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.

MSP430F5359: ADC gets stuck on raw 2048

Part Number: MSP430F5359

I am using MSP430F5359, my raw ADC value get stuck at 2048.  For example, if my voltage is such that the raw values are 1900, I can keep increasing the voltage till it is about 1990, then the raw values jump to 2048 and then stay at 2048 till the voltage is high enough for 2050, then the become linear and normal again.  Any ideas why?

the ADC12A is configured using the following code:

    REFCTL0 &= ~REFMSTR;  // Reset REFMSTR to hand over control to
                          // ADC12_A ref control registers

    ADC12CTL0 = ADC12SHT1_5 +  // Sample Hold
                ADC12SHT0_5 +  // Sample Hold
                ADC12REF2_5V;  // Enable 2.5Volt Reference

    ADC12CTL1 = ADC12SHP +         // use sampling timer
                ADC12CONSEQ_0 +    // Use sampling timer, single sequence
                ADC12CSTARTADD_9;  // Start scan with channel 9

    ADC12CTL2 = ADC12RES_2 +    // 12 bit resolution
                ADC12SR +       // slower, lower power sampling rate
                ADC12REFBURST;  // Reference is only on when converting

    ADC12MCTL9 = ADC12INCH_4 + ADC12SREF_1;  // Press 1,Vr+=Vref+ and Vr-=AVss

To begin sampling the system executes the following code:

    ADC12CTL0 |= ADC12ON +     // Turn on ADC
                 ADC12REFON +  // Turn on the voltage reference
                 ADC12ENC;     // Enable Conversion

    ADC12IE |= ADC12IE9;  // Enable interrupt

Then each conversion is started by:

ADC12CTL0 |= ADC12SC;  // Enable Conversion