Re: 5-axis machine controller

[Ray <rehenry-at-up.net>]

On Wed, 20 Dec 2000, Marc wrote:
<S>
> I'd like to toggle the bits on the port and drive the stepper coils directly
> thru FETs. I figure a 3-to-8 ttl Decoder and 3 latches along with a dozen
> Transistors should do it. I have all that stuff close at hand.

>From the EmcSoft.html in emd/doc directory

The pinout for the EMC stepper motor interface is as follows: 

Output        Parallel Port
------        -------------
X direction   D0, pin 2
X clock       D1, pin 3
Y direction   D2, pin 4
Y clock       D3, pin 5
Z direction   D4, pin 6
Z clock       D5, pin 7

Input         Parallel Port
-----         -------------
X/Y/Z lim +   S3, pin 15
X/Y/Z lim -   S4, pin 13
X/Y/Z home    S5, pin 12

Stepper motor control is implemented using a second real-time task that
runs at 100 microseconds. This task writes the parallel port output with
bits set or cleared based on whether the a pulse should be raised or
lowered. This gives an effective period of 200 microseconds for a full
up-and-down pulse, or a 5 kilohertz frequency. 
--

Ray