Re: Projects Status (Dan Mauch)

> From: "Dan Mauch" <dmauch@...>
> My next project is to redesign my 5A controller so that they are individual
> modules with jumper selectable full/half step, all wingings off and what
> other features creeep into the process. I really like to add microstepping
> but don't have a clue on how to program a PIC chip to replace the PBD3517.
> I'll also make a 4 maybe 5 axis opto isolated junction board to take the
> signals from the parallel port and distribute them to the modules. This way
> you can have 3/4/5 axis if you have a power supply large enought to handle
> it. It should help if you want to use the controller with a plasma cutter.

I know this is a pretty old message to be replying to, but I'm in the process
of mounting my 5A board and I though I'd add my comments if it's not too late
to influence your design decisions. I guess what I want most is for the
board's outside dimensions to match a DIN rail mountable housing such as
Phoenix Contact's UM series. See:

http://www.phoenixcon.com/products/housings/

Near the bottom of the page is the UM72/100/108 series of PCB holders.
Basically, you need to make your board 4.23" wide x however long and stay .1"
inside of the board's edge. Another helpful change would be to adopt two
piece screw terminal type connectors for the I/o. These allow easy
termination of cables as well as the ability to unplug the whole connector
from the board. They are manufactured by Phoenix, Curtis, and a couple of
other companies I can't remember at the moment.

Electronic issues:

1. Jumper selectable full/half step, all windings off - OK

2. Microstepping - might take more work than is practical to attempt, however
I'm a fair hand with a PIC so let me know what your ideas are.

3. Junction board - I vote for 4 axis since that's the number that can be
supported by one byte of I/O.

4. I'm not sure what to do with the 555 circuit, either leave it off (or make
another board with just that), or put one on each module, but use a pcb mount
pot and direction switch. The second option may be the best as folks could
stuff it or not as they please.

5. It's probably a good idea to put a 5V regulator on each board, but bring
the 5V signal out to a screw terminal in case folks want to leave off that
circuitry and supply 5V from an external supply. Also, some change ought to
be made that would eliminate the big ceramic resistor. I know you need to
drop the input voltage to the 7805 to avoid having it burn up from excessive
power dissipation, but another solution would be welcome.

6. Speaking of voltage, increasing the max input voltage would be great!
Perhaps something could be done with logic level gate type MOSFETs. I haven't
thought this through, but I wanted to mention it just the same.

Thanks,

Matt