Build Thread- Controller using UDN2916LB Chips

[zerodegreec]

I am staring to build a controller using Dual Full Bridge motor drivers (UDN2916LB). I would like to run this chip off of a parallel port.

I found some useful info but I am not sure what to do for the parallel port interface. I have no problem making the circuit etc. On page 5 of the datasheet it has a typical application diagram. I found some additional info on a project using this chip but interfaced by a EEPROM. I dont have access to a EEPROM programmer (I did 16years ago). So all I need to do is find a way to control pins 16,17,20 and 8,9,10. These are the logic inputs and the phase input for each winding.

ANY help would be appreciated.
Thanks,



BTW I will make a step by step for others to use and to refresh my memory in 5+ years when I desperately need to remember how I did it (if I actually get it figured out)

[doorknob]

A few comments from a quick look at the datasheet.

First, just to be sure, you understand that the max rated current output looks like 750 ma, which is pretty anemic for driving stepper motors typically used in DIY CNC machines, right?

As far as controlling the pins that you referenced (in the typical application circuit), it appears to me that I0 and I1 are used to select the actual current used to drive the motor windings, and so, unless there is a reason to adjust that value dynamically, it looks like you could either hard wire those inputs to the appropriate logic levels, or else connect them to DIP switches. I don't think that those inputs are intended for use in microstepping, but maybe I have overlooked something.

That leaves the "phase" inputs, which are used to switch the bridge configuration from conducting through one path or the other of the H circuit.

The remaining question would appear to be how to control the "phase" inputs from a parallel port (I am assuming that you mean that software such as Mach3 or EMC2 is actually controlling the parallel port). My best guess is that you will want a microcontroller to handle that part of the job. You need to translate from a "step and direction per axis" input from the parallel port into the proper phase sequence to apply to the chip. To do that, you need to follow a phase energizing sequence table (from any of the typical "introduction to stepper motors" articles) - by making a simple state machine in the microcontroller's firmware, and using that to interpret activity on the step and direction inputs according to the current state of the phase drive that is applied to the motor.

I don't know if you could handle that translation directly via an EPROM or not (I'd have to think that through a bit - but my guess is that at a minimum you'd need at least some logic circuitry between the parallel port and the EPROM, and if that's the case, it would probably be easier to just use a microcontroller instead of the EPROM)

So, I'm not sure whether any of that helps you or just confuses you...

[zerodegreec]

No you have not confused me. I was hoping I did not have to put a much between the PWM chip and the Parallel port... Oh well. More research I guess.

And yes I know that they cant handle much power. I was planing on a small application. BUT I cam across people using printers and scanners for small application/light duty. I believe this chip cant run the motors used in printers etc.

Into the shop I go... have some old printers to rip apart and see what I can use.