Mesh bed leveling without M557

[Piet]

Dear users,

I noticed there is a possibility to create a mesh.g file and I'm wondering if i can use it to do the following. (I'm not totally sure how to use it so please enlighten me)

I have some hysteresis in my Z-probe. This means that if I run the G29 command and automatically probe all the predefined points, the value starts to shift to a point that the mesh is unusable. Normally before probing I measure the analog value of the probe and set a new threshold by adding a value to that measured value. Is there a way I can set a new threshold to trigger before every probe move in the mesh.g. I already have this code set up for regular bed leveling but I'm assuming I can't use the G30 command to do mesh bed leveling. Is this correct?

This is the code i already use:
probe.g

if !exists(param.X) || !exists(param.Y)														;if parameter X and Y are given
	echo "Make sure parameter X and Y are given (C and S optional). Aborting probe move."	;notify user
	
G1 X{param.X} Y{param.Y} Z{sensors.probes[0].diveHeight} F6000								;move to given X and Y coordinates and predefined diveheight
M400																						;wait for moves to finish

M291 R"Waiting for extruder." P" " S1
M116 P0 S2																					;wait for extruder to reach temperature

M568 P0 A0																					;turn the extruder heater off (interference changes sensor reading)

G4 S1																						;wait 1 second

M98 P"preprobe.g"																			;call macro to determine triggervalue and see if it is okay to proceed probing
M292

M291 R"Probing." P" " S1

if global.proceedProbe = true																;if its okay to proceed probing
	if exists(param.C)																		;if parameter C is given
		if exists(param.S)																	;if parameter S is given
			G30 X{param.X} Y{param.Y} P{param.C} S{param.S} Z-9999							;probe move
		else																				;otherwise
			G30 X{param.X} Y{param.Y} P{param.C} Z-9999										;probe move
	elif exists(param.S)																	;if parameter S is given
		G30 X{param.X} Y{param.Y} S{param.S} Z-9999											;probe move
	else																					;otherwise
		G30 X{param.X} Y{param.Y} Z-9999													;probe move
		
elif (global.proceedProbe = false)															;if it isnt okay to proceed probing
	echo "Aborting probe move"																;notify user

M292

M568 P0 A1																					;set the extruder heater to standby

preprobe.g

if !exists(global.proceedProbe)																										;if variable doesnt exist yet
	global proceedProbe = false																										;initialize variable
	
if exists(global.triggerVal)																										;if a triggervalue has been defined
	if sensors.probes[0].value[0] <= 922 && sensors.probes[0].value[0] >= 200														;if the sensorvalue is within acceptable range
		var measuredVal = {sensors.probes[0].value[0]}																				;measure the sensor value
		G31 P{var.measuredVal + global.triggerVal}																					;set the triggervalue to the measured value + the triggervalue
		;echo "Measured sensor value is", {var.measuredVal}, ". Triggervalue has been set to", {sensors.probes[0].threshold}, "."	;notify user
		set global.proceedProbe = true																								;set variable so probing can proceed
	
	else																															;otherwise
		echo "Measured sensor voltage is out of range at ", {(var.measuredVal * 5)/1024}, "V."										;notify user
		set global.proceedProbe = false																								;set variable so probing wont proceed
		
else																																;otherwise
	echo "The variable triggerVal has not been declared in the config.g file (default = 100)"										;notify user
	set global.proceedProbe = false																									;set variable so probing wont proceed
	

So instead of using the G30 command to probe i use M98 P"probe.g".

[T3P3Tony]

@piet if you cant change the way your probe works to not have the analogue hysteresis then you could manually create the mesh by carrying out the "G30" probes you want to, using G30 S-1:

G30 S-1 ; Probe the bed at the current XY position. When the probe is triggered, do not adjust the Z coordinate, just report the machine height at which the probe was triggered.

You would need to format the outputs in the same manner as heightmap.csv, potentially you could do this with a macro that stepper through the points you want and echoed it to a file using the ">>" construct.

[Piet]

@t3p3tony Smart! I don't have a heightmap saved, do you by any chance have an example so i can see how it's formatted?

[T3P3Tony]

