/** \brief run heater PID algorithm
\param h which heater we're running the loop for
\param type which temp sensor type this heater is attached to
\param current_temp the temperature that the associated temp sensor is reporting
\param target_temp the temperature we're trying to achieve
*/
void heater_tick(heater_t h, temp_type_t type, uint16_t current_temp, uint16_t target_temp) {
uint8_t pid_output;
#ifndef BANG_BANG
int16_t heater_p;
int16_t heater_d;
int16_t t_error = target_temp - current_temp;
#endif /* BANG_BANG */
if (h >= NUM_HEATERS)
return;
if (target_temp == 0) {
heater_set(h, 0);
return;
}
#ifndef BANG_BANG
heaters_runtime[h].temp_history[heaters_runtime[h].temp_history_pointer++] = current_temp;
heaters_runtime[h].temp_history_pointer &= (TH_COUNT - 1);
// PID stuff
// proportional
heater_p = t_error;
// integral
heaters_runtime[h].heater_i += t_error;
// prevent integrator wind-up
if (heaters_runtime[h].heater_i > heaters_pid[h].i_limit)
heaters_runtime[h].heater_i = heaters_pid[h].i_limit;
else if (heaters_runtime[h].heater_i < -heaters_pid[h].i_limit)
heaters_runtime[h].heater_i = -heaters_pid[h].i_limit;
// derivative
// note: D follows temp rather than error so there's no large derivative when the target changes
heater_d = heaters_runtime[h].temp_history[heaters_runtime[h].temp_history_pointer] - current_temp;
// combine factors
int32_t pid_output_intermed = (
(
(((int32_t) heater_p) * heaters_pid[h].p_factor) +
(((int32_t) heaters_runtime[h].heater_i) * heaters_pid[h].i_factor) +
(((int32_t) heater_d) * heaters_pid[h].d_factor)
) / PID_SCALE
);
// rebase and limit factors
if (pid_output_intermed > 255)
pid_output = 255;
else if (pid_output_intermed < 0)
pid_output = 0;
else
pid_output = pid_output_intermed & 0xFF;
#ifdef DEBUG
if (DEBUG_PID && (debug_flags & DEBUG_PID))
sersendf_P(PSTR("T{E:%d, P:%d * %ld = %ld / I:%d * %ld = %ld / D:%d * %ld = %ld # O: %ld = %u}\n"), t_error, heater_p, heaters_pid[h].p_factor, (int32_t) heater_p * heaters_pid[h].p_factor / PID_SCALE, heaters_runtime[h].heater_i, heaters_pid[h].i_factor, (int32_t) heaters_runtime[h].heater_i * heaters_pid[h].i_factor / PID_SCALE, heater_d, heaters_pid[h].d_factor, (int32_t) heater_d * heaters_pid[h].d_factor / PID_SCALE, pid_output_intermed, pid_output);
#endif
#else
if (current_temp >= target_temp)
pid_output = BANG_BANG_OFF;
else //BANG_BANG
pid_output = BANG_BANG_ON;
#endif
#ifdef HEATER_SANITY_CHECK
// check heater sanity
// implementation is a moving window with some slow-down to compensate for thermal mass
if (target_temp > (current_temp + (TEMP_HYSTERESIS*4))) {
// heating
if (current_temp > heaters_runtime[h].sane_temperature)
// hotter than sane- good since we're heating unless too hot
heaters_runtime[h].sane_temperature = current_temp;
else {
if (heaters_runtime[h].sanity_counter < 40)
heaters_runtime[h].sanity_counter++;
else {
heaters_runtime[h].sanity_counter = 0;
// ratchet up expected temp
heaters_runtime[h].sane_temperature++;
}
}
// limit to target, so if we overshoot by too much for too long an error is flagged
if (heaters_runtime[h].sane_temperature > target_temp)
heaters_runtime[h].sane_temperature = target_temp;
}
else if (target_temp < (current_temp - (TEMP_HYSTERESIS*4))) {
// cooling
if (current_temp < heaters_runtime[h].sane_temperature)
// cooler than sane- good since we're cooling
heaters_runtime[h].sane_temperature = current_temp;
else {
if (heaters_runtime[h].sanity_counter < 125)
heaters_runtime[h].sanity_counter++;
else {
heaters_runtime[h].sanity_counter = 0;
// ratchet down expected temp
heaters_runtime[h].sane_temperature--;
}
}
// if we're at or below 60 celsius, don't freak out if we can't drop any more.
