FREE USB-Parallel Port Interface
Released 08/03/2006 - Updated 12/03/2006.
Do you drive your Motor Controller usually via the Printer Port?

Well now you can convert it to USB with this very simple Circuit below.

We supply the PCB design FREE, the Firmware FREE and the Windows Application FREE.
You just build it, use it and let us know of any improvements we can make.
To compliment our new FREE Beta USB Application (Shown Below) along with new Firmware, we are going to release a very simple circuit that people can build themselves that will let you control any parallel port stepper motor controller via USB.

With this simple circuit and our Firmware you will be able to simply plug it into your existing Controller box and using our software, run your Gcode via the USB Port.
The reason this will work with any existing Controller box that uses the parallel port to control the Clock and Signal lines is because we will release standard Firmware that will cover different pin configurations as needed.

If your controller has a different configuration then just email us and we will customise the Firmware to suit your needs and release it on this site. In doing this we hope to build up different configurations to suit all different kinds of controllers out there.


Find below the first picture of version 1.0

As you can see, this is not going to cost you a lot of money to make!!!!!!!!!


PCB and Components.
Please find below the PCB layout.
Size of PCB is 75MM * 75MM



Click here to download the Hi Resolution images.
These are 600DPI JPG and need to be viewed and printed in Adobe Photoshop for an exact scale.
Also included are postscript files as well.

We are also releasing the PCB Layout in Gcode for people wanting to mill their own.

Milling PCB below with 0.2mm engraving bit.

Drilling PCB below with 0.8MM drill bit.

Click here to download the Gcodes.
Inside this file are two Gcodes, one for the Milling and the other for the drilling.


Components:
1 * 25pin socket
1 * 18F4550 Chip
1 * 40 pin Dip Socket.
1 * USB Socket
1 * 20mhz Xtal (the Pic internally clocks this upto 48mhz)
2 * 22pf ceramics
1 * 4k7 resistor
1 * 1k resistor
1 * LED
1 * 0.1uf ceramic decoupling cap.
1 * 0.1uf electrolytic capacitor
1 * 22uf electrolytic capacitor
1 * little tactile push switch for resetting Pic, not really needed.

And a PCB about 75mm * 75MM

Firmware Version 1.2 released 12/03/2006:

Click here to download the Firmware Version 1.2 Type1.
This code is for use with the 18F4550 Pic Chip.
You will need a suitable Pic Chip programmer that supports the 18F4550.
The fuses have all been set in the hex file, so simply load up, Program and Verify.
Type 1 is configured for the following Pin Configuration:

Pin2: Step X-Axis
Pin3: Direction X-Axis
Pin4: Step Y-Axis
Pin5: Direction Y-Axis
Pin6: Step Z-Axis
Pin7: Direction Z-Axis
Pin10: Z-Limit Switch
Pin11: Emergency-Stop Switch
Pin12: Y-Limit Switch 
Pin13: X-Limit Switch 

As we have said before, if you need the firmware customised to suit your controller then please email us and we will re-compile and release here.
Command Structure for Firmware:
Command Structure Ver 1.2 upwards:
Commands are sent 11 bytes at a time.

This first byte gets broken down into 8 bits and they do the following:
bit0= X Axis Direction
bit1= Y Axis Direction
bit2= Z Axis Direction
bit3= Travel kind, this is for the firmware to tell it to use different routines for G00 travelling or G01 cutting, 1=Travelling0=Cutting
If you set this bit to 1 then the firmware will not care about how it gets to this position and it will just clock each Axis until it gets there.
If you set it to 0 then it will move the X and Y axis at even pulses to get to it's destination giving the correct line needed. This option takes more processing time, so speed pauses may have to be adjusted. 
bit4= Tells Firmware to ignore limit switches 1=ignore 0=do not ignore 
bit5= always 0
bit6= always 0
bit7= always 0


The next 3 bytes control how many pulses you wish to send to the X-Axis.
On our machine 533.333 pulses =1mm so to tell it to travel we first have to round up and break to binary int(533.333)=533

533 binary= 00000000 00000010 00010101

now we get our 3 bytes from this

1st byte 00000000 = 00
2nd byte 00000010 = 02
3rd byte 00010101 = 21

By doing it this way we can send a max 16777215 pulses which = 31457MM (103 feet!) Travel

The next 3 bytes control how many pulses you wish to send to the Y-Axis.
This is the same as the X-Axis
The next 2 bytes control how many pulses you wish to send to the Z-Axis.
Same as the X-Axis but this time only 2 bytes(16bits)
Final 2 bytes is Pulse Width Delay
0050 = Pulse delay in Microseconds for speed.
This will differ depending on the Step Mode that the controller box is set to.
Find some examples below, obviously we round up because we only send 4 digits to the controller.