[Coco] [coco] Coco CNC

[Gene Heskett]

On Wednesday 13 February 2008, George Ramsower wrote:
>From: "Gene Heskett"
>
>> Yeah, I've been meaning to ask how the coco is actually interfaced to the
>> motor drivers, can you clarify that George?
>
> Gene,
>
>  Years ago, I built an interface board that connects to a Y cable. On that
>board is a 1 of 16 decoder addressed to the last bit.
> Also there are four 8 bit output latches and four input buffers. This uses
>a total of eight address spaces starting at FF60.
> FF60-FF63 are the output latches. FF64-FF67 are the inputs.
> Those are wired to DB-9 connectors. Those outputs are connected to an
>external box that has a 24V power supply and four ea. four darlington
>transistor arrays that step up the 5V signal from the coco and provides the
>current for the steppers.

No dmos h-bridges?  They are the ideal motor driver.  See the Alegro A3977 for 
one version.

> In that outside box is also a provistion for one input array to one of the
>input buffers on the coco. Right now, I'm only using three bits for  the
>three home switches  on the XYZ axis'.
>
> It's really quite simple.
>
> FF60 is the X axis. It uses only four of the eight bits and so on..
> Originally I put two steppers on one latch, but the math slowed the poor
>coco down. Since I only need four axis, one per port made more sense and I
>switched to that ideal.

Sounds like the nearly ideal situation. I can visualize it nicely. Unforch for 
EMC, the pc's existing parport was the chosen interface for EMC, and if it 
weren't for some smart software, that port would be a bit crippled, but we 
can run 4 motors and tally the home switches for a 4 axis machine plus a 
surface probe, using just the parport.  But I have another dual parport card 
that will be installed when I switch the driver from a 3 axis board to a 4 
axis board, and that will let me do a few more things, like run the lathe 
too.  But that is down the road, possibly to a bigger lathe before that gets 
wired up as the carriage on this one would be hard pressed to support even a 
262 oz motor.  The bigger lathe means a bigger building, and that's self 
feeding until the account is drained.  Darnit.

> I built this coco for the purpose of home security and just playing with.
>But when I decided to make a CNC machine, it was already set up (hardware
>wise) to do this. I didn't have to modify the coco at all. Now, when I want
>my security thing, I just unplug the CNC machine and plug in the security
>stuff, pop in another 3.5" floppy, reboot and viola! A computer can be
>whatever we wish.

Limited only by our imagination. :)>

> What FUN!! I love my cocos!!
>
> This is almost as good as sex!!...... almost.
> Anyway, it's a danged site better than TV, now that the Writer's Guild is
>taking a vacation.
> Damned unions.
> Greed is why we are approaching a recession. I could go on and on, on that
>subject, but there's not enough room in my coco for all what I think on
>that.

And to expand on that, the large fraction of a terrabyte worth of disks in 
this box still doesn't have room for my opinion on the subject of greed, and 
it certainly isn't printable.

-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
It's reassuring to know that if you behave strangely enough, society will
take full responsibility for you.