if (current_temp <= 240)
heaters_runtime[h].sane_temperature = current_temp;
// limit to target, so if we don't cool down for too long an error is flagged
else if (heaters_runtime[h].sane_temperature < target_temp)
heaters_runtime[h].sane_temperature = target_temp;
}
// we're within HYSTERESIS of our target
else {
heaters_runtime[h].sane_temperature = current_temp;
heaters_runtime[h].sanity_counter = 0;
}
// compare where we're at to where we should be
if (labs((int16_t)(current_temp - heaters_runtime[h].sane_temperature)) > (TEMP_HYSTERESIS*4)) {
// no change, or change in wrong direction for a long time- heater is broken!
pid_output = 0;
sersendf_P(PSTR("!! heater %d or its temp sensor broken - temp is %d.%dC, target is %d.%dC, didn't reach %d.%dC in %d0 milliseconds\n"), h, current_temp >> 2, (current_temp & 3) * 25, target_temp >> 2, (target_temp & 3) * 25, heaters_runtime[h].sane_temperature >> 2, (heaters_runtime[h].sane_temperature & 3) * 25, heaters_runtime[h].sanity_counter);
}
void process_gcode_command() {
uint32_t backup_f;
// convert relative to absolute
if (next_target.option_all_relative) {
next_target.target.X += startpoint.X;
next_target.target.Y += startpoint.Y;
next_target.target.Z += startpoint.Z;
}
// E relative movement.
// Matches Sprinter's behaviour as of March 2012.
if (next_target.option_all_relative || next_target.option_e_relative)
next_target.target.e_relative = 1;
else
next_target.target.e_relative = 0;
// implement axis limits
#ifdef X_MIN
if (next_target.target.X < X_MIN * 1000.)
next_target.target.X = X_MIN * 1000.;
#endif
#ifdef X_MAX
if (next_target.target.X > X_MAX * 1000.)
next_target.target.X = X_MAX * 1000.;
#endif
#ifdef Y_MIN
if (next_target.target.Y < Y_MIN * 1000.)
next_target.target.Y = Y_MIN * 1000.;
#endif
#ifdef Y_MAX
if (next_target.target.Y > Y_MAX * 1000.)
next_target.target.Y = Y_MAX * 1000.;
#endif
#ifdef Z_MIN
if (next_target.target.Z < Z_MIN * 1000.)
next_target.target.Z = Z_MIN * 1000.;
#endif
#ifdef Z_MAX
if (next_target.target.Z > Z_MAX * 1000.)
next_target.target.Z = Z_MAX * 1000.;
#endif
// The GCode documentation was taken from http://reprap.org/wiki/Gcode .
if (next_target.seen_T) {
//? --- T: Select Tool ---
//?
//? Example: T1
//?
//? Select extruder number 1 to build with. Extruder numbering starts at 0.
next_tool = next_target.T;
}
if (next_target.seen_G) {
uint8_t axisSelected = 0;
switch (next_target.G) {
case 0:
//? G0: Rapid Linear Motion
//?
//? Example: G0 X12
//?
//? In this case move rapidly to X = 12 mm. In fact, the RepRap firmware uses exactly the same code for rapid as it uses for controlled moves (see G1 below), as - for the RepRap machine - this is just as efficient as not doing so. (The distinction comes from some old machine tools that used to move faster if the axes were not driven in a straight line. For them G0 allowed any movement in space to get to the destination as fast as possible.)
//?
backup_f = next_target.target.F;
next_target.target.F = MAXIMUM_FEEDRATE_X * 2L;
enqueue(&next_target.target);
next_target.target.F = backup_f;
break;
case 1:
//? --- G1: Linear Motion at Feed Rate ---
//?
//? Example: G1 X90.6 Y13.8 E22.4
//?
//? Go in a straight line from the current (X, Y) point to the point (90.6, 13.8), extruding material as the move happens from the current extruded length to a length of 22.4 mm.
//?
enqueue(&next_target.target);
break;
// G2 - Arc Clockwise
// unimplemented
// G3 - Arc Counter-clockwise
// unimplemented
case 4:
//? --- G4: Dwell ---
//?
//? Example: G4 P200
//?
