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MSP430FR2355: Reading Internal Temperature of MSP430FR2355 Device

Zegeye Alemu1
Prodigy 155 points
Part Number: MSP430FR2355
Other Parts Discussed in Thread: MSP430WARE

Hello,

I am currently accessing the internal temperature sensor of the MSP430FR2355 device.

Just to be in the same page:

My ADC initialization is similar to all ADC Channels except the followings:

   * I enable the temperature sensor

         PMMCTL0 = PMMPW;
         PMMCTL2 |= TSENSOREN | INTREFEN; 

   * I configure ADC to use the internal Default reference voltage, 1.5V

          ADCMCTL0 &= ~ADCSREF;
          ADCMCTL0 |= ADCSREF_1;

   * I perform a read from Channel 12

   * I transform the read ADC value to Temperature

     I use the formula given in section 1.13.3.3 of the user's manual (slau445i.pdf).

     I use Formula 10.

     The ADC-105C and ADC-30C calibration values for the formula above is retrieved from Word Addresses 0x1A1C and 0x1A1A respectively.

     For some reason, the temperature I am reading is OFF by 20C or so. Room temp is about 25C and what I am reading is around 45C.

     Can you please check if I have neglected to include in consideration above?

     Would you please supply me with a working sample code?

 Thanks in advance for your help and support.

 Best regards,

 Ziggy

  • 0
    TI__Mastermind 32920 points

    I think you can find the example code from MSP430ware. Have you give enough sampling time for the temp sensor?

  • 0 in reply to Eason Zhou
    Prodigy 155 points

    Good Morning Eason,

    Thank YOU very much for your response.

    Interestingly, when I looked for the sample code, did not see it at the time.

    Checked it again and I found a sample code.

    That said, like you suspected, 16 clock cycles for sample and hold time was not good enough.

    Example code was using 256 clock cycles. Once I changed that, I started reading the correct temperature.

    Thanks again for your help and support.

    Best regards,

    Ziggy

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