MSP430F5529: Reading from ADC12 with driverlib - Always small value and sometimes never receives interrupt

Part Number:MSP430F5529

Hi

I am new to the MSP430 family, and any help will be appreciated.

I am trying to read from the onboard ADC. However I have 2 problems:

1. For some channel values (in the switch statement), no interrupt is called, so the processor gets stuck in the while loop waiting for the interrupt. (I know I need to add code to timeout of the loop)

2. For channel values where the interrupt is called, when I get the results it is always a small value <15.

Here is some code (heavily based on the example code in the DriverLib Users Guide:

In the main init function called at the top of main()

    // Initialize ADC12 with ADC12’s built-in oscillator
    ADC12_A_init(ADC12_A_BASE,
                 ADC12_A_SAMPLEHOLDSOURCE_SC,
                 ADC12_A_CLOCKSOURCE_ADC12OSC,
                 //ADC12_A_CLOCKDIVIDEBY_1);
                 ADC12_A_CLOCKDIVIDER_1);

My Function for reading from the ADC

uint16_t read_analog(int channel) {
    //Switch ON ADC12
    ADC12_A_enable(ADC12_A_BASE);

    // Setup sampling timer to sample-and-hold for 16 clock cycles
    ADC12_A_setupSamplingTimer(ADC12_A_BASE,
                               ADC12_A_CYCLEHOLD_64_CYCLES,
                               ADC12_A_CYCLEHOLD_4_CYCLES,                        
                               0);

    // Configure the Input to the Memory Buffer with the specified Reference Voltages
    ADC12_A_configureMemoryParam param = {0};
    param.memoryBufferControlIndex = ADC12_A_MEMORY_0 + channel;
    param.inputSourceSelect = ADC12_A_INPUT_A0 + channel;
    param.positiveRefVoltageSourceSelect = ADC12_A_VREFPOS_AVCC;
    param.negativeRefVoltageSourceSelect = ADC12_A_VREFNEG_AVSS;
    param.endOfSequence = ADC12_A_NOTENDOFSEQUENCE;
    ADC12_A_configureMemory(ADC12_A_BASE, &param);

    // Start a single conversion, no repeating or sequences.
    ADC12_A_startConversion(ADC12_A_BASE,
                            ADC12_A_MEMORY_0 + channel,
                            ADC12_A_SINGLECHANNEL);

    // Wait for the Interrupt Flag to assert
    // Get appropriate interrupt id, also if the argument is a channel we do not use, return -1
            switch (channel) {
            case 5 :
                while( !(ADC12_A_getInterruptStatus(ADC12_A_BASE,ADC12IFG5)) );
                break;
            case 6 :
                while( !(ADC12_A_getInterruptStatus(ADC12_A_BASE,ADC12IFG6)) );
                break;
            case 7 :
                while( !(ADC12_A_getInterruptStatus(ADC12_A_BASE,ADC12IFG7)) );
                break;
            case 12 :
                while( !(ADC12_A_getInterruptStatus(ADC12_A_BASE,ADC12IFG12)) );
                break;
            case 13 :
                while( !(ADC12_A_getInterruptStatus(ADC12_A_BASE,ADC12IFG13)) );
                break;
            default:
                return(-1);
            }

    // Get the value
    uint16_t data = ADC12_A_getResults(ADC12_A_BASE, ADC12_A_MEMORY_0 + channel);

    // Disable the ADC
    ADC12_A_disable(ADC12_A_BASE);

    return(data);
}