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Samples and registers

Xingjun Goh
Prodigy 110 points
Other Parts Discussed in Thread: LM3S8962

Hi community,

I have a question regarding samples and registers. I am using Eks -lm3s8962 evaluation kit. It is a micro controller. This analog and digital, sample sequence inside the data sheet says it has only 17 registers. Ss4-1, ss3-4, ss2-4 and ss0-8. 8 +4+4+1 = 17.  Does it means this micro controller can only take a maximum of 17 samples from an input. And since it only reads the highest sample count. Which I initialize adc0 as my input. It means my sample length count N = 8.

Micro controller and digital signal processor are different right. A DSP can take in thousands of samples and some even more. They are faster and efficient than a micro-controller?

If any kind soul can help me out with these burning thoughts that I have?

  • 0
    TI__Guru**** 244400 points
    Hello Xingjun,

    The sample sequencer only contain the sequence of channels. Based on the number of channels being sampled. a trigger can be applied such that the trigger rate is slower than the rate of conversion for all channels. As an example if the Sampling rate for 1 channel is 1MSPS, then for 17 channels the overall rate is 1/17 MSPS, then a trigger at a rate slower than 1/17MSPS can be used to reacquire the samples.

    Regards
    Amit
  • 0 in reply to Amit Ashara
    Prodigy 110 points

    Hi,

    My apologies for my poor technical understanding. I haven actually got my answer or understand what you wrote. Probably I rephrased myself, for whatever that you have mentioned in the reply, does it means that. I can sample 10 million samples? The trigger rate or not trigger rate, slower or faster I do not quite understand what is it suppose to mean. Perhaps if you can explain to me how does that going to affect anything?  More specifically what I want to know is that, can the LM3S8962 microcontroller sample 100 million or 10 million samples or zillion and millions of samples? Does it have the capability to do so? Is it a yes or no? 

    You probably know what there is a datasheet for this LM3S8962. Because I am going for a lawsuit for this issue. Some professor told me that she can sample like a 100 million of samples, alot of samples. But as for what I understood from the datasheet, this microcontroller's datasheet states that the sample sequencer adds up to only 17 in total. Which means, it probably can only take in 17 samples at most? Maybe you can take this question and reply to me if the mentioned product LM3S8962  can afford to sample more than 17 samples? If whatever I have mentioned has got nothing to do with how many samples can it take in at one go, please highlight to me as well. I am a  non-technical guy trying to understand a technical reply from a technical expert like yourself Amit. 

    I apologise for any inconvenience that I have probably cause. 

  • 0 in reply to Xingjun Goh
    Guru 27665 points

    Xingjun Goh said:
    Because I am going for a lawsuit for this issue

    This strikes me as being a reason for getting an actual technical expert who can sit down with you and go over your technical concerns in detail.

    Robert

  • 0 in reply to Xingjun Goh
    TI__Guru**** 244400 points
    Hello Xingjun

    "But as for what I understood from the datasheet, this microcontroller's datasheet states that the sample sequencer adds up to only 17 in total."

    I want to understand which part of the data sheet tells that it will only do 17 total conversions.

    Regards
    Amit
  • 0 in reply to Robert Adsett
    Guru 47900 points
    One suspects that "not" all of the professor's students "Aced" her course...
  • 0 in reply to Amit Ashara
    Prodigy 110 points

    Hi in the DataSheet of LM3S8962 microcontroller, chapter 11 Analog to Digital Conversion page 397, mentioned about sample sequencer. 

    SSO has a FIFO, 8 registers deep and can therefore store 8 samples at a time. 

    Under Section 11.3.1 Sample Sequencer

    Sample Sequencer          Samples                  Depth of FIFO

    SS3                                     1                                      1

    SS2                                     4                                       4

    SS1                                     4                                      4

    SS0                                     8                                       8

    Adding 1 + 4 + 4 + 8 = 17? Total 

    As I initialised SSO to be used. SSO has a depth of FIFO (8). So meaning said that, it is 8 registers deep and can therefore store 8 samples at a time. 

    If I configure all the SS3, SS2, SS1 and SS0 to be used. Summing them 1 + 4 + 4 + 8 = 17. I have a total of 17 registers deep and can therefore store 17 samples at a time. So, at every cycle I can only take in 17 samples. This is being stated in the datasheet.

  • 0 in reply to Xingjun Goh
    TI__Guru**** 244400 points
    Hello Xingjun,

    Yes, every cycle would lead to 17 samples. However if the application reads the data and then triggers it again, then it is 2*17 samples. So for every N trigger the sample count goes N*17

    Regards
    Amit
  • 0 in reply to Amit Ashara
    Guru 47900 points

    In the attempt to add clarity - there IS a difference between the, "Number of Samples" made in, "One sample collection Sequence" (via this vendor's SS0-SS3 methods) and the, "Total Number of Samples Taken!"    Number of (total) samples taken - outside of time limitations - may reach (easily) into the millions.

    Yet another possibility is the, "Rate of Samples Taken" which may usually be represented as xSPS. (where x represents M(mega) or K(kilo) Samples/Second).
     
    Devil is in these details - even after multiple "back-forth" - which of the three methods described herein remains unknown...