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How to configure 40 PWM outputs

Richard Dualmann
Intellectual 560 points


In the website:

http://www.ti.com/lsds/ti/microcontroller/tiva_arm_cortex/c_series/tm4c_arm_cortex-m4/overview.page

 Tiva C Series MCUs have the key features:
 Advanced motion control capability—up to 40 PWM outputs.

My problem is how to configure this key feature into a real motor controller(12-phase SR motor)?

Strangely, in the document "spmt285a.pdf", there are 16-channel PWM outputs only, not 40 outputs.

Thanks.

  • 0
    Guru 117855 points

    Our group works w/many ARM MCUs - multiple vendors - and nowhere have we encountered 40 "true-blue" PWM Outputs.

    However - that 40 figure does resolve/justify.  There are 16, "PWM Generator" channels - and 12 general purpose Timers - which usually may be configured as, "split-pairs," - thus satisfying the 40 figure stated. 

    While not, "full-fledged" PWM Generators - Timers configured as PWM Outputs are faster/simpler to set-up/configure - and do provide reasonable performance. 

    The PWM Generators enable advanced fault detection - which may yield a "near-automatic (i.e. w/out SW intervention)" PWM cessation with full/proper PWM output recovery - once the fault clears.  (ideal for transient faults - which often "self-clear" - especially when the PWM output halts)

    Target application - and your design goals - in concert - dictate the requirement for the "true" PWM Generators... 

  • 0 in reply to cb1_mobile
    Intellectual 560 points

    My application is one 12-phase SR Motor (16/12 pole, 50kW)and 12-phase boost converter integration.

    Here need 12-channel A+B PWM independent singals for a 12-phase SR Motor and 12-channel (low-side) PWM independent singals for  12-phase boost converter.

    Has any example code I can read it in detail?

    Thanks.

     

  • 0 in reply to Richard Dualmann
    Guru 117855 points

    Thank you - kindness of, "Verify" always welcome/appreciated.

    It would appear that 3 (of 4 total) independent PWM Generators w/in these MCUs may satisfy your 12-channel, A+B PWM requirement.  (devil - as always - lurks in fine details - absent here)

    Remaining 12-channel PWM signals may be sourced from 6 Timers - operated as, "split-pair" - and config'ed as PWM Outputs.

    Suspect that you'd benefit from past, BLDC, BDC, ACIM motor projects all woven w/in past StellarisWare.  (possibly w/in rebrand area - although we do not know - nor use - this early development)  Much technical detail & code exists w/in the 3 motor areas referenced above...