Thanks Lucas,
I will contact the seller,
Best regards
Terry
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Unfortunately, no. All stepper motor drivers are not created equally, so to speak. It's necessary to examine the details to understand what functionality is provided by a particular "driver" and what is not.
The rotary table indexer circuit outputs step and direction signals which in turn are used to control a driver that is designed to accept step and direction signals as its input.
The aforementioned L298 driver board is not capable of accepting step and direction inputs by itself. Rather, it only comprises the electronics that can energize two coils in one polarity or the other. Additional circuitry would be required to provide the logic that translates the step and direction signals into the proper sequence of coil energization and de-energization that will result in the desired movement of the motor. Other circuitry could also be added for the purpose of limiting the current drawn by the motor, or for microstepping, or other desired features.
There is an IC called the L297 (that is designed to handle some of that functionality) which is often paired with the L298, however the board to which you linked does not have the L297 circuitry built in.
As an alternative, theoretically you could modify the firmware of the indexer board to handle the required logic, however my understanding is that the source code for the indexer has not been made available, and so that task would entail designing and coding all of the logic from the ground up, which would be a major undertaking.
Hi Simon, I'd go with post #33 (I'd probably actually tried those to make sure they work). I haven't checked the circuit diagram so can't comment - but that was drawn from the finished circuit. (I built it on a breadboard then drew the circuit once it worked...)
My pcb layout was checked with the Farnell keypad, beyond that...
Most keypad problems can be resolved by considering the keypad to be two sets of 4 wires.
If the keypad is rotated 90 degrees (i.e. the rows and columns are swapped) then swap the two sets wires over.
Then if the keypad is flipped top to bottom flip over the 4 row wires.
Finally if the keypad is flipped left to right flip the 4 column wires.
(It helps here if the keypad cables are two reversible 4 pin plugs...)
If I knew then what I know now I'd have added the ability to reprogram the keypad from the software! (Perhaps if I get some spare time)
Cheers,
Steve.
Hi guys
My indexer is up and running and just needs boxing up.:D
I must thank all of you who took the time to help me get to this stage it is most appreciated.:cheers:
Thanks especially to Steve Ward for software and support and to Lucas for the board design.:cheers:
I will try and add photos when its complete. :wave:
Thanks Steve & Lucas,
It pays not to do stuff late at night when I should really be getting some zzzzzzzz!
I have a cheapie keypad (Same as Jhovel) and the pin placement seems to follow no known standard! With the keypad you used, the keys can be labelled at will and so it opens up many combinations. Should have gone with that!
Lucas, I never doubted you! Like I said, late at night things seem a little fuzzy...:confused:
On another note, I'm planning on using this stepper driver with a nema 23 stepper motor for my 8 inch RT.
Single Axis TB6560 3.5A 2 Phase CNC Stepper Motor Driver Board Controller | eBay
It says the inputs are optically isolated and so needs input resistors. It states a 1K resistor for 12V controller signals, so could I get away with a 500 ohm from the controller given the approx 5V outputs? That's about 10mA output, would the chip do this or should I add a couple of output transistors to drive the output and keep the current low
Thanks,
Simon
Roughly speaking 12v and 1k is around 10mA.
(12v minus 2v for the led forward voltage drop divided by 1k).
So for 5v you need 3/0.01 = 300, so call it 270 ohms.
10mA is well within the current source/sink capabilities of the chip so I wouldn't worry.
Hi,
I have a 4" rotary table similar to this one. What size motor can I get away with, does anyone have any suggestions. ARC Eurotrade suggest a 180 Ncm stepper, That seems a bit overkill to me, what have others used on this size table (1:72 worm ration).
Besrt regards
Terry
You could certainly use a smaller motor, probably I'd go for the same 'footprint' but half length.
(Although unless you need a smaller one I'd be inclined to go with the 180).
I use a 180Ncm one on my 4 & 6 inch tables (1:90) and I often bolt the 4 inch version to the rear of my lathe to directly drive the lathe head for indexing which it does with ease.
Hi,
Sorry about this, it appears to have posted twice, Thanks Steve for your comment, much appreciated,
Besrt regards
Terry
Got mine working.
Redrew the schematic and board in eagle if anyone wants to use it.
Attachment 174733
Attachment 174734
Attachment 174735
Attachment 174736
Attachment 174737
Attachment 174738