MSP430FR5043: "Start PPG Count(ns)" and "Turn on ADC Count(ns)"

Part Number: MSP430FR5043

Tool/software:

Hi team,

(same opportunity from the quoted E2E thread)

Customer is not sure what should be considered when decide "Start PPG Count(ns)" and "Turn on ADC Count(ns)"

Do you have any documents explaining these?

Customer doesn't understand what it does mean and doesn't understand why these setting are needed.

Regards,

Hayashi

  • Hi Diego,

    That's helpful. Regading the post, customer have additional question in detail.

    [(1) the device family User's guide slau367 section 21.8.37 shows below

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    TIMEMARK A event is to trigger the PPG. Before this event, the Tx bias is applied to the transmit channel, so make sure to provide enough time to settle the Tx bias. The minimum value is two.

    -------

    Q1. How much range does "enough time" mean?

    Q2. "The minimum value is two" in this paragraph. Does it mean "2 bit" or "2 ns (nano second)" or others?

    (2) the device family User's guide slau367 section 21.8.38 shows below

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    TIMEMARK B event is to turn on the SDHS (ADC converter). The SDHS starts sampling input signal at the TIMEMARK D event. The time between B and D is for the SDHS settling time. The minimum value is two.

    -------

    Q3.  "The minimum value is two" in this paragraph. Does it mean "2 bit" or "2 ns (nano second)" or others?

    Q4. Are there no restriction such as "enough time" in section 21.8.37?

    (3) The E2E thread you guided mention below

    -------

    So basically, the formula is  [Gap between pulse start and ADC capture] + [Start PPG count (ns)] - [Turn on ADC count (ns)] > [SDHS settling time (40 us)]

    -------

    Customer wants to know reasonable range. For example, it is able to set as extreme relationship as 

    [Gap between pulse start and ADC capture] : 41(us)

    [Start PPG count (ns)] : 2(ns?)

    [Turn on ADC count (ns)] : 2(ns?)

    Q5. Anything to be considered to set the values?

    To consider the example, ADC turns on by 2ns, and ADC waits for 41us with useless current consumption, and then start capturing.

    Best regards,

    Hayashi

  • Hi Hayashi,
    Q1. This is most likely referring to the value in the register, AKA it needs to at least wait for the minimum value in TIMEMARK_A. 
    Q2 & Q3. This refers to a value of 2 inside the register
    Q4. No restrictions are mentioned in the register description. Just keep in mind the SDHS times you see in the description. 
    Q5. For this part, I would recommend reading the TIDM-02003 Design guide.
    If you have more questions adjacent to this, I recommend creating a separate E2E for them.
    Best Regards,
    Diego Abad

  • H Diego,

    Q5. For this part, I would recommend reading the TIDM-02003 Design guide.

    Sorry I can't find a right part to explain. Could you specify where it is?

    Regards,

    Hayashi

  • Hi Hideki,
    I recommended reading page 25, section 3.2.1.5 Customization and Optimization, for some reference and the variables you were looking for. However, as long as you follow what the previous E2E recommended, it should be ok according to the Userguide.
    Best Regards,
    Diego Abad

  • Hi Diego,

    Understood about the documents. I'll add more detail about the customer's issue here.

    1. When they set "Start PPG Count" under 33,000, there are no output value of flow rate.

    2. At specific relashionship in "Start PPG Count" and "GUI Based Gain Control", there are some mysterious thing. When gain is only 26, 36, or 56, it shows flow rate, but other than them, no output. In addition, when gain is 26, flow rate is output once, but there will no change after changing the reference flow rate (measured gas).

    Do you have some idea to resolve this problem?

    Regards,

    Hayashi

  • Hi Hideki,
    I recommend to post this questions as another E2E thread. 

    Best Regards,

    Diego Abad

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