.
ISR(LIMIT_INT_vect) { if (!(WDTCSR & (1<<WDIE))) { WDTCSR |= (1<<WDIE); } }
ISR(WDT_vect) // Watchdog timer ISR
{
WDTCSR &= ~(1<<WDIE); // Disable watchdog timer.
if (sys.state != STATE_ALARM) { // Ignore if already in alarm state.
if (!(sys_rt_exec_alarm)) {
// Check limit pin state.
if (limits_get_state()) {
mc_reset(); // Initiate system kill.
system_set_exec_alarm(EXEC_ALARM_HARD_LIMIT); // Indicate hard limit critical event
}
}
}
}
#endif
// Homes the specified cycle axes, sets the machine position, and performs a pull-off motion after
// completing. Homing is a special motion case, which involves rapid uncontrolled stops to locate
// the trigger point of the limit switches. The rapid stops are handled by a system level axis lock
// mask, which prevents the stepper algorithm from executing step pulses. Homing motions typically
// circumvent the processes for executing motions in normal operation.
// NOTE: Only the abort realtime command can interrupt this process.
// TODO: Move limit pin-specific calls to a general function for portability.
void limits_go_home(uint8_t cycle_mask)
{
if (sys.abort) { return; } // Block if system reset has been issued.
// Initialize plan data struct for homing motion. Spindle and coolant are disabled.
plan_line_data_t plan_data;
plan_line_data_t *pl_data = &plan_data;
memset(pl_data,0,sizeof(plan_line_data_t));
pl_data->condition = (PL_COND_FLAG_SYSTEM_MOTION|PL_COND_FLAG_NO_FEED_OVERRIDE);
#ifdef USE_LINE_NUMBERS
pl_data->line_number = HOMING_CYCLE_LINE_NUMBER;
#endif
// Initialize variables used for homing computations.
uint8_t n_cycle = (2*N_HOMING_LOCATE_CYCLE+1);
uint8_t step_pin[N_AXIS];
float target[N_AXIS];
float max_travel = 0.0;
uint8_t idx;
for (idx=0; idx<N_AXIS; idx++) {
// Initialize step pin masks
step_pin[idx] = get_step_pin_mask(idx);
#ifdef COREXY
if ((idx==A_MOTOR)||(idx==B_MOTOR)) { step_pin[idx] = (get_step_pin_mask(X_AXIS)|get_step_pin_mask(Y_AXIS)); }
#endif
if (bit_istrue(cycle_mask,bit(idx))) {
// Set target based on max_travel setting. Ensure homing switches engaged with search scalar.
// NOTE: settings.max_travel[] is stored as a negative value.
max_travel = max(max_travel,(-HOMING_AXIS_SEARCH_SCALAR)*settings.max_travel[idx]);
}
}
// Set search mode with approach at seek rate to quickly engage the specified cycle_mask limit switches.
bool approach = true;
float homing_rate = settings.homing_seek_rate;
uint8_t limit_state, axislock, n_active_axis;
do {
system_convert_array_steps_to_mpos(target,sys_position);
// Initialize and declare variables needed for homing routine.
axislock = 0;
n_active_axis = 0;
for (idx=0; idx<N_AXIS; idx++) {
// Set target location for active axes and setup computation for homing rate.
if (bit_istrue(cycle_mask,bit(idx))) {
n_active_axis++;
#ifdef COREXY
if (idx == X_AXIS) {
int32_t axis_position = system_convert_corexy_to_y_axis_steps(sys_position);
sys_position[A_MOTOR] = axis_position;
sys_position[B_MOTOR] = -axis_position;
} else if (idx == Y_AXIS) {
int32_t axis_position = system_convert_corexy_to_x_axis_steps(sys_position);
sys_position[A_MOTOR] = sys_position[B_MOTOR] = axis_position;
} else {
sys_position[Z_AXIS] = 0;
}
#else
sys_position[idx] = 0;
#endif
// Set target direction based on cycle mask and homing cycle approach state.
// NOTE: This happens to compile smaller than any other implementation tried.
if (bit_istrue(settings.homing_dir_mask,bit(idx))) {
if (approach) { target[idx] = -max_travel; }
else { target[idx] = max_travel; }
} else {
if (approach) { target[idx] = max_travel; }
else { target[idx] = -max_travel; }
}
// Apply axislock to the step port pins active in this cycle.
axislock |= step_pin[idx];
}
}
homing_rate *= sqrt(n_active_axis); // [sqrt(N_AXIS)] Adjust so individual axes all move at homing rate.
sys.homing_axis_lock = axislock;
// Perform homing cycle. Planner buffer should be empty, as required to initiate the homing cycle.
pl_data->feed_rate = homing_rate; // Set current homing rate.
plan_buffer_line(target, pl_data); // Bypass mc_line(). Directly plan homing motion.
sys.step_control = STEP_CONTROL_EXECUTE_SYS_MOTION; // Set to execute homing motion and clear existing flags.
st_prep_buffer(); // Prep and fill segment buffer from newly planned block.
st_wake_up(); // Initiate motion
do {
if (approach) {
// Check limit state. Lock out cycle axes when they change.
limit_state = limits_get_state();
for (idx=0; idx<N_AXIS; idx++) {
if (axislock & step_pin[idx]) {
if (limit_state & (1 << idx)) {
#ifdef COREXY
if (idx==Z_AXIS) { axislock &= ~(step_pin[Z_AXIS]); }
else { axislock &= ~(step_pin[A_MOTOR]|step_pin[B_MOTOR]); }
#else
axislock &= ~(step_pin[idx]);
#endif
}
}
}
sys.homing_axis_lock = axislock;
}
st_prep_buffer(); // Check and prep segment buffer. NOTE: Should take no longer than 200us.
