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Highest ADC sampling speed for TMS320F28069

Yang Wang1
Prodigy 20 points

Other Parts Discussed in Thread: TMS320F28069

Hi, Could you help to check the max sampling frequency of TMS320F28069 when at least two A2D channels work simultaneously. I plan to use it for ultrasonic testing which requires up to a few MHz sampling rate with multiple A2D channels. Do you have any other MCUs supporting faster ADC sampling speed? Thanks

  • 0
    TI__Genius 17121 points

    The F28069 ADC sample rate is 3.46MSPS, two channels can be sampled at half that.  If faster sampling is required I suggest the Delfino family F2833x in which the ADC samples at 12.5MSPS and likewise 2 channels can be sampled at half that rate.

  • 0 in reply to Joe Prushing
    Prodigy 20 points

    Hi,

    I'm trying to get the highest sample rate with the F28069 but just got 400 kSPS.

    The ADC module is configured in Continous Mode with EOC as Interrupt source and, the same Interrupt, as trigger of SOC

    The main clock is 90 MHz.
    The ADC clock is 45 MHz
    The sample window is 7 ADCclock cicles (ACQPS=6)

    In the ISR just toggle an GPIO to watch a half of sample rate with an oscilloscope.

    The code is executing from the FLASH memory.

    Please, could you help me to improve the sample rate?

  • 0 in reply to Luis Guzman
    TI__Guru 60865 points
    Hi Luis,

    If you use all 16 SOCs and trigger an interrupt every 8 conversions, you will have approximately (8/3.46MSPS) = 2.312us to get in and out of the interrupt, toggle the GPIO, and collect all the data. This is 2312ns * (1 / 90MHz) = 208 CPU cycles, which is probably doable, but will take most of the CPU bandwidth. If you enter the ISR after every sample you won't have enough time.

    You may also want to run from RAM or use the DMA to collect the ADC samples.