dont use delay - its too slow

I think the trick was to do a port read ( one of the status bits or
something equially arbitary ). Those take 1 microsecond

The fastest i was able to go was about 50 us before the stepper started
skipping beats. It also depends if youre half stepping or full stepping. I
also suggest you use a tranny of some sort as the pc par port can let out
its smoke if you draw too much from it. I used normal TIP31's as i had a
whole box full of them.

I found full stepping, but with 2 coils energized ( half step position, but
full step increments ) gave me the best torque.

John

-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Pramod Kotwal
Sent: 28 December 2000 10:55
To: PICLIST@MITVMA.MIT.EDU
Subject: [EE]:writing data to IBM PC parallel port to drive stepper


This is about using an IBM PC parallel port to drive a bipolar stepper
motor. So I hope it not too far off topic here.

I would like to use C to to send the appropriate signal to the data port
bits on the parallel port. P.H. Anderson gives a very nice and clear
explanation of how to do it .

The problem I have is in defining the delay between two subsequent commands
to write the bit to the port. This time interval will define how fast the
motor will turn.

The command to wrie data to the port is
outportb(port address, data).

The interval between writing data is controlled by the
delay(time) command.
This command seems to read time in milliseconds.

If this correct, the shortest delay I can specify is 1 millisecond between
steps. This would mean that on stepper motor with 200 steps per revolution I
can, at best get 5 rpm.

This does not make sense to me. Where am I going wrong ?

I will appreciate help.
Pramod Kotwal

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads