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1733Re: [rsa] BS2, Vantec RDFR21, DC Motor ?

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  • Camp Peavy
    Jun 20, 2005
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      On "Rusty" I'm driving two RC car ESC's (Novak XRS's) with a BS2 and Mini Serial Servo Controller (MSSC) <http://www.camppeavy.com/rusty.jpg>.


      ESC's take commands just like servos. Have you used the Stamp to move a plain servo yet? If it works with a plain servo it should work with the ESC. ESC's just like servos are looking for pulses between 1 and 2 milliseconds (ms); 1-ms for one direction, 2-ms for the other and ~1.5-ms to stop. If you drive it directly from the BS2 you'll use the "pulsout" command. Pulsout 500 for one direction and 1000 for the other. The BS2's pulsout command runs at 2 micro-second (1/1,000,000/sec) units so 500 x 2 micro-seconds = 1 millisecond (1/1,000/sec) and 1000 x 2 micro-seconds = 2 milliseconds. The "stop" value should be 750 but it usually ranges between 730 and 770.


      Once you get it going you might want to seriously consider off-loading the pulsing to a peripheral board like the MSSC otherwise your Stamp might be too busy to do anything else. With the MSSC your Stamp simply gives it a value between 0 and 254 and goes back to more important things. The peripheral board does the pulsing.


      One of the tricks with the Novak XRS is you had to put it in the "stop" position before changing directions. They call this “Smart Braking II”. I implemented it through a “gosub” routine.


      Good luck and keep us posted.




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