PnCConf -- Inverting Step Gen / Dir Gen signals

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Amedee
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09 Feb 2016 20:54 - 09 Feb 2016 20:57 #69883 by Amedee

PnCConf -- Inverting Step Gen / Dir Gen signals was created by Amedee

I am new to LinuxCNC, and I am trying to configure all the electronics step by step.

I have a 6i25/7i76 combo connected to Leadshine DM556 drivers in 'differential mode' (Step +/- to Pulse +/-)

It all works well (using the 'Test/Tune Axis' tool), but I was trying to understand if I was triggering on the right edge (step pulse and space have the same duration on these drivers, so either way would probably work).

I started changing the 'Inv' checkbox for Step Gen / Dir Gen; but I could not see any difference -- also measuring the voltage on the board did not show any difference.
When I looked at 'hm2_5i25.0.gpio.000.invert_output'/'hm2_5i25.0.gpio.001.invert_output'' with Hal Meter they were always 'FALSE' regardless of the 'inv' checkbox status

Now when entering the 'Test/Tune Axis' tool, I could see on the console

<stdin>:40: setp requires 2 arguments, 4 given

A quick look at the source showed that we were missing a '\n':

--- tests.py.orig	2016-02-09 21:26:03.385859170 +0100
+++ tests.py	2016-02-09 21:42:46.501248302 +0100
@@ -676,7 +676,7 @@
                 self.scale = get_value(w[axis + "stepscale"]) * 1
             stepinvertlist = self.a.stepgen_invert_pins(step_sig)
             for i in stepinvertlist:
-                halrun.write("setp    "+i+".invert_output true")
+                halrun.write("setp    "+i+".invert_output true\n")
             halrun.write("setp %s.step_type 0 \n"% (self.step_signalname))
             halrun.write("setp %s.control-type 1 \n"% (self.step_signalname))
             halrun.write("setp %s.position-scale %f \n"% (self.step_signalname,self.scale))

With this quick fix I now have the correct flag in Hal Meter, but I still can't see a real difference in my tests (nor in the board voltages)
Am I doing something wrong here, or is there a better way to test?

(Running LinuxCNC 2.7.3 / Linux 3.16.0-9-rtai-686-pae)

Edit: don't know what's happening, but my posts always end up in the wrong section -- maybe because I navigate in another browser tab... Anyway, if this could be moved in the PnCConf section...

Last edit: 09 Feb 2016 20:57 by Amedee. Reason: Wrong section

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PCW
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09 Feb 2016 21:39 #69884 by PCW

Replied by PCW on topic PnCConf -- Inverting Step Gen / Dir Gen signals

Its important to get the step polarity correct because the direction change setup and
hold times are measured from the leading edge of the step pulse

( though if you set these much longer than the step pulse and dont violate minimum step and idle times,
the step pulse polarity doesn't matter )

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cmorley
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10 Feb 2016 01:40 #69898 by cmorley

Replied by cmorley on topic PnCConf -- Inverting Step Gen / Dir Gen signals

I appreciate the bug report especially with bug fixes included!

I will push this one too.
Chris M

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Amedee
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10 Feb 2016 20:30 #69959 by Amedee

Replied by Amedee on topic PnCConf -- Inverting Step Gen / Dir Gen signals

Thank you Chris!

However, I am still a bit confused, and I tested again this evening, re-measuring the voltages on the board.

I do see a change now when I invert, but they invert the wrong signal!

That is: Inverting 'Step Gen' will invert the Dir signal, and the opposite!

When you invert 'Step Gen', you generate 'setp hm2_5i25.0.gpio.000.invert_output true'
When you invert 'Dir Gen', you generate 'setp hm2_5i25.0.gpio.001.invert_output true'

It makes sense at first, but when I look at the 7i76 manual (Page 10) it seems that Dir is mapped on GPIO 0 and Step on GPIO 1

Don't we have the GPIO pin mapping wrong?

