pwm.h

MP3 Cyclone的source code 利用FPGGA實現MP3的功能

/***********************************************************************
 *                                                                     *
 * File:     pwm.h                                                     *
 *                                                                     *
 * Purpose:  Provides an API to play audio through the PWM with FIFO   *
 *           SOPC Builder Component                                    *
 *                                                                     *
 * Author: N. Knight                                                   *
 *         Altera Corporation                                          *
 *         Aug 2005                                                    *
 **********************************************************************/

#ifndef _PWM_H_
#define _PWM_H_

#include "alt_types.h"

/*
 * Clock rate of the PWM.  Important for calculating sample rates.
 * Can be independent of the system clock rate
 */
#  define PWM_CLOCK_RATE 112500000 //112.500000 MHz
//#define PWM_CLOCK_RATE 128571429 //128.571429 MHz
//#define PWM_CLOCK_RATE 133332000 //133.332000 MHz
//#define PWM_CLOCK_RATE 150000000 //150.000000 MHz


/* Register map of PWM with FIFO peripheral */
#define PWM_CONTROL_OFFSET 0x0
#define PWM_FIFO_USED_OFFSET 0x4
#define PWM_PERIOD_OFFSET 0x8
#define PWM_DATA_OFFSET 0xC

/* PWM control register values */
#define PWM_STOP 0
#define PWM_GO 1
#define PWM_RESET 2

/* Return values */
#define SUCCESS 0
#define FAIL -1

/* Sets the sampling rate for playback... */
void PWM_SetSamplingRate( alt_u32 new_sample_rate, alt_u32 pwm_base_addr );

/* Plays a given number of samples */
int PWM_PlaySamples( int *left, int *right, alt_u32 num_samples, 
                           alt_u32 sample_period, alt_u32 fifo_size, 
                           alt_u32 pwm_base_addr );

/* Scales a sample for PWM */
int PWM_ScaleSample( int sample, int sampling_period );

/* Stops the playing of samples */
void PWM_Stop( alt_u32 pwm_base_addr );

/* Starts the playing of samples */
void PWM_Start( alt_u32 pwm_base_addr );

/* Reset the PWM, then return it to stopped state */
void PWM_ResetPWM( alt_u32 pwm_base_addr );

#endif /* _PWM_H_ */