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C2000-DIGITAL-CONTROL-LIBRARY: High-Speed PID Control with TI Digital Control Library (DCL) on C2000: Achieving 5MHz Update Rate

Tuna Eren CINKAVUK
Prodigy 10 points
Part Number: C2000-DIGITAL-CONTROL-LIBRARY
Other Parts Discussed in Thread: C2000WARE

Tool/software:

I want to design a PID controller using Digital Control Library (DCL) functions. Our control loop update frequency must be at least 5 MHz. Can this speed be achieved using the PID functions in DCL? How many clock cycles do the PID functions require for computation? What is the maximum possible update frequency? Is there any documentation where I can find these details? Can you recommend a reference design for PID/PI control applications operating at 5 MHz or higher? Which C2000 processor is the most suitable for these applications?

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    TI__Intellectual 1720 points

    Hello Cinkav,

    I believe your options are pretty limited due to the frequency required for your design. Let me try to break down the question and answer them one-by-one.

    We provide the benchmark numbers of all DCL functions, please refer to section 1.5 of the DCL User's Guide, which can be found in our C2000Ware SDK's libraries\control\DCL\c28\docs folder. Please note that function coded with C like DCL_runPID_C4 are 32bit floating-point C/ASM function for CPU core, and with asm function running signaificantly faster than its C-source counterparts. Function coded with L is meant to be run on CLA core.

    Also refer to C2000 MCU Overview for the device profilio we offer. Our highest-clocked devices are F2837x and F2838x running at 200Mhz for both C28 CPU Core and CLA core, this means our control loop must be completed within 200Mhz/5Mhz = 40 cycles. Looking at the benchmark table, no PID functions are suitable to your design, only DCL_runPI_L1/L2 (PI controller in Series/Parallel configuration running in CLA core with 33/34 cycles) suffices. And furthermore, by offloading control loops to the CLA core, you can free up the CPU core for other tasks.

    So in summary, only PI controller running in CLA for F2837x and F2838x devices are suitable for your design. Please let me know if you have further questions, I would be happy to help!

    Best,

    Sen Wang