I change BiaODR value, but the sampling frequency w does not change as this.So I would like to ask how to change the sampling frequency in the 4-wire BIA measurement, because I need a sampling frequency of 1000hz.thanks.
AD5940
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The AD5940 and AD5941 are high precision, low power analog front ends (AFEs) designed for portable applications that require high precision, electrochemical...
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AD5940 on Analog.com
I change BiaODR value, but the sampling frequency w does not change as this.So I would like to ask how to change the sampling frequency in the 4-wire BIA measurement, because I need a sampling frequency of 1000hz.thanks.
Hi,
With the default AFE configuration, max allowed ODR is 10Hz.
For ODR more than this, ADC filter parameters must be changed.
If you are running the code through IDE (Keil or IAR), you may add the below code ) inside AppBIASeqMeasureGen () and add to watch “AppBIACfg.MaxODR”, to know the maximum sampling rate allowed for the set configuration.
AppBIACfg.MeasSeqCycleCount = AD5940_SEQCycleTime();
AppBIACfg.MaxODR = 1/((( AppBIACfg.MeasSeqCycleCount + 10) / 16.0)* 1E-6) ; //If Sysclk is16MHz
if(AppBIACfg.BiaODR > AppBiaCfg.MaxODR)
{
/* We have requested a sampling rate that cannot be achieved with the time it takes to acquire a sample.*/
AppBIACfg.BiaODR = AppBIACfg.MaxODR;
}
With the default AFE configuration, max allowed ODR is 10Hz.
thanks,Actually it already exists.But the sampling frequency does not change.so I want to know what BiaODR is for.
Hello,
Has this issue been resolved? I have a similar problem as well. Thank you!.
No, this question still haunts me.and What is your question?
Hi,
Changing the below parameters in BodyImpedance.c file changes maxODR:
AppBIACfg.DftNum
AppBIACfg.ADCSinc2Osr
AppBIACfg.ADCSinc3Osr
Hello Akila,
Thank you for the prompt response! I was wondering what exactly should be changed within those lines of code. I was looking at the BIOZ-2Wire example and I don't see any numerical values for me to change given the codes you just provided.
This is what I am currently seeing:
OR
Thank you!
Very similar to your question about the sampling rate for the AD5940 Board
Hi,
Because I calculated the value of maxodr is 47 , So no matter how I change the Biaodr value, there is no effect on the output frequency.
so can I delete the configuration of maxodr in here? only use the Biaodr。
Hi,
If MaxODR is 47 samples/s and if you are setting BiaODR =50, it is not going to provide 50Hz Output rate. Hence keeping the MaxODR block ensures clarity.
Hi,
Then how can I increase the output frequency to more than 50hz?
Do I have to raise the MAXODR, and how do I increase the value of this?
Change
pBIACfg->DftNum = DFTNUM_8192;
pBIACfg->ADCSinc3Osr = ADCSINC3OSR_2;
in AD5940Main.c
and
.ADCSinc2Osr = ADCSINC2OSR_22,
in BodyImpedance.c
But when I change these values,the accuracy of the data decreases
But when I change these values,the accuracy of the data decreases
It would be good to know the FULL code modfications to get to 1000Hz sampling rate, which would be similar to a benchtop Zurich instrument, which we would like to compare to. There seems to be lots of partial code answers - please provide the full code and maximum sampling rate and ideally the loss in accuracy from the 4Hz example in the documentation and the desirable 1000Hz sampling rate.