[arvidj]

...

Basically you've exceeded the resolution of the internal maths.

It calculates a value for the number of steps per 360 of the table which in your case is 200 * 90 * 10 = 180,000.
However it's a 16 bit number so the max it can be is 65535.

...

What you need to do is change the 1/10th micro step to half step (i.e. 2 steps instead of 10). In this application there's no point in microstepping anyway.

...

Steve.

Steve,

Is there any chance this 16 bit number will be increased to 32 bit in the very near future?

I am ordering parts from Mouse and would like to stick with my current selection of Gecko drives but the inexpensive ones are all fixed as 10 microstep drives. My 8 inch table has what appears to be the ubiquitous 90:1 worm ratio so I will exceed 65,535 on the count. I'd rather not pay considerably more for the flexible microstep drives.

By the way, I am ordering both the '452 and the '4520 PIC's and should be able to test them both ... assuming my PICStart Plus programmer really can burn the '4520 with the Microchip recommended kludge.

Arvid

[gandalf1]

Hi Steve,
At long last it is Alive!!!! It has only taken 5 years along with one Fried Display and Chip to get there, now it only needs a bit of tidying up of the wiring around the motor to look presentable. The Divider is controlling a home built dividing head with 36:1 worm, 19 volt laptop power supply and a cheap Chinese single motor driver. A few little problems but all seems to work fine now with 19 volts to the motor, 9 volt regulator from the power for the divider circuit and the 5 volt output from the divider to work the opoto isolators on the driver. Obviously not as accurate as a higher worm ratio but adequate for my needs. Great thanks to you for the design and to Malcolm (mp3) who has put up with my efforts, failures and programming PICs over the last 5 years.
Out of interest after Frying the PIC and display both of which were replaced Malcolm has not only programmed my second PIC but has managed to re-program the original which is what I am now using.
Anyway thanks to both of you as I can now go round in circles and stop where I want to. Now have to get the Yellow Peril back together again and start cutting toothed pulleys for the two speed belt conversion.
Thanks again Guys for your help and assistance.
John.

[miljnor]

congrats.....where are our pictures!!! =)

[gandalf1]

Nothing spectacular to be seen,
The divider circuit is underneath the display and attached by a row of pins soldered to the display and which push into a row of sockets chopped from a DIL socket. The motor driver is a cheap Chinese one off EBay and in my case set for 1 amp per phase, it is mounted beneath the keypad and all is attached to the front panel. I use an old laptop power supply giving 19 volts but have fitted a 9 volt regulator for the divider circuit (fried the first attempt with a 19 volt supply), this 9 volt regulator is attached to the side of the motor driver heat sink. The motor driver needs a 5 volt supply for the opto isolators so is taken from the 5 volt output of the divider board however suspecting this is what initially failed I replaced but have added a small ribbed heat sink. Apart from setting such things as number of divisions or degrees the set up is as I received it from Malcolm so I assume is as the PIC was programmed.
Not much else to say really, I found a 36:1 worm and wheel many years ago so adapted an 80 mm self centering 3 jaw chuck from conventional backplate to the worm wheel, fitted it to a tilting base mounting for no other reason than it seemed a good idea at the time and promptly put it away and in some 12 to 15 years have used it ony 2 or 3 times. However I now need some toothed pulleys of non preferred numbers of teeth so the also lying dormant divider scheme was brought back to life. I next need to make a back centre to support an arbor when cutting the pulleys but whether it was by design or more likely it just so happened the centre height is conveniently 60 mm.
This evening I will attempt to tidy up the wiring around the motor and fit a thinner but also longer and more flexible connecting lead between controller and motor. I through personal preference fit multi way connectors each end so on the motor I am using a USB set up and a 4 way locking plug and socket on the front panel. Added refinement will be some sort of unit name and Steve's name although the number of strangers who will see it is not going to be less than the number of fingers on one hand.
Time to 'fire up' the soldering iron again to fit suitable plug to the controller end of the lead.
John. (hoping the supposedly pictures actually get attached)
PS Got a nice wooden case with locking catches it will all fit inside as well.

[miljnor]

You've been staring at it for a long time ,we are just now seeing it....looks awesome!

very nicely done!

[kwackers]

Steve,

Is there any chance this 16 bit number will be increased to 32 bit in the very near future?

Arvid

Hi Arvid,
I've had a quick look at the code, basically the value is 32 bits already - just that I clamp it at 16.
The issue is the internal maths would overflow if it wasn't clamped. For example to do the integer maths to convert to degrees requires the following:-
degrees = (curPosition * 36000) / stepsPerCycle.

The issue there is curPosition is the same size has steps per cycle and 36000 is a 16 bit number. So if curPos & steps were made 17 bits to allow microstepping I'd need to increase the maths in a number of places to at least 40bits - or use floating point.
It's doable - but it's not trivial...

Cheers,
Steve.

