Re: unlurking

Thanks for you comments Ted,

The EEPROM was to store constants. During the installation you would hook
up the serial port of the stepper driver to a PC and using a 'terminal"
program set up all the driver constants. You would only have to do this
again if you changed the motor or machine load in some way.

The normal use of the stepper driver would be by the step and direction
signals derived from the PC parallel port.

The wall wart is just for the driver logic supply, I don't want to have the
ac mains voltage coming onto the driver PCB. The motor power supply is to
be a seperate one chosen to match the number of motors and their power needs.

The optoisolators also help keep the motor voltage (up to 80V) out of the
PC if a fault develops in the driver.

I liked the idea of solder ball jumpers too and I would have needed 25
switches per signal (step, direction etc) to have the same flexibility.
That is a lot of dip switches! I will think some more about this, maybe
there is a way to please both camps.

Another idea that I have had is to generate 'softsteps' (my own term). If I
were to put a one step delay into the stepper driver software, I'm assuming
that one step delay is a negligable error, then I would know the time
between the last two steps received and I could make the driver evenly
microstep the motor over this time without the host PC knowing about it.
This would overcome mechanical resonance problems. I would catch up the
lost step at the end of the move. I haven't really thought this through
yet. so there is probably a reason it won't work but I like the idea that
the CNC software does full steps but the driver does micro steps.

Once again thanks for you reply.

Bob.


At 10:43 28/06/99 -0700, you wrote:

>From: "Ted" <rtr@...>
>
>>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.
>
>