361 lines
15 KiB
C
361 lines
15 KiB
C
/*
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limits.c - code pertaining to limit-switches and performing the homing cycle
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Part of Grbl
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Copyright (c) 2012-2016 Sungeun K. Jeon for Gnea Research LLC
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Copyright (c) 2009-2011 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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#include "grbl.h"
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// Homing axis search distance multiplier. Computed by this value times the cycle travel.
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#ifndef HOMING_AXIS_SEARCH_SCALAR
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#define HOMING_AXIS_SEARCH_SCALAR 1.5 // Must be > 1 to ensure limit switch will be engaged.
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#endif
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#ifndef HOMING_AXIS_LOCATE_SCALAR
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#define HOMING_AXIS_LOCATE_SCALAR 5.0 // Must be > 1 to ensure limit switch is cleared.
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#endif
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void limits_init()
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{
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LIMIT_DDR &= ~(LIMIT_MASK); // Set as input pins
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#ifdef DISABLE_LIMIT_PIN_PULL_UP
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LIMIT_PORT &= ~(LIMIT_MASK); // Normal low operation. Requires external pull-down.
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#else
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LIMIT_PORT |= (LIMIT_MASK); // Enable internal pull-up resistors. Normal high operation.
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#endif
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if (bit_istrue(settings.flags,BITFLAG_HARD_LIMIT_ENABLE)) {
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//LIMIT_PCMSK |= LIMIT_MASK; // Enable specific pins of the Pin Change Interrupt
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//PCICR |= (1 << LIMIT_INT); // Enable Pin Change Interrupt
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} else {
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limits_disable();
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}
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#ifdef ENABLE_SOFTWARE_DEBOUNCE
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MCUSR &= ~(1<<WDRF);
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WDTCSR |= (1<<WDCE) | (1<<WDE);
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WDTCSR = (1<<WDP0); // Set time-out at ~32msec.
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#endif
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}
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// Disables hard limits.
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void limits_disable()
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{
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//LIMIT_PCMSK &= ~LIMIT_MASK; // Disable specific pins of the Pin Change Interrupt
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//PCICR &= ~(1 << LIMIT_INT); // Disable Pin Change Interrupt
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}
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// Returns limit state as a bit-wise uint8 variable. Each bit indicates an axis limit, where
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// triggered is 1 and not triggered is 0. Invert mask is applied. Axes are defined by their
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// number in bit position, i.e. Z_AXIS is (1<<2) or bit 2, and Y_AXIS is (1<<1) or bit 1.
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uint8_t limits_get_state()
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{
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uint8_t limit_state = 0;
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uint32_t pin = (LIMIT_PIN & LIMIT_MASK);
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#ifdef INVERT_LIMIT_PIN_MASK
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pin ^= INVERT_LIMIT_PIN_MASK;
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#endif
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if (bit_isfalse(settings.flags,BITFLAG_INVERT_LIMIT_PINS)) { pin ^= LIMIT_MASK; }
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if (pin) {
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uint8_t idx;
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for (idx=0; idx<N_AXIS; idx++) {
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if (pin & get_limit_pin_mask(idx)) { limit_state |= (1 << idx); }
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}
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}
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return(limit_state);
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}
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// This is the Limit Pin Change Interrupt, which handles the hard limit feature. A bouncing
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// limit switch can cause a lot of problems, like false readings and multiple interrupt calls.
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// If a switch is triggered at all, something bad has happened and treat it as such, regardless
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// if a limit switch is being disengaged. It's impossible to reliably tell the state of a
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// bouncing pin because the Arduino microcontroller does not retain any state information when
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// detecting a pin change. If we poll the pins in the ISR, you can miss the correct reading if the
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// switch is bouncing.
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// NOTE: Do not attach an e-stop to the limit pins, because this interrupt is disabled during
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// homing cycles and will not respond correctly. Upon user request or need, there may be a
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// special pinout for an e-stop, but it is generally recommended to just directly connect
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// your e-stop switch to the Arduino reset pin, since it is the most correct way to do this.
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#ifndef ENABLE_SOFTWARE_DEBOUNCE
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ISR(LIMIT_INT_vect) // DEFAULT: Limit pin change interrupt process.
