// 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.
void limitpin_check(void)
{
static uint8_t oldlimit;
uint8_t newlimit;
if(!limitintison) return;
newlimit = limits_get_state();
if(newlimit == oldlimit) return;
oldlimit = newlimit;
// 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() == 0) return;
#endif
mc_reset(); // Initiate system kill.
if(newlimit & 0x8)
system_set_exec_alarm_flag((EXEC_ALARM_STEPPER_FAIL|EXEC_CRITICAL_EVENT)); // Indicate hard limit critical event
else
system_set_exec_alarm_flag((EXEC_ALARM_HARD_LIMIT|EXEC_CRITICAL_EVENT)); // Indicate hard limit critical event
}
}
}
// Perform homing cycle to locate and set machine zero. Only '$H' executes this command.
// NOTE: There should be no motions in the buffer and Grbl must be in an idle state before
// executing the homing cycle. This prevents incorrect buffered plans after homing.
void mc_homing_cycle()
{
// Check and abort homing cycle, if hard limits are already enabled. Helps prevent problems
// with machines with limits wired on both ends of travel to one limit pin.
// TODO: Move the pin-specific LIMIT_PIN call to limits.c as a function.
#ifdef LIMITS_TWO_SWITCHES_ON_AXES
if (limits_get_state()) {
mc_reset(); // Issue system reset and ensure spindle and coolant are shutdown.
bit_true_atomic(sys_rt_exec_alarm, (EXEC_ALARM_HARD_LIMIT|EXEC_CRITICAL_EVENT));
return;
}
#endif
limits_disable(); // Disable hard limits pin change register for cycle duration
// -------------------------------------------------------------------------------------
// Perform homing routine. NOTE: Special motion case. Only system reset works.
// Search to engage all axes limit switches at faster homing seek rate.
limits_go_home(HOMING_CYCLE_0); // Homing cycle 0
#ifdef HOMING_CYCLE_1
limits_go_home(HOMING_CYCLE_1); // Homing cycle 1
#endif
#ifdef HOMING_CYCLE_2
limits_go_home(HOMING_CYCLE_2); // Homing cycle 2
#endif
#ifdef HOMING_CYCLE_3
limits_go_home(HOMING_CYCLE_3); // Homing cycle 3
#endif
#ifdef HOMING_CYCLE_4
limits_go_home(HOMING_CYCLE_4); // Homing cycle 4
#endif
#ifdef HOMING_CYCLE_5
limits_go_home(HOMING_CYCLE_5); // Homing cycle 5
#endif
protocol_execute_realtime(); // Check for reset and set system abort.
if (sys.abort) { return; } // Did not complete. Alarm state set by mc_alarm.
// Homing cycle complete! Setup system for normal operation.
// -------------------------------------------------------------------------------------
// Gcode parser position was circumvented by the limits_go_home() routine, so sync position now.
gc_sync_position();
// If hard limits feature enabled, re-enable hard limits pin change register after homing cycle.
limits_init();
}
// Perform homing cycle to locate and set machine zero. Only '$H' executes this command.
// NOTE: There should be no motions in the buffer and Grbl must be in an idle state before
// executing the homing cycle. This prevents incorrect buffered plans after homing.
void mc_homing_cycle(uint8_t cycle_mask)
{
// Check and abort homing cycle, if hard limits are already enabled. Helps prevent problems
// with machines with limits wired on both ends of travel to one limit pin.
// TODO: Move the pin-specific LIMIT_PIN call to limits.c as a function.
#ifdef LIMITS_TWO_SWITCHES_ON_AXES
if (limits_get_state()) {
mc_reset(); // Issue system reset and ensure spindle and coolant are shutdown.
system_set_exec_alarm(EXEC_ALARM_HARD_LIMIT);
return;
}
#endif
limits_disable(); // Disable hard limits pin change register for cycle duration
// -------------------------------------------------------------------------------------
// Perform homing routine. NOTE: Special motion case. Only system reset works.
#ifdef HOMING_SINGLE_AXIS_COMMANDS
if (cycle_mask) { limits_go_home(cycle_mask); } // Perform homing cycle based on mask.
else
#endif
{
// Search to engage all axes limit switches at faster homing seek rate.
limits_go_home(HOMING_CYCLE_0); // Homing cycle 0
#ifdef HOMING_CYCLE_1
limits_go_home(HOMING_CYCLE_1); // Homing cycle 1
#endif
#ifdef HOMING_CYCLE_2
limits_go_home(HOMING_CYCLE_2); // Homing cycle 2
#endif
}
protocol_execute_realtime(); // Check for reset and set system abort.
if (sys.abort) { return; } // Did not complete. Alarm state set by mc_alarm.
// Homing cycle complete! Setup system for normal operation.
// -------------------------------------------------------------------------------------
// Sync gcode parser and planner positions to homed position.
gc_sync_position();
plan_sync_position();
// If hard limits feature enabled, re-enable hard limits pin change register after homing cycle.
limits_init();
}
// 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
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++;
sys.position[idx] = 0;
// 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;
plan_sync_position(); // Sync planner position to current machine position.
// Perform homing cycle. Planner buffer should be empty, as required to initiate the homing cycle.
#ifdef USE_LINE_NUMBERS
plan_buffer_line(target, homing_rate, false, false, HOMING_CYCLE_LINE_NUMBER); // Bypass mc_line(). Directly plan homing motion.
#else
plan_buffer_line(target, homing_rate, false, false); // Bypass mc_line(). Directly plan homing motion.
