Re: [Emc-developers] Mesa Sigma5ABS module

[Curtis Dutton]

So I have made significant progress on the sigma5abs encoder front. I have
designed a manchester transiever in vhdl and integrated it into hostmot2
firmware as well as linuxcnc. I am close to having a fully functioning
driver. However there are a few mysteries remaining. This is the first
absolute encoder that I have had my hands on so I'm hoping others will know
more.


The encoders are 24 bit with 21 bits per turn so they track 8 turns worth
of counts. Part of the protocol has a 3 bit value that is a sort of turn
counter. It seems to only change if a complete turn is made. For example if
you rotate the encoder until the turn count changes, then reverse, the turn
value will not change until at least an entire rotation occurs. So
depending on the direction and partial reversing, each turn counter value
can occur at 3 different transition points.

This chart shows a mapping between the 24 bit count and possible "turn"
values.



2097152   7 0 1
4194304  0 1 2
6291456  1 2 3
8388608  2 3 4
10485760   3 4 5
12582912  4 5 6
14680064  5 6 7
16777216 (0)6 7 0



What is the technical term for this style of counter? I can see how it
could be used to determine the rollover point of the counter. What possible
ways should this be used?

Thanks,
   Curt

On Mon, Mar 30, 2020, 5:13 PM Curtis Dutton  wrote:

> Ok thanks. Once I get things working and know the register layout of the
> finished module I will get some advice as to a final proper address
> location.
>
> On Mon, Mar 30, 2020 at 5:01 PM Peter C. Wallace  wrote:
>
>> On Mon, 30 Mar 2020, Curtis Dutton wrote:
>>
>> > Date: Mon, 30 Mar 2020 16:33:13 -0400
>> > From: Curtis Dutton 
>> > Reply-To: EMC developers 
>> > To: EMC developers 
>> > Subject: [Emc-developers] Mesa Sigma5ABS module
>> >
>> > Hi all,
>> >
>> > I'm working out the design for the Yaskawa Sigma V absolute encoders.
>> >
>> > Within hostmot2-firmware,
>> >
>> > I've been studying the code and I'm not sure of the exact interface
>> between
>> > the mesa pci cards and linuxcnc.
>> >
>> > It seems that the pci card is mapping registers into memory and that
>> each
>> > module is reserving a register address so that the hostmot2 driver knows
>> > where to look for them to control them.
>> >
>> >
>> > In IDROMConst.vhd, I'm looking for register address space to use. But
>> I'm
>> > getting the feeling that it is all used up. Perhaps that is the reason
>> that
>> > pkuart chose to use the same address's as the uart module.
>> >
>> > The DPLLFreqLowAddr comments "note overlaps translate RAM" and "will
>> fix in
>> > the greate re-alignment"
>> >
>> > Does anyone know what the great re-alignment will be?
>> >
>> > Can anyone shed some light on the addressing scheme used with the mesa
>> > cards. Any other overview of how it works would be useful too.
>>
>> At one time there was only 32K of useable address space because the EPP
>> interfaced cards used the MSB of the address as an address autoinc flag.
>> Since
>> EPP interfaced cards are basically legacy devices at this point, newer
>> hm2
>> modules use addresses > 0x7FFF and currently B000,C000,D000,E000,F000 are
>> all
>> free.
>>
>> At some point, complile time allocation of module addresses might make
>> sense,
>> but that's a fairly large change so I think I'll wait until I run out of
>> address
>> space until I do that.
>>
>> Note, there's no harm in overlap as long as you dont expect to use the
>> overlapping modules in the same configuration
>>
>>
>> >
>> >
>> > Thanks,
>> >   Curt
>> >
>> > ___
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>> > Emc-developers@lists.sourceforge.net
>> > https://lists.sourceforge.net/lists/listinfo/emc-developers
>> >
>>
>> Peter Wallace
>> Mesa Electronics
>>
>>
>>
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>

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Re: [Emc-developers] startup anomaly on OLD LinuxCNC

[Jon Elson]

On 05/06/2020 11:26 AM, Sam Sokolik wrote:

I think the splash gcode sets the units to mm...  So if your program
doesn't change it back to inches you will get odd behavior...   (I think)

WOW, thank you!  Yes, that could completely explain the 
behavior.  I normally leave the machine in
inch mode at startup, so I don't have it in my boilerplate 
header. I think that could explain ALL the cases where I 
have had something odd happen.  (Anomalously slow motion was 
the other symptom I'd seen.)


Thanks,

Jon


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Re: [Emc-developers] startup anomaly on OLD LinuxCNC

[Gene Heskett]

On Wednesday 06 May 2020 12:26:15 Sam Sokolik wrote:

> I think the splash gcode sets the units to mm...  So if your program
> doesn't change it back to inches you will get odd behavior...   (I
> think)

That stuff has a place in the ini file, which may be overrode by the 
splash. But I've not noted that it has been.

> On Tue, May 5, 2020, 3:55 PM Jon Elson  wrote:
> > Yes, I KNOW, this is a REALLY old version, but just thought
> > I'd report it.
> >
> > I'm running LinuxCNC 2.5.4 on my Bridgeport mill.

How old is that code, Jon. :)

> > I just 
> > used it a couple days ago, everything worked
> > fine.  I started it up today, homed, and forgot to load the
> > toolpath, and pressed R with the LinuxCNC
> > toolpath still loaded.  I immediately noticed it was heading
> > for the wrong place and hit esc to abort it.
> > I then loaded the correct .ngc file, and when I pressed R,
> > it again headed toward (0,0).
> > I reloaded the toolpath several times, getting the same
> > response from that path and another old toolpath I tried.
> >
> > Finally, I exited LinuxCNC and restarted, homed, loaded the
> > toolpath and all was fine.
> > I believe I have experienced something like this behavior
> > twice before, and never was able to put my finger on what
> > was wrong.
> >
> > I am using the Axis GUI.
> >
> > Yes, someday I will update this system, but it does all I
> > need right now, I don't do any LinuxCNC development on it,
> > just cut metal.
> >
> > Thanks for any comments,
> >
> > Jon
> >
> >
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Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-developers] startup anomaly on OLD LinuxCNC

[Sam Sokolik]

I think the splash gcode sets the units to mm...  So if your program
doesn't change it back to inches you will get odd behavior...   (I think)


On Tue, May 5, 2020, 3:55 PM Jon Elson  wrote:

> Yes, I KNOW, this is a REALLY old version, but just thought
> I'd report it.
>
> I'm running LinuxCNC 2.5.4 on my Bridgeport mill.  I just
> used it a couple days ago, everything worked
> fine.  I started it up today, homed, and forgot to load the
> toolpath, and pressed R with the LinuxCNC
> toolpath still loaded.  I immediately noticed it was heading
> for the wrong place and hit esc to abort it.
> I then loaded the correct .ngc file, and when I pressed R,
> it again headed toward (0,0).
> I reloaded the toolpath several times, getting the same
> response from that path and another old toolpath I tried.
>
> Finally, I exited LinuxCNC and restarted, homed, loaded the
> toolpath and all was fine.
> I believe I have experienced something like this behavior
> twice before, and never was able to put my finger on what
> was wrong.
>
> I am using the Axis GUI.
>
> Yes, someday I will update this system, but it does all I
> need right now, I don't do any LinuxCNC development on it,
> just cut metal.
>
> Thanks for any comments,
>
> Jon
>
>
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