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Starterware/MSP430FR6972: how to calculate ADC12_B sample frequency exactly

Jent
Intellectual 660 points

Part Number: MSP430FR6972

Tool/software: Starterware

Hi Sir，

I want to know how to calculate ADC12_B sample frequency exactly. From the page 673 of MSP430FR6972 User's Guide , I knew that the ADC sample period  is composed by  sample time， sync time ，convert time and one clock cycle. The picture is following :

But ,I have some doubts:

1. how long does the sync time?

2.what's the means of ADC local reference buffer ?  Is the reference voltage generated by REF_A module a ADC local reference buffer?

3.what clock is the one clock cycle 's  clock source， MCLK or ADC12_B clock?

Regrads,

Jent

  • 0
    TI__Guru**** 223927 points
    Hi Jent,

    1. Sync time is less than one clock cycle as it waits for the next rising edge of ADC12CLK, it can generally be thought as 0.5 ADC12CLK cycles on average.
    2. If ADC12VRSEL= 0001, 0011, 0101, 0111, 1001,1011, 1101, or 1111 then the REF_A buffer is used and the ADC must wait for ADC12RDYIFG to set.
    3. ADC12_B clock.

    The best way to evaluate your exact sample frequency is by generating test code and measuring the time between completed conversions. This will also depend on the conversion initiation and mode selected.

    Regards,
    Ryan

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