// Exit routines: No time to run protocol_execute_realtime() in this loop.
if (sys_rt_exec_state & (EXEC_SAFETY_DOOR | EXEC_RESET | EXEC_CYCLE_STOP)) {
uint8_t rt_exec = sys_rt_exec_state;
// Homing failure condition: Reset issued during cycle.
if (rt_exec & EXEC_RESET) { system_set_exec_alarm(EXEC_ALARM_HOMING_FAIL_RESET); }
// Homing failure condition: Safety door was opened.
if (rt_exec & EXEC_SAFETY_DOOR) { system_set_exec_alarm(EXEC_ALARM_HOMING_FAIL_DOOR); }
// Homing failure condition: Limit switch still engaged after pull-off motion
if (!approach && (limits_get_state() & cycle_mask)) { system_set_exec_alarm(EXEC_ALARM_HOMING_FAIL_PULLOFF); }
// Homing failure condition: Limit switch not found during approach.
if (approach && (rt_exec & EXEC_CYCLE_STOP)) { system_set_exec_alarm(EXEC_ALARM_HOMING_FAIL_APPROACH); }
if (sys_rt_exec_alarm) {
mc_reset(); // Stop motors, if they are running.
protocol_execute_realtime();
return;
} else {
// Pull-off motion complete. Disable CYCLE_STOP from executing.
system_clear_exec_state_flag(EXEC_CYCLE_STOP);
break;
}
}
} while (STEP_MASK & axislock);
st_reset(); // Immediately force kill steppers and reset step segment buffer.
delay_ms(settings.homing_debounce_delay); // Delay to allow transient dynamics to dissipate.
// Reverse direction and reset homing rate for locate cycle(s).
approach = !approach;
// After first cycle, homing enters locating phase. Shorten search to pull-off distance.
if (approach) {
max_travel = settings.homing_pulloff*HOMING_AXIS_LOCATE_SCALAR;
homing_rate = settings.homing_feed_rate;
} else {
max_travel = settings.homing_pulloff;
homing_rate = settings.homing_seek_rate;
}
} while (n_cycle-- > 0);
// The active cycle axes should now be homed and machine limits have been located. By
// default, Grbl defines machine space as all negative, as do most CNCs. Since limit switches
// can be on either side of an axes, check and set axes machine zero appropriately. Also,
// set up pull-off maneuver from axes limit switches that have been homed. This provides
// some initial clearance off the switches and should also help prevent them from falsely
// triggering when hard limits are enabled or when more than one axes shares a limit pin.
int32_t set_axis_position;
// Set machine positions for homed limit switches. Don't update non-homed axes.
for (idx=0; idx<N_AXIS; idx++) {
// NOTE: settings.max_travel[] is stored as a negative value.
if (cycle_mask & bit(idx)) {
#ifdef HOMING_FORCE_SET_ORIGIN
set_axis_position = 0;
#else
if ( bit_istrue(settings.homing_dir_mask,bit(idx)) ) {
set_axis_position = lround((settings.max_travel[idx]+settings.homing_pulloff)*settings.steps_per_mm[idx]);
} else {
set_axis_position = lround(-settings.homing_pulloff*settings.steps_per_mm[idx]);
}
#endif
#ifdef COREXY
if (idx==X_AXIS) {
int32_t off_axis_position = system_convert_corexy_to_y_axis_steps(sys_position);
sys_position[A_MOTOR] = set_axis_position + off_axis_position;
sys_position[B_MOTOR] = set_axis_position - off_axis_position;
} else if (idx==Y_AXIS) {
int32_t off_axis_position = system_convert_corexy_to_x_axis_steps(sys_position);
sys_position[A_MOTOR] = off_axis_position + set_axis_position;
sys_position[B_MOTOR] = off_axis_position - set_axis_position;
} else {
sys_position[idx] = set_axis_position;
}
#else
sys_position[idx] = set_axis_position;
#endif
}
}
sys.step_control = STEP_CONTROL_NORMAL_OP; // Return step control to normal operation.
}
// Performs a soft limit check. Called from mc_line() only. Assumes the machine has been homed,
// the workspace volume is in all negative space, and the system is in normal operation.
// NOTE: Used by jogging to limit travel within soft-limit volume.
void limits_soft_check(float *target)
{
if (system_check_travel_limits(target)) {
sys.soft_limit = true;
// Force feed hold if cycle is active. All buffered blocks are guaranteed to be within
// workspace volume so just come to a controlled stop so position is not lost. When complete
// enter alarm mode.
if (sys.state == STATE_CYCLE) {
system_set_exec_state_flag(EXEC_FEED_HOLD);
do {
protocol_execute_realtime();
if (sys.abort) { return; }
} while ( sys.state != STATE_IDLE );
}
mc_reset(); // Issue system reset and ensure spindle and coolant are shutdown.
system_set_exec_alarm(EXEC_ALARM_SOFT_LIMIT); // Indicate soft limit critical event
protocol_execute_realtime(); // Execute to enter critical event loop and system abort
return;
}
}
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