Bed Auto Leveling feature

Check the Readme for instruction how to enable and configure the feature

README.md

@@ -48,6 +48,7 @@ Features:
 *   Configurable serial port to support connection of wireless adaptors.
 *   Automatic operation of extruder/cold-end cooling fans based on nozzle temperature
 *   RC Servo Support, specify angle or duration for continuous rotation servos.
+*   Bed Auto Leveling.
 
 The default baudrate is 250000. This baudrate has less jitter and hence errors than the usual 115200 baud, but is less supported by drivers and host-environments.
 
@@ -142,6 +143,8 @@ Implemented G Codes:
 *  G10 - retract filament according to settings of M207
 *  G11 - retract recover filament according to settings of M208
 *  G28 - Home all Axis
+*  G29 - Detailed Z-Probe, probes the bed at 3 points.  You must de at the home position for this to work correctly.
+*  G30 - Single Z Probe, probes bed at current XY location.
 *  G90 - Use Absolute Coordinates
 *  G91 - Use Relative Coordinates
 *  G92 - Set current position to cordinates given
@@ -210,6 +213,8 @@ M Codes
 *  M303 - PID relay autotune S<temperature> sets the target temperature. (default target temperature = 150C)
 *  M304 - Set bed PID parameters P I and D
 *  M400 - Finish all moves
+*  M401 - Lower z-probe if present
+*  M402 - Raise z-probe if present
 *  M500 - stores paramters in EEPROM
 *  M501 - reads parameters from EEPROM (if you need reset them after you changed them temporarily).
 *  M502 - reverts to the default "factory settings".  You still need to store them in EEPROM afterwards if you want to.
@@ -249,6 +254,69 @@ If all goes well the firmware is uploading
 
 That's ok.  Enjoy Silky Smooth Printing.
 
+===============================================
+Instructions for configuring Bed Auto Leveling
+===============================================
+Uncomment the "ENABLE_AUTO_BED_LEVELING" define (commented by default)
+
+You will probably need a swivel Z-MIN endstop in the extruder. A rc servo do a great job.
+Check the system working here: http://www.youtube.com/watch?v=3IKMeOYz-1Q (Enable English subtitles)
+Teasing ;-) video: http://www.youtube.com/watch?v=x8eqSQNAyro
+
+In order to get the servo working, you need to enable:
+
+* \#define NUM_SERVOS 1 // Servo index starts with 0 for M280 command
+
+* \#define SERVO_ENDSTOPS {-1, -1, 0} // Servo index for X, Y, Z. Disable with -1
+
+* \#define SERVO_ENDSTOP_ANGLES {0,0, 0,0, 165,60} // X,Y,Z Axis Extend and Retract angles
+
+
+The first define tells firmware how many servos you have.
+The second tells what axis this servo will be attached to. In the example above, we have a servo in Z axis.
+The third one tells the angle in 2 situations: Probing (165º) and resting (60º). Check this with command M280 P0 S{angle}
+
+Next you need to define the Z endstop (probe) offset from hotend.
+My preferred method:
+
+* a) Make a small mark in the bed with a marker/felt-tip pen.
+* b) Place the hotend tip as *exactly* as possible on the mark, touching the bed. Raise the hotend 0.1mm (a regular paper thickness) and zero all axis (G92 X0 Y0 Z0);
+* d) Raise the hotend 10mm (or more) for probe clearance, lower the Z probe (Z-Endstop) with M401 and place it just on that mark by moving X, Y and Z;
+* e) Lower the Z in 0.1mm steps, with the probe always touching the mark (it may be necessary to adjust X and Y as well) until you hear the "click" meaning the mechanical endstop was trigged. You can confirm with M119;
+* f) Now you have the probe in the same place as your hotend tip was before. Perform a M114 and write down the values, for example: X:24.3 Y:-31.4 Z:5.1;
+* g) You can raise the z probe with M402 command;
+* h) Fill the defines bellow multiplying the values by "-1" (just change the signal)
+
+
+* \#define X_PROBE_OFFSET_FROM_EXTRUDER -24.3
+* \#define Y_PROBE_OFFSET_FROM_EXTRUDER 31.4
+* \#define Z_PROBE_OFFSET_FROM_EXTRUDER -5.1
+
+
+The following options define the probing positions. These are good starting values.
+I recommend to keep a better clearance from borders in the first run and then make the probes as close as possible to borders:
+
+* \#define LEFT_PROBE_BED_POSITION 30
+* \#define RIGHT_PROBE_BED_POSITION 140
+* \#define BACK_PROBE_BED_POSITION 140
+* \#define FRONT_PROBE_BED_POSITION 30
+
+A few more options:
+
+* \#define XY_TRAVEL_SPEED 6000
+
+X and Y axis travel speed between probes, in mm/min.
+Bear in mind that really fast moves may render step skipping. 6000 mm/min (100mm/s) is a good value.
+
+* \#define Z_RAISE_BEFORE_PROBING 10
+* \#define Z_RAISE_BETWEEN_PROBINGS 10
+
+The Z axis is lifted when traveling to the first probe point by Z_RAISE_BEFORE_PROBING value
+and then lifted when traveling from first to second and second to third point by Z_RAISE_BETWEEN_PROBINGS.
+All values are in mm as usual. 
+
+That's it.. enjoy never having to calibrate your Z endstop neither leveling your bed by hand anymore ;-)
+