kiwigrant

Looking at the diagram I just posted – HLFB is the High Level Feedback signal coming from the Clearpath motors.

I my intention is to use this signal during a homing routine to sense the gantry hitting the end stops without the need of having to wire in limit switches.

Its been more hassle than what it worth to be frank – but Im weird that way.

I also had an exclusive AND gate chip laying around, and if you send the same signal to the inputs of XAND you end up with a NOT. You can omit those if you can configure your “Enable” function on the steppingstones drivers to true high to true low.

Remember the joy of this hobby is going down the rabbit hole and learning…

Yes

I use logic shifters to shit 3.3 volts to 5 vs.

I used the ones from adafruit although there are plenty of alternatives from amazon.

I soldered headers into he TinyG board and created another board which i connected using a ribbon cable. using vero board.

I did begin design a better board in Eagle CAD but haven’t got back to that project for some time.

Let me see if I can print a diagram of how i did it…

I needed to pass, pulse and direction plus enable.. which works great. one element you do want to becareful of is that you match the pulse frequency does not execute the maximum pulse frequency of the stepper driver.

Hope this helps.

Grant

You know you have have you Z Polarity set to reverse.

[3ma] m3 map to axis 2 [0=X,1=Y,2=Z…]
[3sa] m3 step angle 1.800 deg
[3tr] m3 travel per revolution 8.0000 mm
[3mi] m3 microsteps 8 [1,2,4,8]
[3po] m3 polarity 1 [0=normal,1=reverse]

Not sure if this is a requirement of your machines geometry.

sending a -z move should send the tool down during normal operation.

Now I have observed some anomalous behavior with the G38.2 command and the direction of travel.

Reading the Touch plate widget code when you issue a G38.2 z-20 F75 command. The probe should go down if only if you are above MCS or G28.3 z-20 ie > z-20. If you are lower then G28.3 MCS say at MCS -30 when you issue a G38.2 z-20 F75 the probe will go up.

So it seems that the probing direction is set by your relative position to MCS and z-20. I believe this is the correct behaviour in the TinyG.

There are 2 ways to work around this.
1. Zero out MCS to zero as you begin the probing operation/. This isnt a good idea really because itll screw up other operation that are dependent on MCS. but at a pinch this will get your probing operation to work as desired in the right direction.

2. Set the G38.2 command with a z value that is appropriate for where you are currently at using the MCS… ie MCS current Z position – z20. This is not how the code is currently set up to do.

3. Set the Z value to a -ve number that you are unlikely to be near. This is also not preferred because this could drive the machine to crash if not equipped with limit switches and if the probe contact fails. This is not how the code is currently set up to do.

Right now I have the Supertouch plate widget code open as Im adding functions to allow us to probe +ve and -Ve on X & Y. Ill see if I can add the preferred behaviour I described in option 2.

@cmcgrath5035

I installed..
[fb] firmware build 449.01
[fv] firmware version 0.97

It did not change the behavior of the probing routine to recognize $ST for probing and still assume probes are NO…

I was hoping it would detect state change in either direction. but only operates going low-> high ie Normally Open behavior

Time to make a logic inverter… sadly

I have a switched probe that is that is “NC”.

G38.2 seems to ignore $ST

I read in earlier post (2014ish) that during that G38.2 looks for a state change and is therefore not affected by $ST.

This would be ideal as I intend to use both a touch off plate “NO” as well as my sensor probe “NC”

So far my G38.2 command is responding as if it is not looking for a state change rather it is behaving as if it only supports transitions from the NO state.

The motors should be de-energised to move them by hand.

you can move them by hand in order to zero out the machine.

Once the machine has been zeroed you shouldn’t move it by hand again because the board doesnt see the change in position. i.e. typically after zero you move the machine by jogging.

you can move the machine by hand again if you change the tool and you need to re-zero again.