I have an application where i'd want to use the 'quadrature encoder' on the PIC, especially since it has programmable filtering capabilities.
However, there are so many erratas with using the deadtime feature in their PWM modules that i'm sure to get some shoot-through.
Does anyone know if there are any Freescale (preferably M68HC09) parts that would be functionally equivalent to the PIC18F4431, i.e. have quadrature encoder pins, and enhanced PWM capabilities for motors?
Thanks, Mike
On 20 Jun 2005 10:09:37 -0700, snipped-for-privacy@yahoo.com wrote in comp.arch.embedded:
Can't speak about Freescale directly, but I imaging they have some parts that will do this in the 56K DSP series. There are also some HS12 parts with PWM, don't know about dead-band capacities.
TI has a whole series of 32-bit fixed point DSPs in the TMS320F28xx family that have timers that do quadrature decoding, including zeroing the count on an index pulse if you want. And they have very flexible PWMs with simple dead-band control.
Some of the newer parts are quite reasonably priced.
-- Jack Klein Home: http://JK-Technology.Com FAQs for comp.lang.c http://www.eskimo.com/~scs/C-faq/top.html comp.lang.c++ http://www.parashift.com/c++-faq-lite/alt.comp.lang.learn.c-c++ http://www.contrib.andrew.cmu.edu/~ajo/docs/FAQ-acllc.html
There are some 8-bit Freescale parts with very flexible PWM units for motor control. I think you'd have to use ordinary timer inputs for encoder inputs, however. But since the PWM unit does a lot of the work already, that should not be too much of a hardship unless you are running at very high speeds. Stepping up, there are 56k "hybrid" DSPs with everything you need for motor control. I haven't used them myself, but I've seen them demonstrated, and was impressed.
Thanks Jack and David!
yup, looks like the MC56XXX are what I should look into. There are a few specialized 18F pics to do some specialized motor functions as well as quad decoder interfaces as well, but like i said, i'd have to investigate if their latest erratas fix the deadtime injection problems. There's also the dSPIC, which seems to be equivalent to Freescale's 56K. Can't get into TI's parts, or else it would be a whole new learning curve!
Oh well, now i need to get either the Code Warrior compiler (56K), Hi-Tech compiler or free 60-day dSPIC compiler (dSPIC).
-Mike
Alex
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