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TMS320F28335-Q1: Need help choosing a DSP chip please

Eric Norton
Prodigy 70 points
Part Number: TMS320F28335-Q1

Tool/software:

Hi All, 

 I have a particular issue and wonder if a DSP chip would solve it. I currently use an ARM Cortex M4F running at 192 MHz and while it works, I am still not very happy with the top-end performance. I am running a custom firmware that converts the gcode to motion for a C02 laser or CNC machine. Since the firmware uses a lot of math functions (single precision floating point) sqrt, sin, cos, abs, floor, ceil, trunc, etc.. will a DSP chip be able to process this data much faster to achieve the higher speed I am looking for? I have never used a DSP chip before and the reason I am asking these questions. I don't want to assume anything and go buy a board, programmer, and all the equipment and then find out I spent money on something that might not do what I want it to do. Will a DSP chip work for this type of application and how will I benefit from it? If it will work what are the benefits compared to an ARM chip?

I am thinking of getting the TMS320F28335-Q1 but open to using something more aligned with the motion control application. I need something with FLASH, high SRAM (160K+), needs to have I2C, UART, PWM, 32-bit timers, etc...

Can someone help me out with this, please?

Thanks,

Eric Norton

  • 0
    TI__Guru** 119360 points

    Eric,

    Yes, F28x devices are often used exactly for these type of applications 

    Is there a reason you selected Q1 version?  These are for automotive and not required for industrial.

    If you want to be on the latest platform I would recommend looking at 

    TMS320F28P650DK data sheet, product information and support | TI.com 

    and you can start development with a low cost EVM to do evaluation. 

    LAUNCHXL-F28P65X Evaluation board | TI.com

    some application notes on benchmarking / accelerators 

    https://www.ti.com/lit/spracw5 

    https://www.ti.com/lit/spry288 

  • 0 in reply to ChrisClearman
    Prodigy 70 points

    Hi Chris,

     I just selected the part not knowing if it was automotive or not. Is there a board with the same or similar chip in the QFP version? I shy away from BGAs because they are almost impossible to solder without the right equipment. I have a reflow oven but typically the ball pitch is a problem for me and the board price goes up for the tighter pitch BGAs. Please let me know if there is a single core chip and launchpad eval board. I need the highest possible SRAM and at least 200 MHz speed with 128K or more onboard flash.

    Thanks,

    Eric Norton

  • 0 in reply to Eric Norton
    TI__Guru** 119360 points

    Eric,

    there are single core versions of this device with QFP options, but they share the same dual core version of EVM. When you do a project just select the S version and it will run as single CPU.

    TMS320F28P650SK data sheet, product information and support | TI.com

    If you are uncomfortable with that, see the latest single CPU (with accelerators and // CLA processor option) device

    TMS320F28P550SJ data sheet, product information and support | TI.com

  • 0 in reply to ChrisClearman
    Prodigy 70 points

    Hi Chris,

     Ah okay, I see your point now. I am used to the ARM series of microcontrollers. Is DSP programming a lot different or similar to ARM? How hard would it be for me to get up to speed with DSP? In terms of overall performance, how much faster would the DSP be compared to an ARM Cortex M4F with floating point enabled? I know that sounds a bit general but I am looking for strong points to consider using the DSP vs the ARM chip. The firmware is similar to GRBL which is a gcode interpreter just a completely custom version of it. The firmware as it stands now for the ARM chip runs pretty fast but needs more processing power to handle the math functions which I think the FPU might be slowing things down a bit and causing the motors to lag/slow down during high data rates. If you think the DSP will accel at all of this please let me know and I will get the DSP board and try it out.

    Thanks,

    Eric Norton

  • +1 in reply to Eric Norton
    TI__Guru** 119360 points

    Eric,

    In a control loop application, the whitepaper I mentioned above basically summarizes that a 28x is effectively 2x the performance of an M4F.  So a 200 MHz 28x would require a 400 MHz M4F/M7 for similar performance.

    In most DSP processing it is typically about the same, with some areas even being stronger for the 28x. 

    I think it's worth the small investment to purchase the launchpad linked above and do some testing of your own

  • 0 in reply to ChrisClearman
    Prodigy 70 points

    Hi Chris,

     Okay excellent and it's the news I was hoping to hear Slight smile. Thank you very much for your help and I'll get one on order. 

    Thanks,

    Eric Norton