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S32K144 ADC Slow Sample Rate in FreeMaster

Question asked by sparkee on May 13, 2020
Latest reply on May 20, 2020 by Marius-lucian Andrei

I never got an answer as to why FreeMaster won't show a sample rate faster than ~1ms.  I've tried both PDB and ISR reads and get a similar sample rate.  I've recorded the data to file and it's no different. 

 

I'm only reading a single ADC channel (I've also tried with 2 and no difference).  I've tried with and without hardware averaging.  FreeMaster won't connect when hardware averaging is set to 32 samples, but the rest show no difference that I can see. 

 

The only thing that made a noticeable difference to me was changing the sample time down to 2 from around 15.  That definitely made a small difference. 

 

I know FreeMaster is capable of faster reading and I know the hardware is capable so it must be something I'm doing wrong in the setup.  Any help will be greatly appreciated.

 

I'm using S32K144EVB and FreeMaster 3.0.  I have fixed step size set to 0.00001 (also tried at 0.0001).

I'm feeding the ADC a 60Hz sine wave that has been rectified and is a few hundred millivolts peak.

 

 

PDB triggers every 0.1ms

No hardware averaging

 

Hardware averaging 8 samples

 

 

 

Changed ADC sample time from 15 down to 2 and saw a change.

 

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