maybe bugmenot has a login
I could register twice ;)
but then you'd have twice as much support work to do ;)
yeah, but he can start flamewars
and argue with himself
It would be nice - Most of the questions I have no clue. ;)
sounds like fun
No it wouldn't - Yes it would
I have cought fenn lurking from time to time ;)
skunkworks: how is the FET bridge cooking?
cool.... I have a use for a 3 1/2 bridge version for driving a 3ph servo
micrcontroller side is running, but I need a power stage
LawrenceG: I don't know if the circuit would be condusive to 3 phase. I would think you would need to control both the high and low fets separatly.
A-L-P-H-A_ is now known as A-L-P-H-A
The circuit I have uses a ir2111 which has only 1 input - high activates the high fet - low activates the low fet
skunkworks: that should be ok as I am generating 3 pwm phase signals
getting all the fets onto a heatsink might be an interesting layout challenge
maybe 3" al pipe with flats milled on it!
adding 2 more fets and 2 more diodes and a 2111 could be interesting
got to take the dog for a walkabout... bbl
Give me a sec - I can upload the eagle schematic to my website.. it should only be used for connection - not values :)
gotta run, but I'll take a look later
the docs say: It is OK to use M3 or M4 if the spindle speed is set to zero.
emc actually says: Spindle speed needs to be non-zero in order to enable.
If speed is 0 we have no way of telling that you really wanted clockwise.
and in fact with this simulated spindle, mdi s0 / m3 / s100 does send the spindle to 100rpm after giving an error
but if it was in a program it would abort because of this message
"It is OK to use M3 or M4 if the spindle speed is set to zero. If this is done (or if the speed override switch is enabled and set to zero), the spindle will not start turning. If, later, the spindle speed is set above zero (or the override switch is turned up), the spindle will start turning."
besides the error, the implementation seems to match the documentation
I remember adding that for a reason
now I remember.. spindle inc/dec
if you kept decreasing from some spindle speed it would go negative at some point
not sure what the behaviour needs to be there
skunkworks: thankyou... it looks like your picture if of a virginal drive.... have you let any smoke out yet?
run it as a spinle through emc2 - 60+ volts - few amps. No smoke yet.
alex_joni: this code is only called from the interpreter, it's unrelated to spindle speed increase/decrease through the GUI
cool... my servos are 100v about 4 amp.... might get away with minimal heat sinks
want to run these :) http://www.electronicsam.com/images/KandT/DSC_0242.JPG
yea ha... that should warm em up
LawrenceG: there is no current limiting in the circuit yet as you can see. They may be ver 2 depending on how things work.
jepler: that may be
can't really recall
understood.... I have been playing with another servo amp (linear mode current source) for small brushed motors that is working quite well...
LawrenceG: page 20 has a 3 phase circuit using an ir2110 (2 input) http://www.irf.com/technical-info/appnotes/an-978.pdf
LawrenceG: cool. how are you controlling it? right from emc - or through a uP
(I am trying to make it a simple as possible - emc as the pid loop)
it uses a dspic and gets a quadrature phase drive from emc. The servo code is very similar to the hal module,,,, just cut down to 1 axis.
extra points for using quadrature, by the way
that keeps things simple.... no encoder interface needed in the pc
Jepler: Agreed. Then you can output steps at period - correct?
yea I like quadrature drive.... more noise immunity, twice as fast as step dir as it can move on each phase change
My kiss plan is emc2->pwmgen->h-bridge->servo->encoder->emc2.....
pwmgen is a hal module
jepler: some parts use only the speed to set direction too, if I remember it correctly
pretty much what jepler and cradek have done with thier toys
yea... I didnt want to encumber the pc with having to keep up with all the i/o required for encoder interface
If you have the ability. I don't right now. I/o is cheap for me :)
the off pc servo loop is a little harder to tune, but once setup it doesnt need much maintenance
jepler: sorry.. can't remember more than that.. try taking it out of emccanon.cc
LawrenceG: very similar to the gecko servo drives? except your using quadrature instead of step and dir?
alex_joni: you mean that some machines without spindle speed control would turn on the spindle with 'S0 M3'?
alex_joni: those machines could be fixed with an alteration to their .hal
probably so.. but there might be some other issue I can't remember :(
skunkworks: yes... my output stage is limited to about 6 amps peak
skunkworks: your output stage would just about tie onto my controller without many changes
actually, motion.spindle-on, -forward, and -backward all go to false if S0 is commanded, even if M3 or M4 is also active
jepler: at least I got something right
well.. I have no issues if you take it out
if something breaks we'll fix it :)
skunkworks: I use a dir and pwm to control the power i/o, but that could be changed to 2 complementary pwm signals
either way - probably easier to change in code rather than adding logic.
