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Save data

Luis Coimbra
Prodigy 140 points

Hi,

I'm using the TMDSPREX28335 with Code Composer Studio 4 and Simulink for code generation.

My question is how can I save the data being read by the ADC for an extended period of time and at the same  frequency of the data acquisition?

Thanks, 

Luis

  • 0
    TI__Guru 60865 points

    Luis,

    This depends on how fast the ADC is reading data and for how long.

    Each ADC sample will generate a 12-bits of data, usually each placed into a 16-bit word.  You can:

    *Sample and fill RAM until you run out of space.  You time will be limited to sampling for (sample rate * 16-bits) / (memory) seconds.

    *If you add an external memory using the XINTF module, you can increase the amount of sampling time by using the external memory, which will have more capacity.

    *If you want to indefinitely keep sampling, you will need to find a communications interface that can keep up with your ADC.  

    - At 12.5MSPS, the only option I think you have is the XINTF, as discussed above, which won't be able to store results indefinitely 

    - At lower frequencies, you may be able to use the SCI, SPI, I2C, McBSP, JTAG, etc to indefinitely scan your data out to a different processor, to a PC, or to a large memory (e.g. SD card).

  • 0 in reply to Devin Cottier
    Prodigy 140 points

    Thanks for the answer.

    My idea is to save a few seconds worth of data into a file on a PC at a frequency not lower than 1 kHz.

    What should I do?

  • 0 in reply to Luis Coimbra
    TI__Guru 60865 points

    Hi Luis,

    So 1KHz * 16-bits will give you a data rate of about 16Kbps.  I think you will be able to scan this out using the SCI module connected to the FTDI chip on the experimenter's kit.  This will convert the SCI messages into USB communications, which you can read on the PC (not sure how exactly in Simulink).  I think you can find more specifics on this method if you search around the forum a little bit.