vector_ex1_max_q15.c

This example demonstrates how to use the msp_max_q15 API to find the maximum value and index of a real vector.

//******************************************************************************
// Find the maximum value and index of a real vector.
//
// Brent Peterson, Jeremy Friesenhahn
// Texas Instruments Inc.
// April 2016
//******************************************************************************
#include "msp430.h"

#include <math.h>
#include <stdint.h>
#include <stdbool.h>

#include "DSPLib.h"

/* Input signal parameters */
#define FS                  8192
#define SAMPLES             200
#define SIGNAL_FREQUENCY    200
#define SIGNAL_AMPLITUDE    0.6

/* Constants */
#define PI                  3.1415926536

/* Input vector */
DSPLIB_DATA(input,4)
_q15 input[SAMPLES];

/* Result maximum value */
_q15 q15MaxVector;

/* Index of result */
uint16_t uint16MaxIndex;

/* Benchmark cycle counts */
volatile uint32_t cycleCount;

/* Function prototypes */
extern void initSignal(void);

void main(void)
{
    msp_status status;
    msp_max_q15_params maxParams;
    
    /* Disable WDT. */
    WDTCTL = WDTPW + WDTHOLD;

#ifdef __MSP430_HAS_PMM__
    /* Disable GPIO power-on default high-impedance mode for FRAM devices */
    PM5CTL0 &= ~LOCKLPM5;
#endif

    /* Initialize input signal */
    initSignal();
    
    /* Initialize the parameter structure. */
    maxParams.length = SAMPLES;
    
    /* Invoke the msp_max_q15 API. */
    msp_benchmarkStart(MSP_BENCHMARK_BASE, 1);
    status = msp_max_q15(&maxParams, input, &q15MaxVector, &uint16MaxIndex);
    cycleCount = msp_benchmarkStop(MSP_BENCHMARK_BASE);
    msp_checkStatus(status);
    
    /* End of program. */
    __no_operation();
}

void initSignal(void)
{
    msp_status status;
    msp_sinusoid_q15_params sinParams;

    /* Generate Q15 input signal */
    sinParams.length = SAMPLES;
    sinParams.amplitude = _Q15(SIGNAL_AMPLITUDE);
    sinParams.cosOmega = _Q15(cosf(2*PI*SIGNAL_FREQUENCY/FS));
    sinParams.sinOmega = _Q15(sinf(2*PI*SIGNAL_FREQUENCY/FS));
    status = msp_sinusoid_q15(&sinParams, input);
    msp_checkStatus(status);
}