Microcontroller for VFD

[ali50]

Hello friends. I'm starting to build a VFD prototype. I was wondering if any of you has ever worked with a particular mcu/dsp that you particularly enjoyed working with and would recommend. I know microchip and motorolla and TI have good products to use for motor control. I personally prefer motorola mc68's over the PICs but you can't deny the fact that microchip is alot better and more user friendly with their documentation and it is easier to find your way around in microchip. This might be the reason I'm going with microchip, but if I'm missing out a lot by not using motorola or TI microcontrollers, let me know.

Thanks.

 

[JPetersen]

Hi,
Check out Analog Devices - ADMC401
is prepared for motor control applications.

 

[ali50]

Thank you.

 

[buzzp]

The one you may have overlooked is ATMEL. In comparison to PIC chips they are about 4 times faster and also have built in math functions. The programming is even a little more straightforward than PICs. Have not used any to make a VFD but have used both mfg's for A/D converters.

 

[skills]

Ditto on the Atmel, I would recommend the ATMEGA8535, it has 8 channels of 10-bit A/D, and many peripherals. I use AVRBasic compiler to write for it. The Basic is fast and compact and gives about as much control as C. You can also write inline assembly and the compiler handles it great. These are much more straightforward than Microchip in my personal experience, plus they do more and work faster. I don't see why I wouldn't use one to make an Inverter, I'm sure they are used in them now!

 

[skills]

Hey, oops, corection and head skip!!! I use BASCOM as the Basic compiler. I have used AVRBASIC; but, BASCOM is more usable in my shop.

 

[buzzp]

I program ATMEL in assembly. If you program PICs in assembly now I think you will prefer ATMELs assembly over PICs once you get used to it. Have not used any C or basic compilers with either one.

 

[itsmoked]

Man.. I could never go back to assembly! Good compilers do just as well, but super charge your productivity. The program I am finishing up is 4,100 lines of C that run on a PIC18F252. It couldn't have been done in assembly in 4 times the time.

The PICS have more memory and you can hit 500ksps at 10bits (A/D) as compaired to ATMELs 77khz which may help in your motor control. Higher rates let you do derivatives for control.

Check out the dsPIC30F6015.

 

[buzzp]

I just got used to assembly and would venture to say that if I programmed in C it would take 4 times longer than assembly. I guess it all depends on what your used too.
Complexity does not necessarily constitute C code, depends on your programmer (person-not hardware).

 

[cbarn24050]

Hi itsmoked, ive just started with that processor, are you saying you got 4100 C instructions into this device?

 

[itsmoked]

buzzp; Sorry I didn't understand your last line.

I use C a lot like assembly.. I use maybe 20 different "C" instructons and avoid the "pointers pointing to pointers of address arrays" kinda stuff. buzzp you have the "longer" right on the first time, for-shore, because of the hassles of setting up your compiler and libraries etc., etc.

cbarn24050; Hello, No, no, I have those 4,100 lines crammed into the 18F252 which only has 16K words(32k bytes) of space. This is 82% of code space (91% with printf on supporting my longs(4bytes) and double floats(32bits).

I am using the Hi-Tech compiler which really does a great job of cramming. They have supported me well to. "Hey is this a compiler bug?" Yes sir..sorry sir.. please download the fixed version..They do this quickly too.

But back to your space question cbarn, doesn't the 6015 have 66k of word space?? Seems like you could get at least 6-7k lines of code into it.. You may not want to, since VFD stuff needs speed more than space, I would guess.

 

[skills]

As far as needing lots of speed, let the H-bridge do the hard work and unload the processor from other things so that it can monitor the zero crossing on line and sync stuff and do higher level calculations such as V/Hz control. I assumed you were doing V/hz as opposed to Vector control which requires lots of trigonometry to be done. I have built motor inverters using the MPU to run just 6 transisters; but, today they have modules that are basically a drive on a chip that handles the real time low-end stuff great and offers better control of the e-mag stuff.

 

[cbarn24050]

Hi itsmoked, I think you got my question mixed up with someone else's. I thought the High Tech compiler was supposed to be bug free! I guess not, oh well keep with the assembly for now.

 

[ali50]

Yeah it is V/Hz control. Thank you all for your comments.

 

[itsmoked]

cbarn24050; There are NO bug free compilers..

 

[cbarn24050]

Hi itsmoked, thats a pretty big statement to make, in any event the bugs that might be there should not be easily spotted.