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About SPS in ADS1118

Jiwon Oh
Prodigy 60 points
Other Parts Discussed in Thread: ADS1118, ADS1118EVM

I asked about timing issue, I'll check it with native code for precise operation flow. (before I tested through Micro Framework)

 

Before that, I want to make sure the "SPS" option.

ADS1118 provides 8 types of SPS from 8/sec to 860/sec.

If I set the register as 8SPS, is it average datas in the period?

 

Like below,

Rate -> 8 : 860 = 1 : (about)107 & Assume that SPS860 data is expressed as data[#]

1st of SPS8's data = the average of data[0]~data[106]

2nd of SPS8's data = the average of data[107]~data[213]

3th of SPS8's data = the average of 107 data[214]~data[320]

...

 

Thanks, Jiwon.

 

  • 0
    Prodigy 60 points

    I attached result of lab test using ADS1118EVM.

    There is output difference between eash SPS options.

     

    <SPS860>

    <SPS32>

    <SPS8>

  • 0 in reply to Jiwon Oh
    TI__Guru 55466 points

    Hi Jiwon,

    The ADS1118 is a Delta Sigma converter providing different output data rate options from 8 SPS to 860 SPS.  Delta-Sigma converters perform the input signal sampling process at a higher frequency rate and are considered over-sampling converters. In the ADS1118, the modulator samples the inputs at approximately 250kHz during the conversion period and outputs a single conversion result digital code corresponding to the average over that period of time.  For example, when the ADS1118 is set up at an output data rate of 8SPS, it will sample the signal several times at 250kHz, and provide a single output code conversion corresponding to the average of the samples during the 0.125 s period (period of 8 SPS).

    Best Regards,

    Luis