This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

MSP430F5328 Built in temperature sensor question

Other Parts Discussed in Thread: MSP430F5328

I am using an msp430f5328 and want to utilize ADC with the built-in temperature sensor for my application.  However, it seems I have found a discrepancy, and I am hoping someone can help clear up my confusion.

It says in the MSP430x5xx and MSP430x6xx Users Guide that the built-in temperature sensor must have a sampling period of 30us, but then in the Data Sheet is says that the sample time required is at a minimum of 100us.  My assumption is to follow the data sheet is specific to this particular board.  Am I right in my assumption?

Secondly, does this 100us mean I have to set my sample-hold time to 512 cycles (Using the internal 5MHz sampling clock on the board, resulting in 102.4us), or can I simply turn the board on, wait for 100us, and then start sampling the sensor at a lower sample-hold time? 

  • Christopher Carl said:
    must have a sampling period of 30us

    No, it says greater than 30uS, this is in general and then comes the specific data sheet and there you are right.

    Christopher Carl said:
    I have to set my sample-hold time to 512 cycles

    Correct.

    Christopher Carl said:
    or can I simply turn the board on, wait for 100us, and then start sampling the sensor at a lower sample-hold time? 

    When at power-up the ADC is initialized and the desired channel is selected, yes.

    But at power-up the ADC is not initialized and the desired channel is not selected, so the answer is no.

    Read carefully, and tries to understand chapter ‘28.2.5.3 Sample Timing Considerations’. The voltage over Ci will be used for the conversion and T=R*C.

  • That answered my question.  Thanks so much!

**Attention** This is a public forum