ctsd16_ex1_singleChContConv.c

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//******************************************************************************
//  MSP430FG662x Demo - CTSD16, Continuous Rail-to-Rail Conversion, Single Channel
//
//  Description: This program uses the CTSD16 module to perform continuous
//  conversions on a single channel with rail-to-rail input. A CTSD16 interrupt
//  occurs when a conversion has completed.
//
//  Test by applying voltages to the input channel and setting a breakpoint
//  at the indicated line. Run program until it reaches the breakpoint, then use
//  the debugger's watch window to view the conversion results.
//
//  Results (upper 16 bits only) are stored in the array "results"
//
//  ACLK = 32kHz, MCLK = SMCLK = Calibrated DCO = 16.384MHz, SD_CLK = 1.024MHz
//
//  Notes: For minimum Vcc required for CTSD16 module - see datasheet
//         1nF cap btw Vref and AVss is recommended when using 1.2V ref
//
//               MSP430FG662x
//             -----------------
//         /|\|                |
//          | |                |
//          --|RST             |
//            |                |
//   Vin1+ -->|A0.0+      VREF |---+
//   Vin1- -->|A0.0-           |   |
//            |                |  -+- 1nF
//            |                |  -+-
//            |                |   |
//            |           AVss |---+
//
//******************************************************************************
 
#include "driverlib.h"
 
uint32_t results[8];
 
void main(void) {
    // Stop WDT
    WDT_A_hold(WDT_A_BASE);
 
    // Select AD0+/- analog input pins
    GPIO_setAsPeripheralModuleFunctionInputPin(GPIO_PORT_P6, GPIO_PIN4 | GPIO_PIN5);
 
    // Initialize CTSD16 using internal reference and internal resistor for clock
    CTSD16_init(CTSD16_BASE,
            CTSD16_RTR_INPUT_CHARGEPUMP_BURST_REQUEST_DISABLE, CTSD16_REF_INTERNAL);
 
    // Initialize converter 0: AD0+ / AD0- as input, 2s complement, channel 9
    CTSD16_initConverterAdvancedParam convAdvParam = {0};
    convAdvParam.converter = CTSD16_CONVERTER_0;
    convAdvParam.conversionMode = CTSD16_CONTINUOUS_MODE;
    convAdvParam.groupEnable = CTSD16_NOT_GROUPED;
    convAdvParam.inputChannel = CTSD16_INPUT_CH9;
    convAdvParam.dataFormat = CTSD16_DATA_FORMAT_2COMPLEMENT;
    convAdvParam.railToRailInput = CTSD16_RTR_INPUT_ENABLE;
    convAdvParam.interruptDelay = CTSD16_FOURTH_SAMPLE_INTERRUPT;
    convAdvParam.oversampleRatio = CTSD16_OVERSAMPLE_256;
    convAdvParam.gain = CTSD16_GAIN_1;
    CTSD16_initConverterAdvanced(CTSD16_BASE, &convAdvParam);
 
    // Clear converter 0 interrupt flags
    CTSD16_clearInterrupt(CTSD16_BASE, CTSD16_CONVERTER_0,
            CTSD16_CONVERTER_INTERRUPT|CTSD16_CONVERTER_OVERFLOW_INTERRUPT);
    // Enable converter 0 overflow, result interrupts
    CTSD16_enableInterrupt(CTSD16_BASE, CTSD16_CONVERTER_0,
            CTSD16_CONVERTER_INTERRUPT|CTSD16_CONVERTER_OVERFLOW_INTERRUPT);
 
    // Delay ~120us for 1.2V ref to settle
    __delay_cycles(2000);
 
    // Wait for rail-to-rail input ready
    while(!CTSD16_isRailToRailInputReady(CTSD16_BASE));
 
    // Set bit to start conversion
    CTSD16_startConverterConversion(CTSD16_BASE, CTSD16_CONVERTER_0);
 
    __bis_SR_register(LPM0_bits | GIE);     // Enter LPM0 w/ interrupts
}
 
#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector=CTSD16_VECTOR
__interrupt
#elif defined(__GNUC__)
__attribute__((interrupt(CTSD16_VECTOR)))
#endif
void CTSD16_ISR(void) {
    static uint8_t index = 0;
    switch (__even_in_range(CTSD16IV,CTSD16IV_CTSD16MEM0)) {
        case CTSD16IV_NONE: break;
        case CTSD16IV_CTSD16OVIFG:
            // Clear overflow interrupt explicitly
            CTSD16_clearInterrupt(CTSD16_BASE, CTSD16_CONVERTER_0, CTSD16_CONVERTER_OVERFLOW_INTERRUPT);
            break;
        case CTSD16IV_CTSD16MEM0:
            // Save CH0 results (clears IFG)
            results[index++] = CTSD16_getResults(CTSD16_BASE, CTSD16_CONVERTER_0);
            if(index >= 8) {
               index = 0;                 // SET BREAKPOINT HERE
            }
            break;
        default: break;
    }
}