DRV8805?

Hi Sasa,

In reality it depends on what functionality you wish to achieve out of the driver.

For the bare minimum, you should dedicate 4 control lines from the LPT for: nENBL, nSLEEP, STEP, DIR. The line for STEP will need to generate a PWM signal for issuing step commands for the driver. The frequency of the PWM should correspond to the step speed you wish the driver to operate at.

If you know the step mode you wish to operate in and will not be changing it, you may hard-tie SM0 and SM1 to logic low or high depending on the configuration you wish to achieve. If you will be changing your step mode durring run time of the device, you must dedicate an additional 2 lines to control SM0 and SM1.

You will also need at least 1 line to monitor nFAULT. This pin signals when the device has encountered an error and must be monitored by the control program to know when to issue a reset if needed. If you are interested in using the nHOME functionality of the device, another line will need to be dedicated to monitoring this signal as well.

Unfortunately we have no schematics or control software for connecting our devices straight to LPT. However, there are many examples online of people connecting stepper drivers through their LPT which you could use as a starting point for your design.

Hope this helps!

Best regards,
Casey

Thank you Casey for help.

I'm try to make small CNC with this driver. The software that I want to use in this project is KCam. It's easy to use and it needs LPT port. My attempt is to connect only STEP, DIR and nENBL with LPT. SM0 and SM1 will switch manually. RESET on low logic. It's work but, not good enough and now I need second idea. Maybe using opto is solution for my problem.

PS: sorry for my bad english

Greeting

Sasa

Hi Sasa,

Here is a blog post on how to wire stepper driver boards to the parallel port. It has an schematic you can download and study further. http://ebldc.com/?p=399

The optocouplers are not necessary. I have done it without them and there are many breakout boards out there which do not use optocouplers. However, it helps to have some form of isolation as this considerably reduces GND noise and also protects the computer. The computer protection is not needed with the DRV8805, as the device is very well protected, but it is always good practice to have this protection in case something grossly bad happens.

I personally have used MACH3, so am not fully aware of how KCAM operates. In MACH3, there is a configuration term to specify the width of the STEP pulse. This is crucial as the DRV8805 will require the pulse to be at least 1.9 us, so I would configure it to at least 2 us. If the pulse is smaller than this, then it will be ignored. I imagine KCAM has the same setup parameter.

Another thing that you have to take under consideration when using the DRV8805 is that the stepper must be resistive enough as to limit the current. You can also apply the exact voltage and this will work as well, but if you are trying to push to much current, then the device will enter Thermal Shutdown Protection.

I have personally built CNC machines with DRV8811/18/25/28/29 and have to say these devices work extremelly well! I never thought of using DRV8805 but I am glad somebody did! Keep us posted on how it works for you.

Best regards,

Jose Quinones

Thank you Jose very much.

My people use to say for those who forgot something to do: `` Someone who haven`t anything in a brain, have something in a legs``. Well, I forot to read cearfully the DATASHEET for DRV8805. Page 8. are explain everything about inputs nEnbl, STEP, RESET, nHOME. Those Tables3-5 explain to me what I need to do to move my stepp motors on.

I will try to make some kind ``predriver`` for DRV8805.

Every suggestion are good one in this time.

Sasa