Re: unlurking

From Ted Robbins rtr@...

I am excited about your pproject as I am sure that others are as well. I
have a couple of comments at this stage in your design. It seems that you
are trying to make a stand alone unit probably fed from a pc. Would you
shorten design time and agony by using software rether than an eeprom to
hold the paramaters. You are probably going to end up remaining connected
to a pc anyway.

Your noise control techniques are always worth while and optical couplers
are worth using. If you stay connected, you will still need a seperate
source of power for the drivers, so you probably won't get away with a wall
wart.

As a tech nerd I like solder ball jumpers, but the machinists among us
might be better served by dip switches. Don't cost much and the function
of each switch can sometimes be screened right on the board. A fancier way
would be to put in a buffer reached by software. Might be more problem
than a simple dip switch.

A low cost microstepper would be a blessing for us all.


----------

> From: bobd@...
> To: CAD_CAM_EDM_DRO@onelist.com
> Subject: [CAD_CAM_EDM_DRO] unlurking
> Date: Saturday, June 26, 1999 6:07 AM
>
> From: "bobd@..." <bobd@...>
>
> Hi,
> I have been lurking here for a couple of months and feel that I should
> contribute. My name is Bob Dring and I do electronic design for a job and
> metalwork for a hobby. I have taken on a project for a friend to build a

'V

> groover' for PCBs. (My friend is a PCB manufacturer.) The Mechanical part
> was already done by someone else, it has stepper motors (200oz/in) linear
> bearings and ballscrews.
> For my part of the project I am designing the motor drivers, power

supply,

> etc. I hope to finish the first PCB layout for the driver in the next few
> days. The spec of the driver is overkill for this application but I

intend

> to use the same design for my own uses. The spec is 2 phase microstepping
> bipolar chopper drive of up to 80V @ 8Amps for driving one motor. I have
> put a fast micro in the design and because of this I can give it new and
> novel features, I am taking the opportunity to ask the group for advice

on

> what features would be desirable. I have made a list of the ones I am
> currently thinking of implementing but I would like comments and ideas.
>
> 1. Optoisolated inputs (step, direction, lowpower1, shutdown)
> 2. Optoisolated outputs (fault, lowpower2)
> 3. Takes DB25 pin cable (printer port style)
> 4. Pass through to another DB25 to daisy chain the next motor driver(s)
> 5. A jumper matrix (ball of solder type) on the PCB allowing any DB25 pin
> to be connected to the any driver input, output, ground.
> 6. A signal that allows automatic power reduction when all drivers have
> stopped (lowpower2).
> 7. Motor parameter setup up by RS232 port. (max phase current, lowpower
> phase current, low power delay time, etc)
> 8. Signal polarity setup by RS232 port (step, direction, lowpower1,
> shutdown, fault etc)
> 9. EEPROM to store parameters.
> 10. LEDs to show signals (clockwise, step, fault etc)
> 11. Motor connection and motor power via un pluggable terminal block

style

> connector.
> 12. Logic power 12Vac plug pack (wall wart).
> 13. Motor drive short circuit protection.
> 14. Fits in a snazzy aluminium extrusion.
>
> I will be doing a similar module for limit switch detection and spindle
> control.
>
> Before going further I should mention what stage I am up to.
>
> I have prototyped one phase of the motor driver on strip board and
> controlled it from a DAC driven from the micro. I have only run it at 60V
> at 4 Amps at the moment because the circuit becomes unstable at higher
> currents because stripboard is unsuitable for this type of circuit (at
> least I think that it is the reason!) No firmware has been written at

this

> stage (except the code to drive the 12 DAC that sets the max phase
> current). Hope to have some PCBs in a week.
>
> I know that many of you are probably saying to yourselves that this

project

> is going to cost a lot of money and I have to agree that it certainly

isn't

> a low budget design but in my defense I can only say The PCBs are being
> made for me at no cost and I can have as many prototype iterations as
> needed without financial penalty and so I am taking the opportunity to

make

> this design as interesting as possible. Just to allay any ethical fears.

My

> friend will pay me in full for the parts that I use but I will only get a
> fixed amount for my labour. He knows my intention to make more for my own
> use in the future.
>
> If anyone has any comments please feel free to share them.
>
>
> I am planning to use Maxnc deluxe as the PC based control software for

this

> project but I have been experimenting with Linux my future uses. Last

week

> I bought a book "Red Hat Linux Secrets 2nd ed" which came with a CDROM
> containing linux 2.0.33 (and a lot of other stuff) My intention was to
> install it and upgrade it to 2.0.36. My Hard drive is removable (ultimate
> virus protection when PC is shared with my daughter!) and I went out and
> bought another drive and drawer for the linux install. I founds it all
> quite straight forward following the step by step instructions in the

book

> and I ended up with a dual boot system (Win 98 and Linux 2.0.33). Then I
> went to the Redhat site thinking about upgrading to 2.0.36 and to be

honest

> I started to get confused (a normal state with linux users?) I couldn't

be

> sure what files I needed to download. Finally I shelled out money for the
> Redhat 5.2 boxed set and reinstalled that. So far so good. The I went to
> the EMC site and downloaded the release9J version of RTlinux. I have
> installed that using the instructions on the EMC site and despite the

patch

> file not running clean RT linux appears to work. When I have time I will
> try to install the EMC software.
>
>
> Bob
>
>
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