//? In this case sit still doing nothing for 200 milliseconds. During delays the state of the machine (for example the temperatures of its extruders) will still be preserved and controlled.
//?
queue_wait();
// delay
if (next_target.seen_P) {
for (;next_target.P > 0;next_target.P--) {
clock();
delay_ms(1);
}
}
break;
case 20:
//? --- G20: Set Units to Inches ---
//?
//? Example: G20
//?
//? Units from now on are in inches.
//?
next_target.option_inches = 1;
break;
case 21:
//? --- G21: Set Units to Millimeters ---
//?
//? Example: G21
//?
//? Units from now on are in millimeters. (This is the RepRap default.)
//?
next_target.option_inches = 0;
break;
case 30:
//? --- G30: Go home via point ---
//?
//? Undocumented.
enqueue(&next_target.target);
// no break here, G30 is move and then go home
case 28:
//? --- G28: Home ---
//?
//? Example: G28
//?
//? This causes the RepRap machine to move back to its X, Y and Z zero endstops. It does so accelerating, so as to get there fast. But when it arrives it backs off by 1 mm in each direction slowly, then moves back slowly to the stop. This ensures more accurate positioning.
//?
//? If you add coordinates, then just the axes with coordinates specified will be zeroed. Thus
//?
//? G28 X0 Y72.3
//?
//? will zero the X and Y axes, but not Z. The actual coordinate values are ignored.
//?
queue_wait();
if (next_target.seen_X) {
#if defined X_MIN_PIN
home_x_negative();
#elif defined X_MAX_PIN
home_x_positive();
#endif
axisSelected = 1;
}
if (next_target.seen_Y) {
#if defined Y_MIN_PIN
home_y_negative();
#elif defined Y_MAX_PIN
home_y_positive();
#endif
axisSelected = 1;
}
if (next_target.seen_Z) {
#if defined Z_MAX_PIN
home_z_positive();
#elif defined Z_MIN_PIN
home_z_negative();
#endif
axisSelected = 1;
}
// there's no point in moving E, as E has no endstops
if (!axisSelected) {
home();
}
break;
case 90:
//? --- G90: Set to Absolute Positioning ---
//?
//? Example: G90
//?
//? All coordinates from now on are absolute relative to the origin
//? of the machine. This is the RepRap default.
//?
//? If you ever want to switch back and forth between relative and
//? absolute movement keep in mind, X, Y and Z follow the machine's
//? coordinate system while E doesn't change it's position in the
//? coordinate system on relative movements.
//?
// No wait_queue() needed.
next_target.option_all_relative = 0;
break;
case 91:
//? --- G91: Set to Relative Positioning ---
//?
//? Example: G91
//?
//? All coordinates from now on are relative to the last position.
//?
// No wait_queue() needed.
next_target.option_all_relative = 1;
break;
case 92:
//? --- G92: Set Position ---
//?
//? Example: G92 X10 E90
//?
//? Allows programming of absolute zero point, by reseting the current position to the values specified. This would set the machine's X coordinate to 10, and the extrude coordinate to 90. No physical motion will occur.
//?
queue_wait();
if (next_target.seen_X) {
startpoint.X = next_target.target.X;
axisSelected = 1;
}
if (next_target.seen_Y) {
startpoint.Y = next_target.target.Y;
axisSelected = 1;
}
if (next_target.seen_Z) {
startpoint.Z = next_target.target.Z;
axisSelected = 1;
}
if (next_target.seen_E) {
startpoint.E = next_target.target.E;
axisSelected = 1;
}
if (axisSelected == 0) {
startpoint.X = next_target.target.X =
startpoint.Y = next_target.target.Y =
startpoint.Z = next_target.target.Z =
startpoint.E = next_target.target.E = 0;
}
dda_new_startpoint();
break;
case 161:
//? --- G161: Home negative ---
//?
//? Find the minimum limit of the specified axes by searching for the limit switch.
//?
if (next_target.seen_X)
home_x_negative();
if (next_target.seen_Y)
home_y_negative();
if (next_target.seen_Z)
home_z_negative();
break;
case 162:
//? --- G162: Home positive ---
//?
//? Find the maximum limit of the specified axes by searching for the limit switch.