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{
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// Ignore limit switches if already in an alarm state or in-process of executing an alarm.
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// When in the alarm state, Grbl should have been reset or will force a reset, so any pending
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// moves in the planner and serial buffers are all cleared and newly sent blocks will be
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// locked out until a homing cycle or a kill lock command. Allows the user to disable the hard
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// limit setting if their limits are constantly triggering after a reset and move their axes.
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if (sys.state != STATE_ALARM) {
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if (!(sys_rt_exec_alarm)) {
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#ifdef HARD_LIMIT_FORCE_STATE_CHECK
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// Check limit pin state.
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if (limits_get_state()) {
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mc_reset(); // Initiate system kill.
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system_set_exec_alarm(EXEC_ALARM_HARD_LIMIT); // Indicate hard limit critical event
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}
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#else
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mc_reset(); // Initiate system kill.
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system_set_exec_alarm(EXEC_ALARM_HARD_LIMIT); // Indicate hard limit critical event
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#endif
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}
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}
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}
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#else // OPTIONAL: Software debounce limit pin routine.
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// Upon limit pin change, enable watchdog timer to create a short delay.
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ISR(LIMIT_INT_vect) { if (!(WDTCSR & (1<<WDIE))) { WDTCSR |= (1<<WDIE); } }
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ISR(WDT_vect) // Watchdog timer ISR
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{
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WDTCSR &= ~(1<<WDIE); // Disable watchdog timer.
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if (sys.state != STATE_ALARM) { // Ignore if already in alarm state.
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if (!(sys_rt_exec_alarm)) {
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// Check limit pin state.
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if (limits_get_state()) {
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mc_reset(); // Initiate system kill.
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system_set_exec_alarm(EXEC_ALARM_HARD_LIMIT); // Indicate hard limit critical event
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}
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}
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}
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}
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#endif
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// Homes the specified cycle axes, sets the machine position, and performs a pull-off motion after
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// completing. Homing is a special motion case, which involves rapid uncontrolled stops to locate
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// the trigger point of the limit switches. The rapid stops are handled by a system level axis lock
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// mask, which prevents the stepper algorithm from executing step pulses. Homing motions typically
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// circumvent the processes for executing motions in normal operation.
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// NOTE: Only the abort realtime command can interrupt this process.
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// TODO: Move limit pin-specific calls to a general function for portability.
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void limits_go_home(uint8_t cycle_mask)
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{
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if (sys.abort) { return; } // Block if system reset has been issued.
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// Initialize plan data struct for homing motion. Spindle and coolant are disabled.
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plan_line_data_t plan_data;
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plan_line_data_t *pl_data = &plan_data;
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memset(pl_data,0,sizeof(plan_line_data_t));
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pl_data->condition = (PL_COND_FLAG_SYSTEM_MOTION|PL_COND_FLAG_NO_FEED_OVERRIDE);
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#ifdef USE_LINE_NUMBERS
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pl_data->line_number = HOMING_CYCLE_LINE_NUMBER;
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#endif
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// Initialize variables used for homing computations.
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uint8_t n_cycle = (2*N_HOMING_LOCATE_CYCLE+1);
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uint32_t step_pin[N_AXIS];
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float target[N_AXIS];
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float max_travel = 0.0;
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uint8_t idx;
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for (idx=0; idx<N_AXIS; idx++) {
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// Initialize step pin masks
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step_pin[idx] = get_step_pin_mask(idx);
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#ifdef COREXY
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if ((idx==A_MOTOR)||(idx==B_MOTOR)) { step_pin[idx] = (get_step_pin_mask(X_AXIS)|get_step_pin_mask(Y_AXIS)); }
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#endif
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if (bit_istrue(cycle_mask,bit(idx))) {
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// Set target based on max_travel setting. Ensure homing switches engaged with search scalar.
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// NOTE: settings.max_travel[] is stored as a negative value.
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max_travel = max(max_travel,(-HOMING_AXIS_SEARCH_SCALAR)*settings.max_travel[idx]);
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}
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}
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// Set search mode with approach at seek rate to quickly engage the specified cycle_mask limit switches.
