Robot Arm Parallel port programming

Projects General Guidance
1

I just got a eduicational robot arm from the 80's that was programmed from a computers parallel port.

Since the control board powers up and I would like to continue using it.

But as a nube Im not sure how to do this.

The 4 bits for the stepper control have to be cycled to operate the motors.

Ive attached a schmatic (PDF)

Here is the data I need to send

D7 D6 D5 D4 D3 D2 D1 D0

Note: (bit D0) this bit must toggle because they trigger the
74HC259 latches.

Bits D5, D4 and D1 select the motor being
controlled:

Aux #1 000
wrist 001
gripper 010
wrist 011
elbow 100
base 101
shoulder 110
Aux #2 111

Bits D7, D6, D3 and D2 are the output to the stepper coils.

schematic.pdf (30.4 KB)

2

Do you want to control it with a pc parallel port, or via an arduino?

3

Here's a picture of what bits the stepper should receive to rotate.
Unfortunately the picture only shows a stepper being driven in 1 direction, but by giving the same pulses in reverse it will turn the other way.

Microstepping will unfortunately not be possible...

4

I want to control with my Arduino mega

My current wiring has each of the 8 bits wired to an output on the mega.

I can set the 3 bits for the motor address.

I can pulse D0 to reset the latches

Im even using the Stepper libary to send the pulsed which i also verify with leds.

My first question is unlike serial which one bit follows another

Parallel is were we send all bits together? correct ?( I'm not sure)

What i tried so far is

i set the motor address first D5 (low) D4 (Low) D1 (high) this selects the Wrist stepper

Then I toggle D0 the Latch it

Then send my pulsed to control the motor using D7,D6,D3,D2.

I think i'm misunderstanding the way to send the data.

do i have to send all 8 bits with the changing step sequence each time
or or do i just toggle the 4 bits to move the motor.

I hope i explained it ok.

thanks