//?
if (next_target.seen_X)
home_x_positive();
if (next_target.seen_Y)
home_y_positive();
if (next_target.seen_Z)
home_z_positive();
break;
// unknown gcode: spit an error
default:
sersendf_P(PSTR("E: Bad G-code %d"), next_target.G);
// newline is sent from gcode_parse after we return
return;
}
}
else if (next_target.seen_M) {
uint8_t i;
switch (next_target.M) {
case 0:
//? --- M0: machine stop ---
//?
//? Example: M0
//?
//? http://linuxcnc.org/handbook/RS274NGC_3/RS274NGC_33a.html#1002379
//? Unimplemented, especially the restart after the stop. Fall trough to M2.
//?
case 2:
//? --- M2: program end ---
//?
//? Example: M2
//?
//? http://linuxcnc.org/handbook/RS274NGC_3/RS274NGC_33a.html#1002379
//?
queue_wait();
for (i = 0; i < NUM_HEATERS; i++)
temp_set(i, 0);
power_off();
break;
case 112:
//? --- M112: Emergency Stop ---
//?
//? Example: M112
//?
//? Any moves in progress are immediately terminated, then RepRap shuts down. All motors and heaters are turned off.
//? It can be started again by pressing the reset button on the master microcontroller. See also M0.
//?
timer_stop();
queue_flush();
power_off();
cli();
for (;;)
wd_reset();
break;
case 6:
//? --- M6: tool change ---
//?
//? Undocumented.
tool = next_tool;
break;
case 82:
//? --- M82 - Set E codes absolute ---
//?
//? This is the default and overrides G90/G91.
//? M82/M83 is not documented in the RepRap wiki, behaviour
//? was taken from Sprinter as of March 2012.
//?
//? While E does relative movements, it doesn't change its
//? position in the coordinate system. See also comment on G90.
//?
// No wait_queue() needed.
next_target.option_e_relative = 0;
break;
case 83:
//? --- M83 - Set E codes relative ---
//?
//? Counterpart to M82.
//?
// No wait_queue() needed.
next_target.option_e_relative = 1;
break;
// M84- stop idle hold
case 84:
stepper_disable();
x_disable();
y_disable();
z_disable();
e_disable();
break;
// M3/M101- extruder on
case 3:
case 101:
//? --- M101: extruder on ---
//?
//? Undocumented.
if (temp_achieved() == 0) {
enqueue(NULL);
}
#ifdef DC_EXTRUDER
heater_set(DC_EXTRUDER, DC_EXTRUDER_PWM);
#elif E_STARTSTOP_STEPS > 0
do {
// backup feedrate, move E very quickly then restore feedrate
backup_f = startpoint.F;
startpoint.F = MAXIMUM_FEEDRATE_E;
SpecialMoveE(E_STARTSTOP_STEPS, MAXIMUM_FEEDRATE_E);
startpoint.F = backup_f;
} while (0);
#endif
break;
// M102- extruder reverse
// M5/M103- extruder off
case 5:
case 103:
//? --- M103: extruder off ---
//?
//? Undocumented.
#ifdef DC_EXTRUDER
heater_set(DC_EXTRUDER, 0);
#elif E_STARTSTOP_STEPS > 0
do {
// backup feedrate, move E very quickly then restore feedrate
backup_f = startpoint.F;
startpoint.F = MAXIMUM_FEEDRATE_E;
SpecialMoveE(-E_STARTSTOP_STEPS, MAXIMUM_FEEDRATE_E);
startpoint.F = backup_f;
} while (0);
#endif
break;
case 104:
//? --- M104: Set Extruder Temperature (Fast) ---
//?
//? Example: M104 S190
//?
//? Set the temperature of the current extruder to 190<sup>o</sup>C and return control to the host immediately (''i.e.'' before that temperature has been reached by the extruder). See also M116.
//? Teacup supports an optional P parameter as a sensor index to address (eg M104 P1 S100 will set the bed temperature rather than the extruder temperature).
//?
if ( ! next_target.seen_S)
break;
if ( ! next_target.seen_P)
next_target.P = HEATER_EXTRUDER;
temp_set(next_target.P, next_target.S);
if (next_target.S)
power_on();
break;
case 105:
//? --- M105: Get Extruder Temperature ---
//?
//? Example: M105
//?
//? Request the temperature of the current extruder and the build base in degrees Celsius. The temperatures are returned to the host computer. For example, the line sent to the host in response to this command looks like
//?
//? <tt>ok T:201 B:117</tt>
//?
