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RM57L843: Emulating LM629 full positioning PID's

Petric Zeljko
Prodigy 90 points
Part Number: RM57L843
Other Parts Discussed in Thread: LM629, LAUNCHXL2-RM57L, MOTORWARE, HALCOGEN

Some 12 years ago I used venerable LM629 with C8051F043 and isolated CAN2, mosfet H bridge to position low mech. time constan,t ironless capstan brushed DC motor.

Having LAUNCHXL2-RM57L and DRV8432 now, my questions are;

1) Can I fully emulate pair of LM629's full position PID's  with RM57L resources ?

2) If so, what would be estimated positioning loops frequency?

3) To old to waste remaining R&D resources in reinventing the wheel, is there full positioning PID sample code in TI Motorware or HALCOGEN for RM57L, LM629 style ?

4) since LM629 is still in TI listed product line, shall such RM57 setup outperform it  ?

Positioning PID loops shall do, dual optical A/B encoder inputs and sign/magnitude outputs are worth rethinking then.

Cheers,

Petric

  • 0
    TI__Guru**** 190686 points

    Hello Petric,

    I am not familiar with LM69 device. I will checked its datasheet, then come back to you.

  • 0 in reply to QJ Wang
    Prodigy 90 points

        Coming from TI_Guru, misreading TI component LM629 mentioned several times in questions above, sounds strange at least.

        I'm to old for such an answer, whatever it may be, so I'd rather rephrase my questions;

          Since LM629 was initially designed by National Semiconductor, the ones I used decade ago, its datasheet takes time to analyse, and a bit of nightmare to implement interfacing it to the master uC.    Back in '97, Microchp boasted it can emulate LM629 with its PIC uC and taking that, RM57L should be running circles around pair of independent LM629's.

        No need to dive into LM629 datasheet, nor to look for LM69.

        For someone 4 decades in embedded world, nothing is as simple as it seems, non taken for granted.

    ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------

     1) Can RM57l run TWO independent positional FULL PID loops, A/B optical encoders as RT inputs and PWM  outputs ?

    2) If so, would those PID loops be faster compared to pair of dedicated 8MHz LM629 processors running in parallel ?

    3) Since my emphasis is on FULL positional PID, not PI, is there TI sample code about positional PID applicable to   RM57L ?

    With respect,

    Petric

  • 0 in reply to Petric Zeljko
    TI__Guru**** 190686 points

    Hello Petric,

    Apologies for late response. I am not familiar to the PID loop. The example of our motorware supports PID loop control. The CMSIS also contains PID control function:

    www.ti.com/.../HERCULES-DSPLIB

    software-dl.ti.com/.../Examples.html