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/*************************************************************************************
DEPARTMENT OF ELECTRICAL AND ELECTRONIC ENGINEERING
IMPERIAL COLLEGE LONDON
EE 3.19: Real Time Digital Signal Processing
Dr Paul Mitcheson and Daniel Harvey
LAB 2: Learning C and Sinewave Generation
********* S I N E . C **********
Demonstrates outputing data from the DSK's audio port.
Used for extending knowledge of C and using look up tables.
*************************************************************************************
Updated for use on 6713 DSK by Danny Harvey: May-Aug 06/Dec 07/Oct 09
CCS V4 updates Sept 10
************************************************************************************/
/*
* Initialy this example uses the AIC23 codec module of the 6713 DSK Board Support
* Library to generate a 1KHz sine wave using a simple digital filter.
* You should modify the code to generate a sine of variable frequency.
*/
/**************************** Pre-processor statements ******************************/
// Included so program can make use of DSP/BIOS configuration tool.
#include "dsp_bios_cfg.h"
/* The file dsk6713.h must be included in every program that uses the BSL. This
example also includes dsk6713_aic23.h because it uses the
AIC23 codec module (audio interface). */
#include "dsk6713.h"
#include "dsk6713_aic23.h"
// math library (trig functions)
#include <math.h>
// Some functions to help with configuring hardware
#include "helper_functions_polling.h"
// PI defined here for use in your code
#define PI 3.141592653589793
// Contains the size of the sine table
#define SINE_TABLE_SIZE 256
/******************************* Global declarations ********************************/
/* Audio port configuration settings: these values set registers in the AIC23 audio
interface to configure it. See TI doc SLWS106D 3-3 to 3-10 for more info. */
DSK6713_AIC23_Config Config = { \
/**********************************************************************/
/* REGISTER FUNCTION SETTINGS */
/**********************************************************************/\
0x0017, /* 0 LEFTINVOL Left line input channel volume 0dB */\
0x0017, /* 1 RIGHTINVOL Right line input channel volume 0dB */\
0x01f9, /* 2 LEFTHPVOL Left channel headphone volume 0dB */\
0x01f9, /* 3 RIGHTHPVOL Right channel headphone volume 0dB */\
0x0011, /* 4 ANAPATH Analog audio path control DAC on, Mic boost 20dB*/\
0x0000, /* 5 DIGPATH Digital audio path control All Filters off */\
0x0000, /* 6 DPOWERDOWN Power down control All Hardware on */\
0x004f, /* 7 DIGIF Digital audio interface format 32 bit */\
0x008d, /* 8 SAMPLERATE Sample rate control 8 KHZ */\
0x0001 /* 9 DIGACT Digital interface activation On */\
/**********************************************************************/
};
// Codec handle:- a variable used to identify audio interface
DSK6713_AIC23_CodecHandle H_Codec;
/* Sampling frequency in HZ. Must only be set to 8000, 16000, 24000
32000, 44100 (CD standard), 48000 or 96000 */
int sampling_freq = 16000;
// Array of data used by sinegen to generate sine. These are the initial values.
float y[3] = {0,0,0};
float x[1] = {1}; // impulse to start filter
float a0 = 1.4142; // coefficients for difference equation
float b0 = 0.707;
// Holds the value of the current sample
float sample;
/* Left and right audio channel gain values, calculated to be less than signed 32 bit
maximum value. */
Int32 L_Gain = 2100000000;
Int32 R_Gain = 2100000000;
/* Use this variable in your code to set the frequency of your sine wave
be carefull that you do not set it above the current nyquist frequency! */
float sine_freq = 1000.0;
// Declares the global sine table that will be used to generate the sine wave
float table[SINE_TABLE_SIZE];
// Current index in the table, that can be used to calculate the next index
int sine_index = 0;
/******************************* Function prototypes ********************************/
void init_hardware(void);
void sine_init(void);
float sinegen(void);
/********************************** Main routine ************************************/
void main()
{
// initialize board and the audio port
init_hardware();
// Initialize the sine table
sine_init();
// Loop endlessley generating a sine wave
while(1)
{
// Calculate next sample
sample = sinegen();
/* Send a sample to the audio port if it is ready to transmit.
Note: DSK6713_AIC23_write() returns false if the port if is not ready */
// send to LEFT channel (poll until ready)
while (!DSK6713_AIC23_write(H_Codec, ((Int32)(sample * L_Gain))))
{};
// send same sample to RIGHT channel (poll until ready)
while (!DSK6713_AIC23_write(H_Codec, ((Int32)(sample * R_Gain))))
{};
// Set the sampling frequency. This function updates the frequency only if it
// has changed. Frequency set must be one of the supported sampling freq.
set_samp_freq(&sampling_freq, Config, &H_Codec);
}
}
/******************************* init_hardware() ************************************/
void init_hardware()
{
// Initialize the board support library, must be called first
DSK6713_init();
// Start the codec using the settings defined above in config
H_Codec = DSK6713_AIC23_openCodec(0, &Config);
/* Defines number of bits in word used by MSBSP for communications with AIC23
NOTE: this must match the bit resolution set in in the AIC23 */
MCBSP_FSETS(XCR1, XWDLEN1, 32BIT);
/* Set the sampling frequency of the audio port. Must only be set to a supported
frequency (8000/16000/24000/32000/44100/48000/96000) */
DSK6713_AIC23_setFreq(H_Codec, get_sampling_handle(&sampling_freq));
}
/******************************* sin_init() ************************************/
void sine_init()
{
int i;
for(i = 0; i < SINE_TABLE_SIZE; i++)
{
table[i] = sin(2 * PI * i / SINE_TABLE_SIZE);
}
}
/********************************** sinegen() ***************************************/
float sinegen(void)
{
// temporary variable used to output values from function
float wave;
wave = table[(int)((sine_freq / (float)sampling_freq) * (float)SINE_TABLE_SIZE * sine_index) % SINE_TABLE_SIZE];
sine_index++;
return(wave);
}
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