//? Teacup supports an optional P parameter as a sensor index to address.
//?
#ifdef ENFORCE_ORDER
queue_wait();
#endif
if ( ! next_target.seen_P)
next_target.P = TEMP_SENSOR_none;
temp_print(next_target.P);
break;
case 7:
case 106:
//? --- M106: Set Fan Speed ---
//?
//? Example: M106 S120
//?
//? Control the cooling fan (if any).
//?
#ifdef ENFORCE_ORDER
// wait for all moves to complete
queue_wait();
#endif
#ifdef HEATER_FAN
if ( ! next_target.seen_S)
break;
temp_set(HEATER_FAN, next_target.S);
if (next_target.S)
power_on();
#endif
break;
case 110:
//? --- M110: Set Current Line Number ---
//?
//? Example: N123 M110
//?
//? Set the current line number to 123. Thus the expected next line after this command will be 124.
//? This is a no-op in Teacup.
//?
break;
#ifdef DEBUG
case 111:
//? --- M111: Set Debug Level ---
//?
//? Example: M111 S6
//?
//? Set the level of debugging information transmitted back to the host to level 6. The level is the OR of three bits:
//?
//? <Pre>
//? #define DEBUG_PID 1
//? #define DEBUG_DDA 2
//? #define DEBUG_POSITION 4
//? </pre>
//?
//? This command is only available in DEBUG builds of Teacup.
if ( ! next_target.seen_S)
break;
debug_flags = next_target.S;
break;
#endif
// M113- extruder PWM
case 114:
//? --- M114: Get Current Position ---
//?
//? Example: M114
//?
//? This causes the RepRap machine to report its current X, Y, Z and E coordinates to the host.
//?
//? For example, the machine returns a string such as:
//?
//? <tt>ok C: X:0.00 Y:0.00 Z:0.00 E:0.00</tt>
//?
#ifdef ENFORCE_ORDER
// wait for all moves to complete
queue_wait();
#endif
update_current_position();
sersendf_P(PSTR("X:%lq,Y:%lq,Z:%lq,E:%lq,F:%lu"),
current_position.X, current_position.Y,
current_position.Z, current_position.E,
current_position.F);
#ifdef DEBUG
if (DEBUG_POSITION && (debug_flags & DEBUG_POSITION)) {
sersendf_P(PSTR(",c:%lu}\nEndpoint: X:%ld,Y:%ld,Z:%ld,E:%ld,F:%lu,c:%lu}"),
movebuffer[mb_tail].c, movebuffer[mb_tail].endpoint.X,
movebuffer[mb_tail].endpoint.Y, movebuffer[mb_tail].endpoint.Z,
movebuffer[mb_tail].endpoint.E, movebuffer[mb_tail].endpoint.F,
#ifdef ACCELERATION_REPRAP
movebuffer[mb_tail].end_c
#else
movebuffer[mb_tail].c
#endif
);
print_queue();
}
#endif /* DEBUG */
// newline is sent from gcode_parse after we return
break;
case 115:
//? --- M115: Get Firmware Version and Capabilities ---
//?
//? Example: M115
//?
//? Request the Firmware Version and Capabilities of the current microcontroller
//? The details are returned to the host computer as key:value pairs separated by spaces and terminated with a linefeed.
//?
//? sample data from firmware:
//? FIRMWARE_NAME:Teacup FIRMWARE_URL:http://github.com/triffid/Teacup_Firmware/ PROTOCOL_VERSION:1.0 MACHINE_TYPE:Mendel EXTRUDER_COUNT:1 TEMP_SENSOR_COUNT:1 HEATER_COUNT:1
//?
sersendf_P(PSTR("FIRMWARE_NAME:Teacup FIRMWARE_URL:http://github.com/triffid/Teacup_Firmware/ PROTOCOL_VERSION:1.0 MACHINE_TYPE:Mendel EXTRUDER_COUNT:%d TEMP_SENSOR_COUNT:%d HEATER_COUNT:%d"), 1, NUM_TEMP_SENSORS, NUM_HEATERS);
// newline is sent from gcode_parse after we return
break;
case 116:
//? --- M116: Wait ---
//?
//? Example: M116
//?