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bool approach = true;
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float homing_rate = settings.homing_seek_rate;
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uint32_t limit_state, axislock, n_active_axis;
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do {
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system_convert_array_steps_to_mpos(target,sys_position);
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// Initialize and declare variables needed for homing routine.
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axislock = 0;
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n_active_axis = 0;
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for (idx=0; idx<N_AXIS; idx++) {
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// Set target location for active axes and setup computation for homing rate.
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if (bit_istrue(cycle_mask,bit(idx))) {
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n_active_axis++;
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#ifdef COREXY
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if (idx == X_AXIS) {
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int32_t axis_position = system_convert_corexy_to_y_axis_steps(sys_position);
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sys_position[A_MOTOR] = axis_position;
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sys_position[B_MOTOR] = -axis_position;
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} else if (idx == Y_AXIS) {
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int32_t axis_position = system_convert_corexy_to_x_axis_steps(sys_position);
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sys_position[A_MOTOR] = sys_position[B_MOTOR] = axis_position;
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} else {
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sys_position[Z_AXIS] = 0;
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}
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#else
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sys_position[idx] = 0;
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#endif
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// Set target direction based on cycle mask and homing cycle approach state.
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// NOTE: This happens to compile smaller than any other implementation tried.
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if (bit_istrue(settings.homing_dir_mask,bit(idx))) {
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if (approach) { target[idx] = -max_travel; }
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else { target[idx] = max_travel; }
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} else {
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if (approach) { target[idx] = max_travel; }
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else { target[idx] = -max_travel; }
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}
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// Apply axislock to the step port pins active in this cycle.
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axislock |= step_pin[idx];
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}
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}
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homing_rate *= sqrt(n_active_axis); // [sqrt(N_AXIS)] Adjust so individual axes all move at homing rate.
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sys.homing_axis_lock = axislock;
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// Perform homing cycle. Planner buffer should be empty, as required to initiate the homing cycle.
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pl_data->feed_rate = homing_rate; // Set current homing rate.
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plan_buffer_line(target, pl_data); // Bypass mc_line(). Directly plan homing motion.
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sys.step_control = STEP_CONTROL_EXECUTE_SYS_MOTION; // Set to execute homing motion and clear existing flags.
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st_prep_buffer(); // Prep and fill segment buffer from newly planned block.
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st_wake_up(); // Initiate motion
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do {
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if (approach) {
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// Check limit state. Lock out cycle axes when they change.
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limit_state = limits_get_state();
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for (idx=0; idx<N_AXIS; idx++) {
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if (axislock & step_pin[idx]) {
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if (limit_state & (1 << idx)) {
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#ifdef COREXY
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if (idx==Z_AXIS) { axislock &= ~(step_pin[Z_AXIS]); }
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else { axislock &= ~(step_pin[A_MOTOR]|step_pin[B_MOTOR]); }
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#else
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axislock &= ~(step_pin[idx]);
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#endif
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}
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}
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}
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sys.homing_axis_lock = axislock;
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}
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st_prep_buffer(); // Check and prep segment buffer. NOTE: Should take no longer than 200us.
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// Exit routines: No time to run protocol_execute_realtime() in this loop.
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if (sys_rt_exec_state & (EXEC_SAFETY_DOOR | EXEC_RESET | EXEC_CYCLE_STOP)) {
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uint8_t rt_exec = sys_rt_exec_state;
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// Homing failure condition: Reset issued during cycle.
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if (rt_exec & EXEC_RESET) { system_set_exec_alarm(EXEC_ALARM_HOMING_FAIL_RESET); }
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// Homing failure condition: Safety door was opened.
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if (rt_exec & EXEC_SAFETY_DOOR) { system_set_exec_alarm(EXEC_ALARM_HOMING_FAIL_DOOR); }
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// Homing failure condition: Limit switch still engaged after pull-off motion
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if (!approach && (limits_get_state() & cycle_mask)) { system_set_exec_alarm(EXEC_ALARM_HOMING_FAIL_PULLOFF); }
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// Homing failure condition: Limit switch not found during approach.
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if (approach && (rt_exec & EXEC_CYCLE_STOP)) { system_set_exec_alarm(EXEC_ALARM_HOMING_FAIL_APPROACH); }
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if (sys_rt_exec_alarm) {
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mc_reset(); // Stop motors, if they are running.
