adc12_b_ex3_extRef.c

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//******************************************************************************
//  MSP430FR59xx Demo - ADC12B, Using an External Reference
//
//  Description: This example shows how to use an external positive reference for
//  the ADC12B. The external reference is applied to the VeREF+ pin. AVss is used
//  for the negative reference. A single conversion is performed on channel A0.
//  The conversion results are stored in ADC12BMEM0 and Test by applying a voltage
//  to channel A0, then setting and running to a break point at the "_NOP()"
//  instruction. To view the conversion results, open an SFR window in debugger
//  and view the contents of ADC12BMEM0.
//  NOTE: VeREF+ range: 1.4V (min) to AVCC (max)
//        VeREF- range: 0V (min) to 1.2V (max)
//        Differential ref voltage range: 1.4V(min) to AVCC(max)
//          (see datasheet for device specific information)
//
//
//                MSP430FR5969
//             -------------------
//         /|\|                   |
//          | |                   |
//          --|RST                |
//            |                   |
//     Vin -->|P1.0/A0            |
//            |                   |
//     REF -->|P1.1/VREF+/VeREF+  |
//            |                   |
//
//******************************************************************************
#include "driverlib.h"
 
void main(void)
{
    // Stop WDT
    WDT_A_hold(WDT_A_BASE);
 
    //Set P1.0 as Ternary Module Function Output.
    /*
 
    * Select Port 1
    * Set Pin 0 to output Ternary Module Function, (A0, C0, VREF-, VeREF-).
    */
    GPIO_setAsPeripheralModuleFunctionInputPin(
        GPIO_PORT_P1,
        GPIO_PIN0,
        GPIO_TERNARY_MODULE_FUNCTION
    );
 
    /*
     * Disable the GPIO power-on default high-impedance mode to activate
     * previously configured port settings
     */
    PMM_unlockLPM5();
 
    //Initialize the ADC12B Module
    /*
    * Base address of ADC12B Module
    * Use internal ADC12B bit as sample/hold signal to start conversion
    * USE MODOSC 5MHZ Digital Oscillator as clock source
    * Use default clock divider/pre-divider of 1
    * Not use internal channel
    */
    ADC12_B_initParam initParam = {0};
    initParam.sampleHoldSignalSourceSelect = ADC12_B_SAMPLEHOLDSOURCE_SC;
    initParam.clockSourceSelect = ADC12_B_CLOCKSOURCE_ADC12OSC;
    initParam.clockSourceDivider = ADC12_B_CLOCKDIVIDER_1;
    initParam.clockSourcePredivider = ADC12_B_CLOCKPREDIVIDER__1;
    initParam.internalChannelMap = ADC12_B_NOINTCH;
    ADC12_B_init(ADC12_B_BASE, &initParam);
 
    //Enable the ADC12B module
    ADC12_B_enable(ADC12_B_BASE);
 
    /*
    * Base address of ADC12B Module
    * For memory buffers 0-7 sample/hold for 16 clock cycles
    * For memory buffers 8-15 sample/hold for 4 clock cycles (default)
    * Disable Multiple Sampling
    */
    ADC12_B_setupSamplingTimer(ADC12_B_BASE,
      ADC12_B_CYCLEHOLD_16_CYCLES,
      ADC12_B_CYCLEHOLD_4_CYCLES,
      ADC12_B_MULTIPLESAMPLESDISABLE);
 
    //Configure Memory Buffer
    /*
    * Base address of the ADC12B Module
    * Configure memory buffer 0
    * Map input A0 to memory buffer 0
    * Vref+ = AVcc
    * Vref- = EXT Positive
    * Memory buffer 0 is not the end of a sequence
    */
    ADC12_B_configureMemoryParam configureMemoryParam = {0};
    configureMemoryParam.memoryBufferControlIndex = ADC12_B_MEMORY_0;
    configureMemoryParam.inputSourceSelect = ADC12_B_INPUT_A0;
    configureMemoryParam.refVoltageSourceSelect = ADC12_B_VREFPOS_EXTPOS_VREFNEG_VSS;
    configureMemoryParam.endOfSequence = ADC12_B_NOTENDOFSEQUENCE;
    configureMemoryParam.windowComparatorSelect = ADC12_B_WINDOW_COMPARATOR_DISABLE;
    configureMemoryParam.differentialModeSelect = ADC12_B_DIFFERENTIAL_MODE_DISABLE;
    ADC12_B_configureMemory(ADC12_B_BASE, &configureMemoryParam);
 
    while (1)
    {
        //Enable/Start first sampling and conversion cycle
        /*
         * Base address of ADC12B Module
         * Start the conversion into memory buffer 0
         * Use the single-channel, single-conversion mode
         */
        ADC12_B_startConversion(ADC12_B_BASE,
            ADC12_B_MEMORY_0,
            ADC12_B_SINGLECHANNEL);
 
        //Poll for interrupt on memory buffer 0
        while (!ADC12_B_getInterruptStatus(ADC12_B_BASE,
                   0,
                   ADC12_B_IFG0));
 
        __no_operation();                       // SET BREAKPOINT HERE
        }
}