//? Wait for temperatures and other slowly-changing variables to arrive at their set values.
enqueue(NULL);
break;
case 130:
//? --- M130: heater P factor ---
//? Undocumented.
if ( ! next_target.seen_P)
next_target.P = HEATER_EXTRUDER;
if (next_target.seen_S)
pid_set_p(next_target.P, next_target.S);
break;
case 131:
//? --- M131: heater I factor ---
//? Undocumented.
if ( ! next_target.seen_P)
next_target.P = HEATER_EXTRUDER;
if (next_target.seen_S)
pid_set_i(next_target.P, next_target.S);
break;
case 132:
//? --- M132: heater D factor ---
//? Undocumented.
if ( ! next_target.seen_P)
next_target.P = HEATER_EXTRUDER;
if (next_target.seen_S)
pid_set_d(next_target.P, next_target.S);
break;
case 133:
//? --- M133: heater I limit ---
//? Undocumented.
if ( ! next_target.seen_P)
next_target.P = HEATER_EXTRUDER;
if (next_target.seen_S)
pid_set_i_limit(next_target.P, next_target.S);
break;
case 134:
//? --- M134: save PID settings to eeprom ---
//? Undocumented.
heater_save_settings();
break;
case 135:
//? --- M135: set heater output ---
//? Undocumented.
if ( ! next_target.seen_P)
next_target.P = HEATER_EXTRUDER;
if (next_target.seen_S) {
heater_set(next_target.P, next_target.S);
power_on();
}
break;
#ifdef DEBUG
case 136:
//? --- M136: PRINT PID settings to host ---
//? Undocumented.
//? This comand is only available in DEBUG builds.
if ( ! next_target.seen_P)
next_target.P = HEATER_EXTRUDER;
heater_print(next_target.P);
break;
#endif
case 140:
//? --- M140: Set heated bed temperature ---
//? Undocumented.
#ifdef HEATER_BED
if ( ! next_target.seen_S)
break;
temp_set(HEATER_BED, next_target.S);
if (next_target.S)
power_on();
#endif
break;
case 190:
//? --- M190: Power On ---
//? Undocumented.
//? This one is pointless in Teacup. Implemented to calm the RepRap gurus.
//?
power_on();
stepper_enable();
x_enable();
y_enable();
z_enable();
e_enable();
break;
case 191:
//? --- M191: Power Off ---
//? Undocumented.
//? Same as M2. RepRap obviously prefers to invent new numbers instead of looking into standards.
#ifdef ENFORCE_ORDER
// wait for all moves to complete
queue_wait();
#endif
power_off();
break;
case 200:
//? --- M200: report endstop status ---
//? Report the current status of the endstops configured in the firmware to the host.
power_on();
#if defined(X_MIN_PIN)
sersendf_P(PSTR("x_min:%d "), x_min());
#endif
#if defined(X_MAX_PIN)
sersendf_P(PSTR("x_max:%d "), x_max());
#endif
#if defined(Y_MIN_PIN)
sersendf_P(PSTR("y_min:%d "), y_min());
#endif
#if defined(Y_MAX_PIN)
sersendf_P(PSTR("y_max:%d "), y_max());
#endif
#if defined(Z_MIN_PIN)
sersendf_P(PSTR("z_min:%d "), z_min());
#endif
#if defined(Z_MAX_PIN)
sersendf_P(PSTR("z_max:%d "), z_max());
#endif
#if !(defined(X_MIN_PIN) || defined(X_MAX_PIN) || defined(Y_MIN_PIN) || defined(Y_MAX_PIN) || defined(Z_MIN_PIN) || defined(Z_MAX_PIN))
sersendf_P(PSTR("no endstops defined"));
#endif
break;
#ifdef DEBUG
case 240:
//? --- M240: echo off ---
//? Disable echo.
//? This command is only available in DEBUG builds.
debug_flags &= ~DEBUG_ECHO;
serial_writestr_P(PSTR("Echo off"));
// newline is sent from gcode_parse after we return
break;
case 241:
//? --- M241: echo on ---
//? Enable echo.
//? This command is only available in DEBUG builds.
debug_flags |= DEBUG_ECHO;
serial_writestr_P(PSTR("Echo on"));
// newline is sent from gcode_parse after we return
break;
#endif /* DEBUG */
// unknown mcode: spit an error
default:
sersendf_P(PSTR("E: Bad M-code %d"), next_target.M);
// newline is sent from gcode_parse after we return
} // switch (next_target.M)
} // else if (next_target.seen_M)
} // process_gcode_command()