How to increase/control the time spent on each frequency for EIS measurement

Hi,

   The parameters controlling impedance measurement time are 

- WaitClks

- ImpODR

For variable measurement time, add variable time to "waitclks" inside AppIMPSeqMeasureGen() function:

 AD5940_SEQGenInsert(SEQ_WAIT(WaitClks + x ));

For longer measurement times, reduce ImpODR.

Hi Akila,

I tried implementing this.

My main problem is that the result of EIS on low frequencies from 1Hz to around 120Hz is pretty bad. The full range of measurement is from 1Hz to 10kHz which I am interested in. However, both magnitude and Phase measurement at lower frequencies is really bad.

I tried reducing the impODR to 0.00001 but there is no improvement in the readings. Could you please suggest what I should do to improve the readings? I am using a 2 wire sensor.

Thanks

Hi,

 Depending on the load, different filter settings may be required for this frequency range (1Hz to around 120Hz).

Filter settings are

DftSrc,
ADCSinc2Osr,
ADCSinc3Osr,
DftNum,
PwrMod,

HstiaRtiaSel,

ADCRate.

Reference : AD5940_GetFreqParameters() function defined in ad5940.c library file.

Hi ,

There is no callback to this function in ADUCM355 EIS examples. can you please check this?

Thanks

Hi ,

There is no callback to this function in ADUCM355 EIS examples. can you please check this?

Thanks

Hi, 

It is not called in EIS example.

This function can be used for tuning filter settings w.r.t. frequency.

You may use https://github.com/analogdevicesinc/ad5940-examples/tree/master/examples/AD5940_Impedance_Adjustable_with_frequency as reference 

for code modification.

Similar discussion : (+) Help Configuring AD5940 for Two-Wire EIS Measurement with CE0 and SE0 - Q&A - Precision ADCs - EngineerZone