#endif
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)) { axislock &= ~(step_pin[idx]); }
}
}
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)) {
// Homing failure: Limit switches are still engaged after pull-off motion
if ( (sys_rt_exec_state & (EXEC_SAFETY_DOOR | EXEC_RESET)) || // Safety door or reset issued
(!approach && (limits_get_state() & cycle_mask)) || // Limit switch still engaged after pull-off motion
( approach && (sys_rt_exec_state & EXEC_CYCLE_STOP)) ) { // Limit switch not found during approach.
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.
plan_reset(); // Reset planner buffer to zero planner current position and to clear previous motions.
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.
#ifdef COREXY
int32_t off_axis_position = 0;
#endif
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) {
off_axis_position = (sys.position[B_MOTOR] - sys.position[A_MOTOR])/2;
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) {
off_axis_position = (sys.position[A_MOTOR] + sys.position[B_MOTOR])/2;
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
}
}
plan_sync_position(); // Sync planner position to homed machine position.
// sys.state = STATE_HOMING; // Ensure system state set as homing before returning.
}
// Prints real-time data. This function grabs a real-time snapshot of the stepper subprogram
// and the actual location of the CNC machine. Users may change the following function to their
// specific needs, but the desired real-time data report must be as short as possible. This is
// requires as it minimizes the computational overhead and allows grbl to keep running smoothly,
// especially during g-code programs with fast, short line segments and high frequency reports (5-20Hz).
void report_realtime_status()
{
// **Under construction** Bare-bones status report. Provides real-time machine position relative to
// the system power on location (0,0,0) and work coordinate position (G54 and G92 applied). Eventually
// to be added are distance to go on block, processed block id, and feed rate. Also a settings bitmask
// for a user to select the desired real-time data.
uint8_t idx;
int32_t current_position[N_AXIS]; // Copy current state of the system position variable
memcpy(current_position,sys.position,sizeof(sys.position));
float print_position[N_AXIS];
// Report current machine state
switch (sys.state) {
case STATE_IDLE: printPgmString(PSTR("<Idle")); break;
case STATE_MOTION_CANCEL: // Report run state.
case STATE_CYCLE: printPgmString(PSTR("<Run")); break;
case STATE_HOLD: printPgmString(PSTR("<Hold")); break;
case STATE_HOMING: printPgmString(PSTR("<Home")); break;
case STATE_ALARM: printPgmString(PSTR("<Alarm")); break;
case STATE_CHECK_MODE: printPgmString(PSTR("<Check")); break;
case STATE_SAFETY_DOOR: printPgmString(PSTR("<Door")); break;
}
// If reporting a position, convert the current step count (current_position) to millimeters.
if (bit_istrue(settings.status_report_mask,(BITFLAG_RT_STATUS_MACHINE_POSITION | BITFLAG_RT_STATUS_WORK_POSITION))) {
system_convert_array_steps_to_mpos(print_position,current_position);
}
// Report machine position
if (bit_istrue(settings.status_report_mask,BITFLAG_RT_STATUS_MACHINE_POSITION)) {
printPgmString(PSTR(",MPos:"));
for (idx=0; idx< N_AXIS; idx++) {
printFloat_CoordValue(print_position[idx]);
if (idx < (N_AXIS-1)) { printPgmString(PSTR(",")); }
}
}
// Report work position
if (bit_istrue(settings.status_report_mask,BITFLAG_RT_STATUS_WORK_POSITION)) {
printPgmString(PSTR(",WPos:"));
for (idx=0; idx< N_AXIS; idx++) {
// Apply work coordinate offsets and tool length offset to current position.
print_position[idx] -= gc_state.coord_system[idx]+gc_state.coord_offset[idx];
if (idx == TOOL_LENGTH_OFFSET_AXIS) { print_position[idx] -= gc_state.tool_length_offset; }
printFloat_CoordValue(print_position[idx]);
if (idx < (N_AXIS-1)) { printPgmString(PSTR(",")); }
}
}
// Returns the number of active blocks are in the planner buffer.
if (bit_istrue(settings.status_report_mask,BITFLAG_RT_STATUS_PLANNER_BUFFER)) {
printPgmString(PSTR(",Buf:"));
print_uint8_base10(plan_get_block_buffer_count());
}
// Report serial read buffer status
if (bit_istrue(settings.status_report_mask,BITFLAG_RT_STATUS_SERIAL_RX)) {
printPgmString(PSTR(",RX:"));
print_uint8_base10(serial_get_rx_buffer_count());
}
#ifdef USE_LINE_NUMBERS
// Report current line number
printPgmString(PSTR(",Ln:"));
int32_t ln=0;
plan_block_t * pb = plan_get_current_block();
if(pb != NULL) {
ln = pb->line_number;
}
printInteger(ln);
#endif
#ifdef REPORT_REALTIME_RATE
// Report realtime rate
printPgmString(PSTR(",F:"));
printFloat_RateValue(st_get_realtime_rate());
#endif
if (bit_istrue(settings.status_report_mask,BITFLAG_RT_STATUS_LIMIT_PINS)) {
printPgmString(PSTR(",Lim:"));
print_unsigned_int8(limits_get_state(),2,N_AXIS);
}
#ifdef REPORT_CONTROL_PIN_STATE
printPgmString(PSTR(",Ctl:"));
print_uint8_base2(CONTROL_PIN & CONTROL_MASK);
#endif
printPgmString(PSTR(">\r\n"));
}
