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Topic: Try this super fast analog pin logger (Read 81864 times) previous topic - next topic

Ross2511

Hello,

Thanks for the awesome code, i'm successfully recording at 8 kHz using the uno and the adafruit data shield.

My measurement system is going to used to detect coughs and ideally id like to call the time stamp about once every minute or five minutes just to confirm the sampling frequency.

Is it possible to write the time stamp in binary? Would it be easier to utilise the seconds from midnight 01/01/1970 function that the adafruit data logger has?

Thanks

Ross

Ross2511

#106
Nov 27, 2018, 09:57 am Last Edit: Nov 27, 2018, 10:20 am by Ross2511
Following on from my previous post i have been running experiments to evaluate if the sampling intervals are stable enough to allow me to only use the sample number as the time. My project involves an electret microphone recording audio for cough detection.

Using a digital clock with milliseconds i would sound a buzzer directly above the microphone (for 1s) to register a 5V signal. I then used MATLAB to identify the time of these peaks using the sampling interval along with the sample number and check them against the time i've recorded applying the beep.

Although no overruns are reported when the recording ends the times of the beeps identified on MATLABb seem to almost drop by 4s an hour. I am running these tests for between 3-4 hours but eventually would like to run this project for 24 hours.

I initially was recording at 10kHz with the clock running at 250kHz. I then tried to increase clock speed to 500kHz but that seemed to increase the error.

Finally i decreased to 5kHz sampling frequency to 5kHz with a clock speed of 125kHz.

Has anyone else had experience with this?

Thanks in advance for any suggestions, i have attached screenshots of the result tables.

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