[barmybovine]

Hey all

OK I have built 4 picstep boards and a 4 axis interface. I am trying to verify that the pic steps work on their own before hooking up the interface. I cannot get it to work

I currently have a a cable setup to test them as shown in this link

http://pminmo.com/troubleshoot.htm

I have it wired as a bipolar. With the enable and dir pins both going permanently to ground and a N.O. switch on the step pin. I have an external +5v supply to the pics and about 30V top the motors. I have tried several of the boards and have the same symptoms on each board. I am using Pic 16f628A i/p chips which I believe should work ....correct?

The symptoms are as follows when programmed with the 20 Mhz codes using the default settings when programming the chips ie. HS oscillator WDT,PWRT and BODEN enabled and everything else disabled <not a pic expert at all>
it programs and verifies fine.

When I fire up my power supplies I get a quick vibration from the motors then nothing switch the step seems to do nothing also the motors are not locked in position as I can easily rotate the shaft. As I turn off the 5volt supply I get the same motor vibration. I have also tried pulling the Xtal and caps and programming the 4Mhz codes both have the same symptoms. Just for a laugh I tried programming the pic using ExtClk as the oscillator and this makes the motors go crazy ....randomly vibrating and spinning with the step pin seemingly having no effect on the motors conditions.

Like I say I get the same symptoms on multiple boards so dont think its a problem with the PCB's themselves. Any input would be GREAT....I have been building my machine for 6 months and was REALLY hoping to get it moving under NC control this weekend.

Thanks guys

Scott

[pminmo]

which version of the picstep? did you select current limiting resistors to match your motor requirements?

[barmybovine]

Thanks for the reply

Version 4.0. I am going to try interface to your 4 axis bard once I get the pisteps working

I have 2 X 7.15K resistors installed in each board to run my 2.8A motors

Thanks
Scott

[pminmo]

Did you realize the orientation of the 10 pin connector on the V4 is 180 degrees different than my boards?

[barmybovine]

yes i made sure to match up the pins between boards. I am not using an IDC cable. I am using a 5 pin connector to wire in enable\dir\step\GNd and +5V

At the moment I am trying to get the pics running without the interface and just using the same 5 pin cable with an IDC header plugged in one end so I could short enable and dir to GND whilst having a N.O. switch wired between the step pin and GND


Thanks

[pminmo]

What is your power supplies current capability?
It sounds like you don't have the motors enabled, since your motor can freely turn with power on. Any pictures ? maybe there is a clue that would be visable.

[barmybovine]

I am using a bench supply that can do about 8 amps @30V I dont have pics.
My camera is at work but I could run and grab it if needed. I should take enable LO ...correct?

Thanks

[southernexplore]

He may need to enable the pic. That was my problem when I first started.
Tommy C.

[pminmo]

Tommy, not sure what you mean? The Brake/Enable on pin 1? Does you have to set a 628A's clock source when you program it? I'm not a PIC kind of guy........Not yet anyway.

[barmybovine]

same here o the pics. I checked into that and by default as you load the HEX code into ICPROG it selects HS as the oscillator. I believe that to be an external clock above 4Mhz . I have tried running at 4mhz <int osc> with the 4mhz code and the Xtals removed but still the same. I get the motors to vibrate and turn but in a random fashion when I select ExtClk as my oscillator during pic programming. When programmed this way , if I pull the enable pin from my connector the motor stops all together and can be rotated once I reconnect the enable line the motor starts to freak out again so I believe I have enabled the motor by taking the enable line LO

I feel like it is something simple stopping them I just cant figure it out.

Thanks guys

[pminmo]

Right off the top of my head, I don't have any suggestions. Maybe somebody that uses a PICstep.

[southernexplore]

When I started I did not know anything about any of this either. Through trial and error I was able to get mine going and they run great now. I did let some smoke out a few times but when I learn the hard way I usually do not forget.

My boards would not run until I ran a jumper on the 4 axis BOB to pin 1 on the 10 pin connector. I believe it has to be pulled low to run, if my memory serves me correctly. Also be sure and use the std firmware because the hi torque version did not work for me.

