🚀 go-pugleaf

In article <3301@csccat.UUCP> jack@csccat.UUCP (Jack Hudler) writes:
>In article <2968@ccnysci.UUCP> jhuang@ccnysci.UUCP (Jian Huang) writes:
>>I am looking for a stepper control chip. There are some
>>good chips for DC motor such as National LM628, but only a
>>few step motor control chips which can not meet my
>>requirement: 100k pulse rate, changing parameters
>>(speed, target position) on the fly. I would appreciate if
>>anyone can give me some help.
>
>100k pulse rate into a 200 step motor would yield 500 rps, unless you
>intend to use microstepping translators you could not attain such 
>high rate of speed from steppers. 
>However I assume you are using micro-steppers. 
>If you are using micro-steppers then you know the cost of doing so,
>so you could spend some more and buy an indexer that would meet your
>needs, after all they spent big bucks developing stepper controllers,
>why re-invent the wheel?
>I have use one from Compu-Motor, it's the PC23 (for IBM PC/XT-AT),
>it can produce 500k pps and with 3 axes,encoders,joy stick and limit
>switchs, all for $2000. 
>
>Hmmm.. changing speed and target on the fly.... sounds like your trying
>to control a telescope.. :-)
>-- 
>Jack 		Computer Support Corportion		Dallas,Texas 
>Hudler		UUCP: {texsun,texbell,attctc}!csccat!jack


That's what I thought, too. Jiang, why don't you tell us the application? I
cannot answer your question about a controller chip, but daisy-wheel
printers use fairly highspeed steppers for printwheel and carriage motion as
well as the platen indexing. Not 500 rps, but pretty quick, and at least in
the case of printwheel positioning, they have a similar requirement to yours
regarding changing parameters on the fly. As soon as a character is printed,
the motor has to move to a new one by the quickest route. As I recall, (it's
been almost 6 years since I worked with these things), both Qume and Diablo
printers used discrete control logic, but when Ricoh entered the market, they
used an 8085 to control all printer functions. If your requirements are as
stringent as they seem, maybe a microprocessor is really what you're looking
for.


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