[19:18:22] <alex_joni> http://cvs.linuxcnc.org/cgi-bin/cvsweb.cgi/emc2/src/emc/task/emccanon.cc.diff?r1=1.29;r2=1.30
skunkworks: yes... a quick reflash of the micro
not all micros have complementary pwm
jepler: just the reverse of that diff :)
older avrs don't
alex_joni: yeah, I found that diff too
I spent the last 10 minutes trying to remember why I added that
dspic has 6 pwm which can be setup as 3ph complementary drive
"aditional checking for spindle clock/counterclockwise opperation. if speed is 0, we have no way of telling what direction is used." -- change message from 1.30
yeah, saw that.. but doesn't ring much of a bell
jepler: you know there are a few things missing from AXIS :)
jepler: it looks like it still works as it should
only thing I'm seeing is if you use spindle forward, then decrease the speed to 0 you won't be able to go back
interestingly, you made a change to ioControl.cc at the same time which fixed the behavior of the spindle-on and spindle-forward signals when speed is 0
need to stop, and hit spindle forward again
yep that's true
guess that's a feature :)
maybe we should forbid EMC_SPINDLE_DECREASE from going to 0?
* alex_joni tries it out
check 'er in
in it comes
at times like this I realize how important cvs commit logs are :D
yep looks good
I wonder if an opto driving an transister would be enough to set spindle speed
using pwmgen I mean
this stuff that's going on now, is it for 2.1 or 2.1+n?
2.1 for now
it hasn't been branched yet
only after branching will it go to feature freeze
wasn't there feature-lock a while back?
oh, I see
only for 2.0
which is one of the reasons why 2.1 is taking so much :)
2.0 basicly works great
so, not a real pressure for 2.1
2.1 is in pretty good shape, and it has a lot of great features. I think we should freeze for 2.1 sooner rather than later, so that our users get these features.
alex_joni: how many amps?
yeah, I think so too
but they can always run cvs head!
* Lerneaen_Hydra ducks for cover
Lerneaen_Hydra: that's bad
* Lerneaen_Hydra 's sheild protects very well
skunkworks: up to 3-4
small motor :)
Give it a try. Do you have any darlington transisters? I would think an opto would run a darlington just fine.
need to look :)
I have some nice IGBT's
300A @ 600V .. do those count ?
there you go.
a safety margin is always nice :p
lol.. driving a 12V 1A motor
you never know what could happen
well.. if it's too small I can find bigger ones :)
remember our welding PSU's go up to 650A or so :D
yeah, might be worth looking into
that would be insane, having to have welding PSU's to drive the *servo*
probably way too low voltage
only up to 70-80V DC
ssh! don't make it not come true
alex_joni: just don't run the darlingtons into saturation. Don't want any of that slow switching :) (kidding)
hmm.. here's a thought
how about using a H-bridge and an ir2111
Good luck so far :) Don't knock it
Your just jelous
you're that is
but I had better transistors :P
RDSon = 17mOhm
35A @ 100 deg C
I think I have a bunch of them :)
so why not use them?
what voltage are they? like 60v?
my bridge used 2 of those, and 2 x IRF4905
_no_ ir2111 :P
a tiny bit more expensive, but way easier to get running
not enough voltage.
55V Vdss for both
I was running at 12V
so it was enough for me
You keep saying "way easier" but I have not had any problems yet :)
like I said.. either you got lucky, or I got bad luck
I have not pushed them yet - but I have run around 60v at 2 amps through it so far.
I have my mica insulators so I can add the heatsinks now also.
is it really mica?
So I can see if I can vaporize pcb traces :) I have some 2oz copper clad coming.
TOZAI IS-3MP 407 MICA INSULATOR FOR TO-3P / TO-247
haven't seen mica in a while :)
only synthetic stuff
old stock I assume
price was right
I got a few bags with samples from the trade last week :)
off to bed now
good night all
Night alex. Dream about spindle control
* alex_joni wakes up in the middle of the night screaming and full of sweat
Oh - thats normal. don't worry about it
ok, I'll try not to worry too much