• State TI Thinks Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 1 answer
  • Subscribers 46 subscribers
  • Views 156 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ADS1235: Digital filtering and Different measurement rate

Abinaya
Prodigy 90 points
Part Number: ADS1235

Tool/software:

Hello Team,

I'm working on ADC_ADS1235 with AM243x_LP.

I am now making use of the mode0 registers to change the digital filtering and measurement rate.

Our clients' specific requirements have different measurement rates of up to 2400 samples per second and cut-off frequencies of 1, 2, 5, 10, 20, 40, 80, and 150. The default cutoff frequency is 50 & 60 Hz.

In this case, I need to create the digital filter algorithm. Could you suggest an implementation guide for this ADC?

Also, the ADS1235 FIR filter has a maximum data rate of 20 samples. Is it feasible to measure 2400 samples?

How to find the different cutoff frequency coefficients in FIR.

Thanks,

Abinaya 

  • 0
    TI__Mastermind 40021 points

    Hi Abinaya,

    The digital filter cutoff frequencies are give in Table 4, which I have copied below

    As you noted, the FIR filter is only offered at data rates of 2.5, 5, 10, and 20 SPS. You can use the Sinc filters for faster data rates and/or higher cutoff frequencies

    -Bryan

  • 0 in reply to Bryan Lizon86
    Prodigy 90 points

    Hi Bryan,


    Thank you for the response.

    If I use a Sinc filter for 2400sps with different cut off frequencies, how do I design an algorithm based on those requirements?

    Regards,

    Abinaya

  • 0 in reply to Abinaya
    TI__Mastermind 40021 points

    Hi Abinaya,

    The ADC does not natively support different cutoff frequencies other than what is shown in Table 4

    If you want additional filtering, you will need to design your own digital filters in software. I don't have any examples of how to do this, but this should be a relatively trivial effort in Matlab. Or you can google "digital filter xxxx", where "xxxx" is your desired coding language. I tried this with "python" and got a few results that looked promising

    -Bryan

  • 0 in reply to Bryan Lizon86
    Prodigy 90 points

    Hi Bryan,

    Thank you for the information.

    But we implemented the digital filter algorithm in C code. Is it possible to share this Python code?

    Thanks again for the guidance!

    Regards,

    Abinaya

  • 0 in reply to Abinaya
    TI__Mastermind 40021 points

    Hi Abinaya,

    As mentioned, I don't have any code to share. I recommended searching the internet because digital filter code is fairly common and easy to find

    But I don't have any specific links, etc., to share with you.

    -Bryan