Tommy C.

[barmybovine]

Thanks for the reply tommy

I have the enable pin <pin1 > soldered to ground on my test cable. I am trying to run them as indicated in the link in my first post. I will double check and load the STND firmware . I have tried so many vaiations I can;t remeber what happened with the standard F\W

Thanks guys

[barmybovine]

Tommy can you remeber if you programmed it using the default config ie using HS for oscillator WDT, PWRT and BODEN enabled ?

Thanks

[barmybovine]

Good news. I loaded up the standard version of the S\W and its working now. I guess I hadnt tried that earlier. I should write down what I am try whilst using the old trial and terror technique

Cheers Guys.

[barmybovine]

Hey guys....Sorry to darken your doorstep again

I have had the motors running fine on the bnch at up to 105ipm with no probs and couldnt stop them rotating by gripping the shaft in my fingers.

I mounted them to the table and as expected had to lower the speed to compensate for the load of being on the machine.

I can only get em running at around 30ipm on each axis before stalling.
I am using 2.8A Powermax II motors <I intend tto get servos some time in the future >. They are not the biggest motors in the world but I am sure they should run better than this. So I got an ammeter on the motor supply input into the picstep boards and found I am only drawing 400ma stationary and 600ma running at 30ipm .

i have the current sensing resistors on the boards set to 7.15K ohms.I am running the motors in parallel Bipolar mode and even lke this they only draw the above current.

My supply is more than capable of the supply current needed. It is 35V at 20A.
I am using 20AWG cable of about 20 foot in length for the motors. I understand that this is a little on the small side but it is more than capable of handlling 600ma. I have checked and triple checked that my motors are wired correctly.

Any ideas would be great as I am so near to having this sucker up and running. I have attached a pic.

Thanks guys

[pminmo]

Are the motors 6 wire or 8? If they are six wire, don't use the full coil. Use the center tap to one end. Don't place any value on the measure current unless you have true RMS meter. Your machine looks great!

[barmybovine]

Thanks Bud

I am measuring the current on the input to the board when its just plain old DC ....Surley the measurments taken there should be close to the 2.8A?

I know another guy using these motors and getting 100ipm rapids. Also even when I am running at 30ipm just a slight bit of pressure from my hand on the gantry will stall the motors. 30ipm is right on the edge of them moving the axis any cutting force applied would for sure stop my table.

I just know they will work better than I have em setup at the moment.

Thanks again mate

Scott

[southernexplore]

Do you know what the inductance is on the motors? A motor with high inductance will not turn very fast before torque drops.

What is the voltage rating on the motors?


I have my PicStep boards runnig at 47 volts and 3 amps (lots of cooling) with 265 oz. motors and I measure a current of about 1.9 amps measuring each wire as it come out of the picstep drivers going to the motor.
I think this is pretty close to what it suppose to be.
What lead screw are you using?

Tommy C.

[barmybovine]

OK inductance on the motors is 0.7mH parallel and 2.8mH series. The motors are rated at 5.6A parallel and 2.8 series. I found they ran worse in series but could get them up to a nice speed and could not stop them turning by gripping the shaft with my fingers when ran in parallel. The way they are now the machine is useless. I intend on getting bigger stepper\servo's in time but I just know that I can get much more out of the one I have now. As you stated southernexplore you observed you measured 1.9A on the OUTPUT of your picsteps for a 3Amp motor so it stands to reason I should be seeing at least that on the INPUT to my boards.


http://www.motionvillage.com/product...e/p2m2_cat.pdf

Anyone know if there is any special requirment on the type of resistor used for the current sensing resistors on the picsteps? I am using 1% 7.15k metal
film resistors all of which are brand new and were checked for accuracy before installing them.If i parallel another resistor across the 7.15k for instance a 100k in parallel will give me roughly thr required value for 3 amps and I still dont draw anywhere near that.

Man so near and yet so far. I can almost smell that beautifull smell of fresh cut wood. :tired: