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Compiler/TIDA-00378: TIDA-00378

Part Number: TIDA-00378

Tool/software: TI C/C++ Compiler

hello everybody,

I am building a sensor system using TIDA-00378.  But I don’t know the frequency range of the signal generated when the photodiode detects the scattered light.

And what is the reason that flow and fhigh are 0.44 HZ and 184.5HZ respectively in stage 1 filter.


  • Hi Boli,

    The frequency range will depend on the flow rate of the particle through the optical chamber as explained in the design document TIDA-00378.

    Let me check with the designer if he has more data.

    Vaibhavi Shanbhag

  • Hi  Vaibhavi,

    Thanks for your explanation. So we can take experiments to find the frequency range of different samples.

    And do you get more data?

    Boli Huang

  • Hi Boli,

    Yes, if the air flow is not known, then measurements can be made to determine the spectrum in an environment with known concentration and particle size.

    If you are planning to pulse the LED, (to save power or to maintain the safe operating area of LED in case of high LED current) then the filter will have to be modified such that the settling occurs before the end of the LED pulse so that a sufficient number of ADC samples can be taken. Depending on how short the LED pulses are, this may require a higher bandwidth design than what is shown in the TIDA -00378 design document.

    Vaibhavi Shanbhag