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cmorley
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11 Feb 2016 06:39 #69976 by cmorley

Replied by cmorley on topic PnCConf -- Inverting Step Gen / Dir Gen signals

I will have to check on this later in the week

Chris M

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Amedee
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11 Feb 2016 14:47 #69993 by Amedee

Replied by Amedee on topic PnCConf -- Inverting Step Gen / Dir Gen signals

Thank you

FYI, here is what dmesg says:

[ 5094.308716] hm2: loading Mesa HostMot2 driver version 0.15
[ 5094.330362] hm2_pci: loading Mesa AnyIO HostMot2 driver version 0.7
[ 5094.330756] ACPI: PCI Interrupt Link [APC2] enabled at IRQ 17
[ 5094.330777] hm2_pci: discovered 5i25 at 0000:03:00.0
[ 5094.331046] hm2/hm2_5i25.0: Smart Serial Firmware Version 43
[ 5094.388117] hm2/hm2_5i25.0: 34 I/O Pins used:
[ 5094.388127] hm2/hm2_5i25.0:     IO Pin 000 (P3-01): StepGen #0, pin Direction (Output)
[ 5094.388130] hm2/hm2_5i25.0:     IO Pin 001 (P3-14): StepGen #0, pin Step (Output)
[ 5094.388133] hm2/hm2_5i25.0:     IO Pin 002 (P3-02): StepGen #1, pin Direction (Output)
[ 5094.388136] hm2/hm2_5i25.0:     IO Pin 003 (P3-15): StepGen #1, pin Step (Output)
[ 5094.388139] hm2/hm2_5i25.0:     IO Pin 004 (P3-03): StepGen #2, pin Direction (Output)
[ 5094.388142] hm2/hm2_5i25.0:     IO Pin 005 (P3-16): StepGen #2, pin Step (Output)
[ 5094.388144] hm2/hm2_5i25.0:     IO Pin 006 (P3-04): StepGen #3, pin Direction (Output)
[ 5094.388147] hm2/hm2_5i25.0:     IO Pin 007 (P3-17): StepGen #3, pin Step (Output)
[ 5094.388150] hm2/hm2_5i25.0:     IO Pin 008 (P3-05): StepGen #4, pin Direction (Output)
[ 5094.388153] hm2/hm2_5i25.0:     IO Pin 009 (P3-06): StepGen #4, pin Step (Output)

This confirms that Dir is on GPIO pin 0 and Step on pin 1

An easy fix could be to swap STEPA/STEPB in private_data.py where they are 'assigned' to the board:

    424     ['5i25-Internal Data', '5i25', '7i76x2 -With One 7i76', '5i25', 'hm2_pci', 1,3, 0,0, 0,3, 0,0, 5,2, 1,2, 0,0,0,0,0,0,0,0, 1, 34, 33, 200, [3, 2],
    425         # TAB 3
    426         [S.STEPA,0],[S.STEPB,0],[S.STEPA,1],[S.STEPB,1],[S.STEPA,2],[S.STEPB,2],[S.STEPA,3],[S.STEPB,3],[S.STEPA,4],[S.STEPB,4],
    427         [S.SS7I76M0,0],[S.RXDATA0,0],[S.TXDATA1,0],[S.RXDATA1,0],[S.ENCI,0],[S.ENCB,0],[S.ENCA,0],
    428         [S.NUSED,0],[S.NUSED,0],[S.NUSED,0],[S.NUSED,0],[S.NUSED,0],[S.NUSED,0],[S.NUSED,0],

But that might look a bit strange as it would show 'B' before 'A' in the UI:

We can't just rename the pins ans say 'Dir Gen - A' / 'Step Gen - B', as other part of the code rely on the fact that STEPA is the step gen...

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cmorley
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14 Feb 2016 23:59 #70136 by cmorley

Replied by cmorley on topic PnCConf -- Inverting Step Gen / Dir Gen signals

I did in fact just swap the names in the firmware array.
I also took the chance to change the 7i76e firmware - I'm pretty sure it's the same.
Thanks again.

Chris M

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Amedee
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15 Feb 2016 08:16 #70153 by Amedee

Replied by Amedee on topic PnCConf -- Inverting Step Gen / Dir Gen signals

Thank you!

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PnCConf -- Inverting Step Gen / Dir Gen signals

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