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data rates ADXL345

Question asked by gandhi on Nov 26, 2015
Latest reply on Dec 1, 2015 by gandhi

Hello

Presently I'm working for a data logging project with ADXL345 sensor. I'm looking to get highest data rates and want to store in a flash memory.

When i try to store the output in spansion serial memory like S25FL128S......

Unfortunately The output data rates for 3200HZ is 1900

                                                     for  1600HZ is 1820HZ  (with 1555 variations in the output)

                                                     for 800HZ   is  843 with 820 variations.

And when i try to store in FRAM (8KB)

     the output data rates are unknown due to shortage of memory but for 3200HZ all samples are different to each other.

                                      but for 1600HZ every sample repeated twice.

                                           for 800HZ  the output samples are 1020 ( could be more...memory full) with 730 variations.

                                             from 400HZ to 3.13 HZ input the output data rates are 672 samples with respective variations.

 

I'm attached excel sheet with all sampling rates also mentioned I/P freq and all other data.

my question is for both memories the input freq from the sensor is same for respective data rates.. according to the data sheet.

But the output data rates are different for each memory.

Is it normal to get such huge data rates and repeated data rates?.

Do we get exact data rates as mentioned in the data sheet?

Is data rates are depend on spi frquency for memory?.

Can i get exactly 50HZ output samples for input 50HZ data rates unlike my situation where i got 672 samples with 50 variations?.

 

Thank you.

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