Peter:

I take it that you have not done any work with CNC machinery. When you are doing complex contouring you MUST be able to vary the speed of the motor. Not only do you need to control the speed while cutting material, it is also necessary to ramp up to speed and then ramp down to speed you NEVER EVER try to stop a servo motor instantly or too quickly as you are moving a fairly large amount of mass/weight with the motor, such as a 4' X 8' steel or aluminum table or a heavy cast spindle head. Either of these can weigh several hundred pounds and you are moving them with low horsepower motors in many cases, no more than 2 hp usually. You must vary the speed when you are changing directions in wood to prevent "blowout" of the grain or laminate etc., also in order to get the correct type of corners and smooth cuts with the tooling.

The URL for J.R. Kerr is www.jrkerr.com

They use Pulse Width Modulation to drive a small current amplifier however you can take those same pulses and feed them into an operational amplifier with some resistors etc. and get an analog +/- 10VDC out. This is what I am doing now.

I know what I need to do, I just want to know how to do it with an 8052 device. I want to take step and direction signals generated for use with a stepper motor and input them into an 8052 then be able to output a digital signal that I can convert by DAC to the +/-10VDC signals I need.

Please keep in mind that the amplifiers, motors and encoders are already present on the machine from the previous controller.

Randy Abernathy