Re: [CAD_CAM_EDM_DRO] PIC Talk, was Chopper max voltage
Posted by
Chris Hellyar
on 2000-10-06 15:58:16 UTC
Hurro.
You're right about it being ambitious, it was about my third project with
the PIC, took ages to code, and then it only worked just OK. With two
servos unipolar chopper driven.. It was never fast though, and the analogue
side was a bit silly as well, I used four sense resistors, one for each
phase. I believe it's still being used though, I gave it to a chap who
wanted to move a telescope with it.. The max step rate was only in the
order of 500 steps/sec, and it glitched the step outputs when receiving
serial data (surprise). The only good feature was you could just send a
position (it kept a 32bit counter for each stepper) and forget about it.. A
more modern pic (71 etc) would be able to do it fine, as they have the async
port built in, and the chopper could be interrupt driven.
I have used the parallax ASM, your right, it is easier, but I found that I
could code that wee bit more efficiently in the Arizona opcodes for some
projects I've done recently, so I've standardised on it. I use the set of
macros from the microchip site for MPASM that allow using the parallax
source code though, as I have some products that are still written in it,
and I can just edit the header if I need to make a change.
Cheers, Chris.
* Design engineer, Assembly worker, Cleaner.
* Ohmark Electronics. PO Box 5302, Christchurch, New Zealand.
* http://www.ohmark.co.nz
You're right about it being ambitious, it was about my third project with
the PIC, took ages to code, and then it only worked just OK. With two
servos unipolar chopper driven.. It was never fast though, and the analogue
side was a bit silly as well, I used four sense resistors, one for each
phase. I believe it's still being used though, I gave it to a chap who
wanted to move a telescope with it.. The max step rate was only in the
order of 500 steps/sec, and it glitched the step outputs when receiving
serial data (surprise). The only good feature was you could just send a
position (it kept a 32bit counter for each stepper) and forget about it.. A
more modern pic (71 etc) would be able to do it fine, as they have the async
port built in, and the chopper could be interrupt driven.
I have used the parallax ASM, your right, it is easier, but I found that I
could code that wee bit more efficiently in the Arizona opcodes for some
projects I've done recently, so I've standardised on it. I use the set of
macros from the microchip site for MPASM that allow using the parallax
source code though, as I have some products that are still written in it,
and I can just edit the header if I need to make a change.
Cheers, Chris.
* Design engineer, Assembly worker, Cleaner.
* Ohmark Electronics. PO Box 5302, Christchurch, New Zealand.
* http://www.ohmark.co.nz
> On 6 Oct, Chris Hellyar wrote:all
> > Hi-ho,
> >
> > Yup, the PIC should be able to hose it doing that task, but I stacked
> > the ods against myself, as I was using a basic complier, and trying toget
> > two steppers driven off one PIC54, with a bit bashed serial portI'm
> > interface... Since then I've dumped the basic and use assembler, and
> > sure I could do it with time to spare..with
> >
> > We all live and learn. I think that was the last project I attempted
> > the basic complier, it was also the first time critical one I did, thatwere
> > a few years ago now..
>
> Boy, I understand the desire to use ANYTHING except that PIC assembly
> language. My solution, a long time ago, was to use Parallax assembly
> language. If you're not familiar with it, it's kinda like a superset
> of Intel 8051 language, meaning it's easy to write AND easy to
> understand after you've written it. And it takes no more instructions
> than Microchip assembly to do anything - it's exactly the same
> efficiency, just WAY easier to code in.
>
> As far as your project was concerned, that's damned ambitious; two
> motors driven serially. I was assuming one motor driven via step and
> direction. Man, amazing what a 30 year old TV remote control chip can
> do !
>
> Alan
>
> --
>
> Alan Rothenbush | The Spartans do not ask the number of the
> Academic Computing Services | enemy, only where they are.
> Simon Fraser University |
> Burnaby, B.C., Canada | Agix of Sparta
>
>
>
>