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micropar

Fresh Boarder 		Click here to see the profile of this user

2007/07/20 09:58

Why 2 QEI interface on 6965 ?

Hi all,

I don't understand:
1) Why 2 QEI interface has been provided on LM3S6965?
2) What is the use of 2 QEI when there is provision for only 3 pairs of PWM suitable for only one 3 phase motor switching?

I suppose, instead of 2 QEI, Luminary should provide CAN interface and 4 pair of PWM suitable for Bipolar Stepper motor, directly driving (off-course, using suitable MOSFET drivers).

Regards,
--micropar--

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mpanetta

Senior Boarder 		Click here to see the profile of this user

2007/08/23 08:00

Re:Why 2 QEI interface on 6965 ?

Why not 2 QEI? I love it. It means you can drive up to 2 brushed DC motors with feedback. Just because you have 6 PWM's does not mean you have to use all 6 for a BLDC or PMSM. 4 PWM's would be plenty for 2 brushed DC motors and thats exactly what I plan on using this chip for.

Another thing 2 QEI's could be used for is electronic gearing. One could be an input from another shaft and the other could connect to the BLDC motor. The firmware on the controller would take the input shaft encoder and divide (or multiply) the number of turns by some arbitrary number and use that to set the speed/revs of the BLDC motor just like a gear box (but done in software).

There are many many things 2 QEIs could be used for, and I for one would love to see more parts with 2 QEI's (and even more pwms!) :)

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