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Original 1-Axis Controller

1 Axis Controller

Schematic for ULN2803 Controller V2 Schematic (corrected) **AND STILL WRONG**

 

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NOTE: the schematic, as posted, is incorrect. The diodes are backwards. Additionally only V+ needs to go to the stepper not ground. I am going to re-write the entire page once I finish the two axis controller.
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Controller Parts: ULN2803 (datasheet),1N4001 Diode (datasheet),and header pins

I used 2 inputs to 2 outputs to increase the current carrying capability. The Max output current for the ULN2803 is only 500ma. By doubling them up, they can handle a full amp. When pared with the 1N4001, the circuit should be well protected. This should be more than enough for what I need. The power connection is the power for the stepper motor...Which I just noticed that I made a mistake on the schematic (the corrected schematics are posted above above). Pin 10 COM is the Stepper common power (connected to H4 Pin 2 and H3 Pin 1). I will need to redo the schematic and etch another board.

The prototype single axis,if it works, will be replicated for the two other axis. I have an old laptop running Window 98 that will run the DOS based TurboCNC program. I will need to fix up a parallel port adapter to drive the controller.

June 9, 2009: Well, I re-etched the board fixing the little power issue. I have started on the parallel port interface part. Check out this web site: Lab Book Pages. The website has a ton of information on loads of other topics as well.

Etched and Drilled V2 BoardBottom of V2 Controller Board Populated BoardTop of V2 Controller Board


The parallel port pins I am going to use are the data pins (D0-D7), 2-9 (4 pins for x and 4 pins for y)and control pins (C0-C3)1, 14, 16 and 17 (for the z axis). The tricky bit is to remember that pins 1, 14, and 17 are inverted outputs. So, when configuring the software for the CNC machine, you will need to know this. I used pins 18 and 25 for grounds. You will need this to keep your signals from floating.

June 15, 2009: I finished the parallel port interface. Nothing fancy. It is pretty straight forward. I used only two pins for ground (one would have worked). I am using a male connector because my parallel port cable is an extension cable that goes from male to female. You could just as easily used a female connector. If you want to use a centronics plug (the kind that came on printers, you will need to make some interpretations (google centronics plug). You can download the Diptrace files here: PPortDiptraceFiles.zip. I just need to etch and populate. Should take me too long to do.

Parallel Port Connector

Parallel Port Plug

Parallel Port Interface Schematic

Parallel Port Interface Schematic


June 22, 2009
: I coaxed my old Dremel into finishing drilling the parallel Port Interface board. It then promply died. Time for a replacement...But I did get the board done. I didn't have a DB25 pcb mount connector, so I just wired up a cable connector and soldered it up. I may try to source a male DB25 for the final build. Now I need to move on to configuring my software and testing. I will post more on that as I go along.

Parallel Port Interface after transfer

Parallel Port Interface after transfer

Parallel Port Interface Silk Mask

Parallel Port Interface Silk Mask

Completed Parallel Port Interface

Parallel Port Interface with connector


July 13, 2009
: Here is the new Dremel 200 Series tool I purchased. Unfortunately, there is a slight difference in size between the new one and the old one. I am going to have to keep an eye on the alignment. I think next month I am going to bite the bullet and get the new style Dremel drill press. However, it does allow me the ability to continue with the build. I have freed up some weekend time and will use it to build. I had a switch go out and lost a day troubleshooting and replacing it (convoluted network architecture makes it a bit tricky). I have the X-Axis penciled out and will be working on the mockup of it. In the meantime, I am going to be booting up my old Windows 98 laptop and setting up the CNC program for testing. It is going to get really interesting soon.

New Dremel Tool

New Dremel Tool

 

August 18, 2009: I just got my new DB25 Female Signals Breakout Board for the parallel port off of eBay.... You can get one here. It was less than $9 including shipping and it is a lot better job than I did on my prototype. But now I need to make sure I have a male-to-male DB25 or a gender changer (which I am pretty sure I have... I am hoping to test out my prototype of the single axis this week, but I am not holding my breath... Here are the pics of it. Isn't it pretty?

5 Female Signals Breakout Board Top

DB25 Female Signals Breakout Board - top

Parallel Port Interface SchematicDB25 Female Signals Breakout Board - side

 

August 20, 2009: Well, the initial test did not go well. The stepper I am using is a 8.56V .323A stepper. I figured for the first test to power it off of a 9V battery...safer that way. The stepper never moved and after a couple of trys to reconfigure my TurboCNC (TCNC), the battery was very hot. So, that is a failure. The ULN2803 never got hot, so I don't think the chip got damaged (I have spares just in case). I made a cable to go from the parallel port breakout board to the stepper input cable. I need to configure TCNC to just run the pins 2, 3, 4 , 5 in order. I am going to use by breadboard and some LEDs to configure it and see what it is actually doing. After that, I can move on to my X-Axis board.

Parallel Port Board with Stepper-in Cable

 

Parallel Port Board with Stepper-in Cable

Stepper-In Cable

Stepper-In Cable

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