mux4 for axis select??

OT-CNC
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15 Mar 2018 17:53 #107383 by OT-CNC

mux4 for axis select?? was created by OT-CNC

I'm working on a jog pendant/ MPG handwheel. I have the mux4 component working for jog increment select based on MPG pendant
examples:
linuxcnc.org/docs/html/examples/mpg.html
Question is, is there a way to implement mux4 for axis select? Based on the mux4 manual it only works with input values:
linuxcnc.org/docs/ja/html/man/man9/mux4.9.html

I'm a bit short on wiring and I'm looking for a workaround to do axis select A,X,Y,Z with 2 inputs.

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cmorley
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15 Mar 2018 18:03 #107384 by cmorley

Replied by cmorley on topic mux4 for axis select??

mux_generic can have bit output pins.

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OT-CNC
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15 Mar 2018 18:11 #107386 by OT-CNC

Replied by OT-CNC on topic mux4 for axis select??

I just looked at the doc:
linuxcnc.org/docs/html/man/man9/mux_generic.9.html

Is there a good hal example out there that uses the 2 inputs that I can look at to adapt?

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cmorley
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15 Mar 2018 19:16 - 15 Mar 2018 19:17 #107389 by cmorley

Replied by cmorley on topic mux4 for axis select??

Sorry I lead you astray... looks like mux_generic wouldnt do what you wish.
Seems you actually need to de-multiplex signals.

so 2 bit inputs control 4 bit outputs.
you may need to compile a custom component or use classicladder.
Some one else may have a smarter answer for you yet...

Chris M

Last edit: 15 Mar 2018 19:17 by cmorley.

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cmorley
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15 Mar 2018 19:43 - 15 Mar 2018 19:44 #107391 by cmorley

Replied by cmorley on topic mux4 for axis select??

I think this would do it:

component dmux2 "Select one of four output values";
pin in bit sel0;
pin in bit sel1;

pin out bit out0;
pin out bit out1;
pin out bit out2;
pin out bit out3;
function _;
license "GPL";
;;
FUNCTION(_) {
    if(sel0) {
        if(sel1) {

                    out0 =0;
                    out1 =0;
                    out2 =0;
                    out3 =1;
        }else{
                    out0 =0;
                    out1 =1;
                    out2 =0;
                    out3 =0;
        }
    }else {
          if(sel1) {
                    out0 =0;
                    out1 =0;
                    out2 =1;
                    out3 =0;
          }else{
                    out0 =1;
                    out1 =0;
                    out2 =0;
                    out3 =0;
          }
    }
}

Last edit: 15 Mar 2018 19:44 by cmorley. Reason: change name to dmux2

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Todd Zuercher
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15 Mar 2018 19:45 #107392 by Todd Zuercher

Replied by Todd Zuercher on topic mux4 for axis select??

I think you can do this with the hal logic component.
linuxcnc.org/docs/html/man/man9/logic.9.html
I'll have to think on it a bit to be able to give you an example how to use it in your hal file.

Till then, maybe Andy (I think he wrote this little gem) will chime in with instructions.

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Todd Zuercher
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15 Mar 2018 20:29 #107395 by Todd Zuercher

Replied by Todd Zuercher on topic mux4 for axis select??

Never mind logic doesn't work.

It might not be as elegant as writing a component, but you could do it by simply using 4 and2s connected to the your two input pins and their inverses.

X=00
Y=01
Z=10
A=11
If you were using parallel ports pin 9 and 10 as your inputs it would look something like this.

loadrt and2 count=4
addf and2.0 servo-thread
addf and2.1 servo-thread
addf and2.2 servo-thread
addf and2.3 servo-thread

net input1-not  <= parport.1.pin-9-in-not => and2.0.in0
net input2-not  <= parport.1.pin-10-in-not => and2.0.in1
net mpg-x <= and2.0.out => axis.0.jog-enable

net input1-not => and2.1.in0
net input2 <= parport.1.pin-10-in => and2.1.in1
net mpg-y <= and2.1.out => axis.0.jog-enable

net input1 <= parport.1.pin-9-in-not => and2.2.in0
net input2-not => and2.2.in1
net mpg-z <= and2.2.out => axis.0.jog-enable

net input1 => and2.3.in0
net input2 => and2.3.in1
net mpg-z <= and2.3.out => axis.0.jog-enable

The following user(s) said Thank You: OT-CNC

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OT-CNC
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15 Mar 2018 20:35 #107396 by OT-CNC

Replied by OT-CNC on topic mux4 for axis select??

I appreciate the leads. I will try the last example and see if I can adapt it.

Thank you!

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andypugh
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15 Mar 2018 22:59 #107403 by andypugh

Replied by andypugh on topic mux4 for axis select??

This could also be done with multiswitch
But I am not sure it is worth the bother, because you would have to turn the input bits into a number with weighted_sum and then, because select8 takes a signed-32 input (for no good reason) you would need to convert to S32 with conv_s32_u32

An alternative would be to use 4 x binary mux4 components (from mux_generic with each having three zero inputs and one true input.

Or 4 x lut5

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rodw
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16 Mar 2018 00:00 #107405 by rodw

Replied by rodw on topic mux4 for axis select??

I don't think you need a special component. I have used a Mux8 and Select8 for axis select. I only have 3 axes but my pendant had a 6 position switch. The trick is to convert the type to use it in the select8.
This is basically identical to the way I select the scale using a Mux4.

loadrt mux8 count=1
loadrt select8 count=1
addf mux8.0                   servo-thread
addf select8.0                servo-thread

#Axis Select (0=off, 1=x, 2=z, 3=y, na, 5=6, 6=4, 7=5) 
setp mux8.0.in0 0
setp mux8.0.in1 1
setp mux8.0.in2 2
setp mux8.0.in3 3
setp mux8.0.in4 4
setp mux8.0.in5 5
setp mux8.0.in6 6
setp mux8.0.in7 7
net mux8-sel0 <= hm2_7i76e.0.7i76.0.0.input-23
net mux8-sel1 <= hm2_7i76e.0.7i76.0.0.input-24
net mux8-sel2 <= hm2_7i76e.0.7i76.0.0.input-25
net mux8-sel0 => mux8.0.sel0
net mux8-sel1 => mux8.0.sel1
net mux8-sel2 => mux8.0.sel2

net mux-float conv-float-s32.1.in <= mux8.0.out

net mux-s32   <= conv-float-s32.1.out
net mux-s32   => select8.0.sel
net axis-select-x <= select8.0.out1
net axis-select-y <= select8.0.out3
net axis-select-z <= select8.0.out2
net axis-select-4 <= select8.0.out6
net axis-select-5 <= select8.0.out7
net axis-select-6 <= select8.0.out5

net axis-select-x => axis.x.jog-enable
net axis-select-y => axis.y.jog-enable
net axis-select-z => axis.z.jog-enable

I think I copied everything I used.

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