In my naivety, it seems that I have another problem or two with my project.
I had intended to use the stepper pulses from the BOB to the driver and multiply (in the code) by the number of microsteps that the driver is set at and using the significant numbers of the result divided by 100 to give me two decimal places of travel per millimetre. The resultant output pulse would go to cascaded CD40110B up-down/latch/drivers which would either be to the up input or to the down input depending upon whether there was a 'DIR' signal present from the BOB (does that make sense?). I have attached the circuit which gave me the basis for my idea below.
Using the spreadsheet at:
https://www.machsupport.com/forum/index.php?action=dlattach;topic=16315.0;attach=23771, I decided that the setting for 64 microsteps would calculate at 7314.28571 per millimetre travel using 1.75/mm pitch lead screws. Using the significant numbers divided by 100 would require 73 pulses per 100th millimetre with an error of about 0.143 pulses which, if my dubious math is correct, would equate to a total error over the full travel of my X axis (1700 mm) of 2.43mm.
Assuming that I am correct in my calculations (and theory), that brings me to another problem. I had toyed with the idea to route the pulses from the BOB through some form of Schmit Trigger circuit to clean them up but have no idea of the resultant frequency or pulse width and do not know whether the PIC16F677 processor will be fast enough to handle the data (20 MHz clock, 200 ns instruction cycle).
My machine configuration is:
X, Y and Z axes all on 1.75mm pitch lead screws with tapped sintered bronze drive nuts followed by HDPE anti-backlash pads with:
X Axis - 4NM 60BYGH401-03 stepper motors x 2 driven by separate drivers from the same BOB connection.
Y Axis - 4NM 60BYGH401-03 Stepper motor
Z Axiz - 3.1NM 60BYGH301B Stepper motor
I also have a fourth (rotary) axis using a 2.2 Nm, 3.5A motor (designation unknown) at 1:6 ratio which would only be used with X and Z axes.
I hope that this explanation is not too long winded and would appreciate further help.