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  • TI Thinks Resolved

ADS1298ECGFE-PDK: ADS1298 Sampling rate

Part Number: ADS1298ECGFE-PDK

The sampling of ads1298 is not accurate.

I set HR mode and 1k SPS at CONFIG1 but, measured about 930 /sec on a PC.

when I changed register 1k SPS to 500 SPS, it was measured about 420/sec.

What are the factors that can affect the sampling rate?

  • Hi Dongjun,

    The sample rate of the ADS1298 is related to the clock source. Are you using the internal clock of the ADS1298 or the external clock source found on the ADS1298ECGFE-PDK? Please refer to section 5.2 (pg 42) of the users guide for more details: www.ti.com/.../sbau171d.pdf

     

    Regards,

    Tom

  • In reply to Tom Hendrick:

    Thank you for your answers.

    and , I am using the internal clock, and the JP pin is also properly connected.

    This figure is marked when DRDY falls from high to low.

    As you see, The waveform is visible in 1ms, but it is cut off in the middle.

     I don't know what is matter

  • In reply to Dongjun Lim:

    Hi Dongjun,

    Are you using the complete ADS1298ECGFE-PDK kit or have you connected in your own controller? If all you are doing is configuring the chip and monitoring DRDY, the signal should remain consistent. Make sure you are not toggling the PWDN pin or sending any commands to the device through the SPI interface.

     

    Regards,

    Tom

  • In reply to Tom Hendrick:

    Hi Tom,

    I am trying to receive data from a ADS1298ECGFE (removing the MMB0)  with Atmega16 microcontroller.

    The problems start to happen when using the RDATAC mode.

    I used interrupt that is triggered on the falling edge of the DRDY signal. (1000 SPS)

    In the figure below, When DRDY remains LOW for 5ms, the data receive command can not be sent.

    Blue Line = MOSI pin

    Yellow Line = DRDY pin

  • In reply to Dongjun Lim:

    Hi Dongjun,

    I'm curious, but did you see the same break in the DRDY output when you were using the original setup with our MMB0?

     

    Regards,

    Tom

  • In reply to Tom Hendrick:

    Hi, I am Dongjun.

    I did not use MMB0.

    and I solved the problem of the DRDY signal. The cause was a delay reading the DRDY signal.

    As a result, I confirmed that I read about 1004 data per second.

    I measured data for 1 sec and 1 min using a 16-bit timer, but I could not read exactly 1000 SPS.

    How do I get exactly 1000 data per second.

    please help me.

  • In reply to Dongjun Lim:

    Hi Dongjun,

    Sorry for the delay - you would need to use an accurate clock source to get exactly 1000SPS.

     

    Regards,

    Tom

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