[ian j]

Hi all.
I've been following this build from the beginning with great interest, and after seeing Craynerd's build on maddmoder I took the plunge to build one.I've never etched a PCB before but using the OHP film method I produced a very good board at the first attempt ( just lucky?? I etched a second PCB to just see, & this one was as good) The rotary table had allready been fitted with a stepper motor for use with MACH 3 on my CNC emco mill. But this controller is so use full as a stand alone devider.
Thanks to Steve & Chris for sharing this great device.

[aarggh]

How typical, after looking at CNC rotary indexers on the web, I found there was already a thread on the zone with code!

Looks like another project to run concurrently! Thanks for making the code and detailed info available.

cheers,
Ian

[microstep1]

hi

Im starting to build the divider ,but for 2pieces i dont now wat i need
-the part ic1 18F452 (is it PIC18f4520 i/p )is the software inclus if buy new?

i wille thanks the inventer for schare it

[lucas]

The original firmware was written for a PIC18F452, there's a new one for the PIC18F4520

You will need to program the PIC with the correct firmware.
I see you are from Belgium: me too. I have 2pcs of the 452 and could eventually program them if you have problems with it.
Send me a PM if you're interested.

[chalks]

Hi all,
I am building this most desirable project using Lucas's layout and the original Steve programming.

Proggramming the PIC is proving a real headache. I'm trying to use a std desktop computer without serial port with a cheap USB- serial port converter,along with a e-bay type JDM programmer, and winpic 800.

Problem- The software driving the USB converter locates itself on port 6.the winpic program only locates itself on port 3.(seem to be a windows restriction). In short I need to get the converter driver over to port 3 and have not been able to find out how.

Anybody able to help?

Regards to all, chalks.

[microstep1]

hello

Lucas was very hulpfull,now I have 2 pieces of the pic +software inclus
thanks a lot for it:banana:

[Marty_Escarcega]

A friend of mine can and has burned the chips. $15 plus the cost of the PIC (newer chip), or you can supply the chip. PM me directly and I can put you in touch with each other.

Marty
Mesa, AZ

[chalks]

Hi Marty, thanks for your very kind offer of help.I am located in UK, In making this project the making is an important aspect for me, ie i only want to buy in parts that are not able to be made by me, the programming of the pic should be straight foreward, but somehow has beaten me so far.

Again thanks for your offer. Can anybody else offer suggestions for progress.
My thoughts on ubs port for example, do the converter driver titled as port6
and winpic have to be assigned the same port number to allow programming?

TIA.

Regards, chalks.

[lucas]

Yes the ports must match, a lot of software has problems with those USB to comm converters.
There are 2 solutions IMO:
- try to get a PC with a real comm port, beg a friend, borrow one or do yourself a favor and buy an old one, I have several of these old ones with real ports, dedicated for this kind of stuff, also communication with motor drives etc...
- try anoyher software, have a look here: PICPgm | A free and simple PIC Development Programmer Software for Windows and Linux
I had problems also with my DIY programmer hardware but this soft works perfect.

Hope this helps.

[chalks]

lucas, many thanks for you fast response to my problem. Your confirmation on the port matter is reassuring(I am not an electronic bod) and need all the help I can get.

I think I'll try the beg / borrow route on an older box first, your other suggestion looks scary to me!!

Regards chalks.

[lucas]

Scary? why??

you just have to use PICPgm iso Winpic with your current hardware setup to program the PIC.
I think it will solve your problems.

[chalks]

Lucas, thanks for the lead and assurance. I loaded the programme you suggested and the screen looks simple and I feel encouraged however i'm still left with the usb converter on port 6 and the PICPgm cant find it!

The fun continues.

Regards chalks.

[lucas]

Well, as long as you consider problems as fun

Back to option one then: Pc with real ports.
But I would suggest to keep the PICPgm soft, it was the only one that worked for me. And no, I don't have shares there...

[paul2]

Hi Chalks,

I had the same sort of problems. Even ruined and old, but favoured laptop in the process, using the parallel port with a very cheap programmer. Many of my problems I put down to old age and lack of knowledge. The answer in my case was to buy a PICKIT 2 clone on ebay for around £10. From that point on things became a lot simpler. Have a look at:
PICKIT 2 & MCU Universal ZIF socket for PICkit 2 or 3 | eBay
Or just look for PICKIT 2.
Like you, I wanted to do everything myself. In my case to learn a little more about PICs. However, I would be happy to send you a programed PIC or program your PIC, if it helps. I am in Lincolnshire, UK. No charge for the programing. Have you decided yet what you going to use to drive your stepper. If you have not and only need to drive a smallish, up to 2A stepper, have you seen these: Pololu/StepStick Stepper Motor Driver
Pololu/StepStick Stepper Motor Driver (RepRap RAMPS/Sanguinololu) | eBay
Or, if you are determined to build your own: Stepper driver kit, L298, L297
Stepper driver kit, L298, L297, + all parts as recommended for LONG LIFE stepper | eBay

Does anyone know what has happened to Kwackers web site, it seems to have been taken down? Gone for some time now.

Paul.