Need Help!- PICStep/Linistepper/AVRSTMD Code in C or BASIC

[joprinz]

Hello Everyone,

I have read soo many posts and discussions about the PIC Step driver , Linistepper as well as the AVRSTMD driver. Thanks to their respective designers it is possible for many hobby CNC builders like me to design a driver quickly. But I have seen... as we learn more the more complex we would like our machines to be.

For instance I wish to add some features like idle current reduction or increase the current rating of the drivers by upgrading the Transistor stage. But all these would require a certain amount of change in the PIC/AVR code. And that is where my problem starts. All of the Drivers mentioned above are open-source and hence the Assembly code file is available freely. I have read the Microchip App Notes on "Microstepping Driver" code but even they only provide the ASM File not the C Code file. I am capable of writing/Modifying C or Basic Code for PIC and AVR but I am not soo good at Assembly code. It would be a lot easier for me to build a driver if I can obtain a tested code rather than trying to "reinvent the wheel"

I was wondering if someone can help me with a Stepper Driver Firmware code in C or BASIC which has PWM Current Control and Microstepping. I am willing to do the Circuit design complete with PCB Design files, part list and Drive Performance results on various motors and step modes. We could even make this an Open-source project if there is considerable interest.

Please Advice!

Regards,

Joe!

[James Newton]

I would love to have C code for an open source controller, even the Linistepper, for which I sell the kit and add-ons:
http://www.piclist.com/techref/io/st...step/index.htm

Ide current reduction can be accomplished in the Linistepper with a diode, cap, and resister as long as the step signal from the PC returns to ground between steps. See:
http://www.piclist.com/techref/io/st...axis3build.htm under "Options" / "Auto low power" near the bottom of the page. Granted, it would better be accomplished with code in the PIC, but this would require that the PIC be setup with a timer interrupt, time count, and external crystal. These are non-trivial changes. And the PIC used is close to being out of code space as it is, so you will have to upgrade to the next version if you do find or write C code.

I'm not sure I understand why the code would need to be changed to upgrade the power transistors used... You can find higher power versions and just substitute them. Honestly however, the hardware design of the Linistepper will provide diminishing returns at very high amperages, so there isn't much point. If you need that sort of power. Pony up for a Gecko. There just aren't any open source designs that are anywhere near as good for high power controllers. The Linistepper will perform just about as good as a Gecko at the medium to low power range, but it doesn't scale up.

Best wishes.


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James.

[joprinz]

Thank You James for your reply.

I had built Linistepper for my first router project (I run it at 2A per phase. But It did not have current reduction. I will add it as per your design)One thing about Linistepper is that it is indeed a really well designed driver and sometimes I wish it could do higher currents.

From your reply and also from what i have read at the linistepper site I understand that going above 5A is not preferred for Linistepper. However of-late NEMA 34 sized steppers are available at really reasonable prices and that makes a driver that can do above 5A a REAL WISH.

I have been trying to build a stable driver which can do 6A preferably in Bipolar mode. But since this is more of a private hobby for me I find it hard to find the time to design a driver ground up. I was hoping if I could get the Source code for say the PIC Step or the AVR-STMD may be I could alter the code and use a Discrete FET Bridges instead of the LMD Series (The LMDs are really good chips but they have a 3A Max Limit).

Please Advice!

Regards,

Joe!

[James Newton]

I totally agree, an open source driver that could really do a good job with those nice big motors would be great. I hope you find one or make one, and please let us know.

From what I have seen, the design of a high power stepper driver that doesn't have all the standard resonance and other problems requires a lifetime of experience in the area. The subset of people who have that level of experience and who are willing to do open source is currently... zero. Maybe that will change.

Best wishes.

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James.