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protocol_execute_realtime();
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return;
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} else {
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// Pull-off motion complete. Disable CYCLE_STOP from executing.
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system_clear_exec_state_flag(EXEC_CYCLE_STOP);
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break;
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}
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}
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} while (STEP_MASK & axislock);
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st_reset(); // Immediately force kill steppers and reset step segment buffer.
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delay_ms(settings.homing_debounce_delay); // Delay to allow transient dynamics to dissipate.
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// Reverse direction and reset homing rate for locate cycle(s).
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approach = !approach;
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// After first cycle, homing enters locating phase. Shorten search to pull-off distance.
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if (approach) {
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max_travel = settings.homing_pulloff*HOMING_AXIS_LOCATE_SCALAR;
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homing_rate = settings.homing_feed_rate;
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} else {
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max_travel = settings.homing_pulloff;
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homing_rate = settings.homing_seek_rate;
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}
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} while (n_cycle-- > 0);
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// The active cycle axes should now be homed and machine limits have been located. By
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// default, Grbl defines machine space as all negative, as do most CNCs. Since limit switches
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// can be on either side of an axes, check and set axes machine zero appropriately. Also,
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// set up pull-off maneuver from axes limit switches that have been homed. This provides
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// some initial clearance off the switches and should also help prevent them from falsely
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// triggering when hard limits are enabled or when more than one axes shares a limit pin.
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int32_t set_axis_position;
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// Set machine positions for homed limit switches. Don't update non-homed axes.
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for (idx=0; idx<N_AXIS; idx++) {
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// NOTE: settings.max_travel[] is stored as a negative value.
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if (cycle_mask & bit(idx)) {
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#ifdef HOMING_FORCE_SET_ORIGIN
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set_axis_position = 0;
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#else
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if ( bit_istrue(settings.homing_dir_mask,bit(idx)) ) {
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set_axis_position = lround((settings.max_travel[idx]+settings.homing_pulloff)*settings.steps_per_mm[idx]);
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} else {
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set_axis_position = lround(-settings.homing_pulloff*settings.steps_per_mm[idx]);
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}
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#endif
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#ifdef COREXY
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if (idx==X_AXIS) {
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int32_t off_axis_position = system_convert_corexy_to_y_axis_steps(sys_position);
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sys_position[A_MOTOR] = set_axis_position + off_axis_position;
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sys_position[B_MOTOR] = set_axis_position - off_axis_position;
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} else if (idx==Y_AXIS) {
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int32_t off_axis_position = system_convert_corexy_to_x_axis_steps(sys_position);
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sys_position[A_MOTOR] = off_axis_position + set_axis_position;
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sys_position[B_MOTOR] = off_axis_position - set_axis_position;
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} else {
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sys_position[idx] = set_axis_position;
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}
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#else
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sys_position[idx] = set_axis_position;
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#endif
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}
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}
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sys.step_control = STEP_CONTROL_NORMAL_OP; // Return step control to normal operation.
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}
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// Performs a soft limit check. Called from mc_line() only. Assumes the machine has been homed,
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// the workspace volume is in all negative space, and the system is in normal operation.
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// NOTE: Used by jogging to limit travel within soft-limit volume.
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void limits_soft_check(float *target)
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{
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if (system_check_travel_limits(target)) {
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sys.soft_limit = true;
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// Force feed hold if cycle is active. All buffered blocks are guaranteed to be within
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// workspace volume so just come to a controlled stop so position is not lost. When complete
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// enter alarm mode.
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if (sys.state == STATE_CYCLE) {
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system_set_exec_state_flag(EXEC_FEED_HOLD);
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do {
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protocol_execute_realtime();
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if (sys.abort) { return; }
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} while ( sys.state != STATE_IDLE );
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}
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mc_reset(); // Issue system reset and ensure spindle and coolant are shutdown.
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system_set_exec_alarm(EXEC_ALARM_SOFT_LIMIT); // Indicate soft limit critical event
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protocol_execute_realtime(); // Execute to enter critical event loop and system abort
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return;
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}
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}
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