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MSP430FR2155: About Pulse Sample Mode With Internal Reference in 12-Bit Mode

Cruijff
Expert 2760 points

Part Number: MSP430FR2155

Hi community member,

My customers have the following doubts.
""In Figure 21-8, it seems that Down of SHI signal and Down of SAMPCON are synchronized.
In Pulse Sample ModeWith Internal Referee, with regard to StopSampling, it is correct by the recognition that it is synchronized with the Down of the SHI signal?""

I think that SHI is only used to trigger the start of sampling, and I do not think it is necessary to have SHI DOWN wait until Tsample.
Figure 21-8 is exactly like figure 21-5, but is it the correct figure?

Best regards.
Cruijff

  • 0
    TI__Genius 17960 points
    Hello Cruijff,
    sorry, but from your description is not clear, which documents you're referring to. Please be more accurate in your problem description. Many thanks in advance.

    Best regards
    Peter
  • 0 in reply to Peter Spevak
    Expert 2760 points

    Hi Peter

    Thank you for your reply.
    "Figure 21-8." points to the user's guide page of 545. (SLAU445h)

    I think the sampling time of SHI in this figure is very long.

    Best regards.
    Cruijff

  • 0 in reply to Cruijff
    TI__Genius 17960 points

    Hi Cruijff,

    many thanks for the clarification.

    I need to double check the correctness of Figures 21-8 and 21-5 with our designers.

    What is the background of the question? Why is the customer concerned about the SHI signal? According to the description of the Pulse Sample mode, the Sample Timer is controlling the sampling time.

    What I have realized, the block diagram of  the User's Guide is missing the information about the SHI signal. For clarification please see the Figure below.

    Best regards

    Peter

  • 0 in reply to Peter Spevak
    Expert 2760 points

    Hi Peter,

    Thank you for posting the SHI signal in the figure.

    As my customers were trying to develop with ADC, but they are asking questions because they can not understand the contents of Figure 21-8.

    In Figure 21-8, the SHI signal was High while waiting for Tsample.
    I thought that this contradicted the explanation of Pulse Sample Mode.

    Pulse Sample Mode interpreted that Tsample is determined by ADCSHP = 1 and ADCSHTx, Specify only Start Sampling for the SHI signal.
    Is this interpretation wrong?

    Best regards.
    Cruijff

  • 0 in reply to Cruijff
    TI__Genius 17960 points
    Hi Cruijff,
    no the interpretation of yours/customer, that in the Pulse sample mode the SHI is only responsible for the start of the sampling and the sampling time is defined by the sampling timer is correct.
    Thus Figure 21-8 is definitely confusing.
    I am checking about the clarification of this figure.

    Best regards
    Peter
  • 0 in reply to Peter Spevak
    Expert 2760 points

    Hi Peter,

    Thank you for your reply.

    I was relieved that the interpretation of me and my customers was correct.
    Please tell me if Figure 21-8 seems to change.

    Best regards.
    Cruijff

  • 0 in reply to Cruijff
    TI__Genius 17960 points

    Hi Cruijff,

    I can confirm, the figures for the pulse sample mode in the User's Guide need to be corrected. For reference you could use the Figures in the FR5xx/FR6xx User's Guide.

    Best regards,

    Peter

  • 0 in reply to Peter Spevak
    Expert 2760 points

    Hi Peter,

    FR5x User 's Guide was also helpful.
    I hope that FR2x will also be fixed.

    I appreciate your help.

    Thank you!
    Cruijff

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