I am very new to using accelerometers and am not sure what the evaluation board for the ADcmXL 1021-1 is actually giving me as its outputs. I have tried reading the datasheets and searching online for more information, but I think some of the wording is beyond my current comprehension. I am able to get data from the eval board through my laptop and it gives me graphs and data on a csv file, but I don’t know what the data really is. I have used both MTC and MFFT and I know the MTC graphs has (g) on the y-axis, but the MFFT graph does not have any units for the y-axis, only Hz on the x-axis. And then the csv file data also as no units so I am confused as to what the data actually is. Any help would be appreciated, even if it is just directing me somewhere else. Again, I am extremely new to this stuff as this is my first time using accelerometers so I applogise for my lack of knowledge in this area. Thank you!

From the information that I am seeing for this part, ADCMXL 1021-1, it is a single axis accelerometer. This would be why there is only information for the x-axis. The main purpose for this sensor is vibration and explains why you are only seeing Hz on the x-axis.

Hi, thank you for your response, but I was referring to the axes of the graph given in the evaluation kit software. I’m attaching a picture of a graph given in the data sheet (which I probably should have done to begin with, so I apologise), and the one I have measures in the z-axis, but the horizontal axis of this graph has Hz and the vertical axis has no units which is what is confusing me.

Hi titusk,

As found on page 12 of the user’s manual for the EVAL-ADCM-1 kit, “MTC” refers to “Manual Time Capture” mode and “MFFT” refers to “Manual Fast Fourier Transform” mode.

MTC will give you an output of “g” magnitude over a period of time.

An FFT is a means of taking a number of samples and calculating at which frequencies a signal is present. It also will calculate the relative magnitudes at each frequency. So, the MFFT graph will show the frequencies where it is detecting a signal and show magnitude at those frequencies. The output of the sensor is digital, with a range of 0 ~ 65535 (16 bits of resolution), so the Y-axis of the graph is showing magnitude of acceleration at the frequencies on the X-axis.