@piet

here is an example

RepRapFirmware height map file v2 generated at 2021-04-28 22:58
xmin,xmax,ymin,ymax,radius,xspacing,yspacing,xnum,ynum
5.00,290.00,10.00,190.00,-1.00,15.00,15.00,20,13
  0.088,  0.103,  0.097,  0.082,  0.103,  0.097,  0.088,  0.060,  0.049,  0.049,  0.049,  0.082,  0.090,  0.103,  0.114,  0.123,  0.133,  0.140,  0.139,  0.135
  0.043,  0.058,  0.035,  0.037,  0.058,  0.059,  0.042,  0.021,  0.040,  0.037,  0.044,  0.051,  0.045,  0.076,  0.089,  0.100,  0.109,  0.116,  0.116,  0.110
  0.024,  0.040,  0.018,  0.019,  0.043,  0.037,  0.002,  0.001, -0.004, -0.002,  0.000,  0.026,  0.039,  0.052,  0.040,  0.075,  0.088,  0.089,  0.091,  0.087
  0.013,  0.017, -0.002,  0.027,  0.023,  0.013,  0.013, -0.017,  0.005,  0.002,  0.005,  0.014,  0.023,  0.034,  0.031,  0.057,  0.070,  0.074,  0.073,  0.067
  0.002,  0.008, -0.012,  0.017,  0.012, -0.017,  0.002,  0.001, -0.001, -0.007, -0.001,  0.003, -0.017,  0.024,  0.041,  0.047,  0.058,  0.061,  0.062,  0.055
 -0.003,  0.004,  0.005, -0.022,  0.002, -0.006, -0.010, -0.014, -0.013, -0.014, -0.012, -0.008,  0.002,  0.013,  0.030,  0.036,  0.046,  0.049,  0.048,  0.042
 -0.009, -0.003,  0.001, -0.003, -0.003, -0.013, -0.018, -0.022, -0.025, -0.024, -0.021, -0.018, -0.006,  0.003,  0.019,  0.027,  0.037,  0.039,  0.036,  0.030
 -0.006, -0.001, -0.004, -0.004, -0.008, -0.017, -0.021, -0.026, -0.030, -0.031, -0.028, -0.022, -0.013, -0.001,  0.012,  0.020,  0.029,  0.033,  0.030,  0.023
 -0.005, -0.006, -0.007, -0.004, -0.007, -0.018, -0.023, -0.027, -0.030, -0.033, -0.031, -0.025, -0.014, -0.004,  0.011,  0.020,  0.029,  0.031,  0.027,  0.022
  0.001,  0.003, -0.000,  0.000, -0.005, -0.014, -0.020, -0.026, -0.031, -0.033, -0.032, -0.024, -0.018, -0.005,  0.004,  0.020,  0.027,  0.030,  0.027,  0.022
  0.005,  0.007,  0.004,  0.004,  0.001, -0.007, -0.016, -0.021, -0.026, -0.026, -0.027, -0.021, -0.015, -0.002,  0.010,  0.020,  0.029,  0.033,  0.029,  0.026
  0.022,  0.026,  0.019,  0.018,  0.014,  0.008,  0.001, -0.006, -0.013, -0.014, -0.016, -0.008,  0.001,  0.013,  0.026,  0.033,  0.039,  0.041,  0.039,  0.035
  0.043,  0.044,  0.035,  0.035,  0.019,  0.020,  0.013,  0.007,  0.002, -0.015,  0.000,  0.003,  0.013,  0.022,  0.035,  0.042,  0.028,  0.052,  0.049,  0.046

[Piet]

For future reference, this works.
The probe file can be adjusted to allow for different types of probing.

if !exists(param.X) || !exists(param.Y)														;if parameter X and Y are given
	echo "Make sure parameter X and Y are given (C and S optional). Aborting probe move."	;notify user
	
G1 X{param.X} Y{param.Y} Z{sensors.probes[0].diveHeight} F6000								;move to given X and Y coordinates and predefined diveheight
M400																						;wait for moves to finish

M98 P"waitForHeaters.g" H01

M568 P0 A0																					;turn the extruder heater off (interference changes sensor reading)

G4 S1																						;wait 1 second

M98 P"preprobe.g"																			;call macro to determine triggervalue and see if it is okay to proceed probing

;M291 R"Probing." P" " S1

if global.proceedProbe = true																;if its okay to proceed probing
	if exists(param.C)																		;if parameter C is given
		if exists(param.S)																	;if parameter S is given
			G30 X{param.X} Y{param.Y} P{param.C} S{param.S} Z-9999							;probe move
		else																				;otherwise
			G30 X{param.X} Y{param.Y} P{param.C} Z-9999										;probe move
	elif exists(param.S)																	;if parameter S is given
		G30 X{param.X} Y{param.Y} S{param.S} Z-9999											;probe move
	else																					;otherwise
		G30 X{param.X} Y{param.Y} Z-9999													;probe move
		
elif (global.proceedProbe = false)															;if it isnt okay to proceed probing
	echo "Aborting probe move"																;notify user

;M292

M568 P0 A1																					;set the extruder heater to standby

if global.bedLeveled == 0	
	G32

M98 P"probe.g" X525 Y250

echo >"heightmap.csv" "Height map file generated at", state.time
echo >>"heightmap.csv" "xmin,xmax,ymin,ymax,radius,xspacing,yspacing,xnum,ynum"
echo >>"heightmap.csv" global.xMin,",",global.xMax,",",global.yMin,",",global.yMax, ", -1 ,",global.xSpacing,",",global.ySpacing,",",global.xNum,",",global.yNum
var y = global.yMin
var i = 0

G90

while var.i < global.yNum
	var x = global.xMin
	var j = 0
	while var.j < global.xNum
		M98 P"probe.g" X{var.x} Y{var.y} S-1
		M400
	
		if var.j == 0
			set global.meshLine = sensors.probes[0].lastStopHeight - sensors.probes[0].triggerHeight
		else 
			set global.meshLine = global.meshLine ^ "," ^ sensors.probes[0].lastStopHeight - sensors.probes[0].triggerHeight
		
		set var.x = var.x + global.xSpacing
		set var.j = var.j + 1
	
	echo >>"heightmap.csv" global.meshLine
	set var.y = var.y + global.ySpacing
	set var.i = var.i + 1