Open source firmware and board layout freely available
Low parts-count and cost for home building
Low kit price to get running on a budget
Smooth / low resonance modes for better performance
Faster / more reliable operation w/ low cost surplus motors
technik, I would check the step pulse signal (with a scope if possible) to see if it is getting high enough. It sounds to me like it's on the harry edge of failing to be seen at the PIC and when you increase the PIC's supply, that shifts the voltage level where a signal is seen as a 1 vs a 0. You might have a PC with a "weak" parallel port (still in speck, but not driving the pins as hard as most) or a bad connection on the BOB or other connector. Also the timing setup in your CNC software may need to be adjusted so it produces a longer pulse, giving the parallel port drivers time to pull the pin to the correct level. If you find that's the issue, you can also adjust the value of the pull down resistors on the Linistepper board to adjust.
Or it could be something totally different. I'm a software/firmware guy, not an electronics engineer at all.
I just saw this, and I agree with James.
It's very unlikely the difference between a PSU of 4.8v or 5.0v would cause any issues with the Linistepper itself.
It could be with your parallel port. Try putting pullup resistors of 1k on the step and dir inputs (and to +5v). The parallel port is good at pulling the logic level low, but can be weak at pulling it high so the resistors may completely fix your problem.
Hi folks!
Thanks a lot for your help! I tried to modify the pull-up resistors at STEP and DIR channels but without success. I measured the voltage level on the parallel port of my PC, it was around 3.3V (logical 1). I think using a 7407 buffer IC on parallel port output wires can solve the problem. I will inform you soon about the results.
Hi!
Finally I have my steppers working and they are working fine. I used a CD4050 non inverting hex buffer to produce 5V at the STEP and DIR inputs of the microcontroller. During the tests I discovered that torque of the motors with the 3 boards is different. I have three PIC16F628 processors. One of them I bought a few years ago (it has different id. then the others and the motors has higher torque using this processor) and two I bought these days. I tried them all in the same LiniStepper board but the results are different. Today I will check it with scope, maybe I will see what is the problem.
Thanks!
The polarity of the full/low power line was inverted from version 1 to version 2. Try changing that line while the newer chips are installed.Originally Posted by technik
Do you mean I should connect the dip switch to GND instead of +5V?
Not the entire DIP, no... that would affect all the lines controlled by the DIP switch... Just change the setting for the low power aka enable line. Just that one pin.
OK, I changed ENABLE line to high, now the motors has the same torque. But why only the newer chips requires high state of the ENABLE line? What is the difference between old and new PIC16F628? The firmware is the same for all controllers...
The firmware is different from V1 to V2. The enable line polarity was changed to be more compatible with the PMinMO standard connector which the V2 PCB supports. This allows one break out board to be used with many different drivers such as the Linistepper, SLAm, and others at the PMinMO site.
Thank you for the quick reply James. I have three V2 LiniStepper drivers and V2 firmware for all of them. The only difference is the PIC16F628 revision number. So I can't understand, why the full power can be reached by ENABLE high in one case (rev number) and by ENABLE low in other case(rev number).
I honestly have no idea.
Any one post a complete,linistepper ver 2,pCB,hex
thanks
Thanks ????
do you have db25 interface board...with ne555 ...send me a PCB ,and schematic.. eagles files..
OR USB INTERFACE BOARD with PIC.. send me hex and schematic eagle file.. thanks
I will connect the linistepper.. ver 2
complete stepper driver
I've been working on putting togeter a complete stepper driver for use with 1 to 4 modified linistepper boards(not pminmo compatible)..
The breakout board is fully buffered on all the outputs and all the inputs and should be easy to modify for pminmo connectors.
See what you think about it..
This is still a work in progress and I havn't built one yet so....
Sam, I don't suppose you could post a screen shot of the schematic for those of us who don't wish to install Eagle.
hello
i don't use eagle either.
a screen shot or pdf would be nice
thanks
Here are the PDF's
I saved them as pdf files
Hey Sam, Looks ok to me...
Curious what led you to those MAB6H connectors? No concern, I just wondered...
I would not use the SIL connectors as the cables are expensive. Ribbon / IDC is so much cheaper and works just fine. But if that's what you have/like so be it.
You might want to add some extra holes for additional power resistors... it's difficult to tune for more or less amps with only one resistors.
I've never been terribly impressed with buffered parallel port boards... if they aren't optically isolated, they aren't going to stop a spike killing the computer, and the vast majority of PC parallel ports work just fine... it's not like they have to drive much of a load. But some people swear by them, so who am I to say otherwise?
Your BOB looks ok to me. No obvious problems. Once you have a chance to build and test, would you like me to post these to the Linistepper web page?
Reply with Quote
