main.c

Audio output from sound file for MCU.

/*=============================================================================
Cyan Technology Limited

FILE - main.c

DESCRIPTION
    WAVE file playing and storage.
    This software is designed to be used to allow external sound files
    in raw sample format to be loaded into the eCOG via the UART and played
    from an external memory. The output is generated using PWM and requires
    external filtering and amplification.
    
    We will attempt to put the whole SDRAM to use, using 0x8000 byte chunks
    requiring 512 banks to be mapped independently
    
    To Do:
        Add option for stereo using PWM2

    Tony Ward - March 2005

=============================================================================*/

#include <ecog.h>
#include <ecog1.h>
#include <stdio.h>
#include <math.h>
#include <string.h>
#include "driver_lib.h"

int uart_wav_read (void);
int uart_input_check (char *);
int flipend (int);

unsigned int *rloc;                // Current record location
unsigned int *ploc;                // Current play location
int pbank, rbank;                  // Memory 'bank' number
int tv, a;                         // Temporary variables

int main(int argc, char* argv[])
{
    char input;
    int sts = 0;    // Status flag
    
    ssm_pwm1_clk(SSM_HIGH_PLL, 0);      // Maximum speed
    fd.tim.ctrl_en.pwm1_auto_re_ld = 1; // Turn on automatic reload
    rg.tim.pwm1_ld = 565;               // PWM load value
    rg.tim.pwm1_val = 228;              // Default PWM change value = 50%
    
    fd.emi.ctrl_sts.refr_en = 1;        // SDRAM hack to enable refresh

    // Initialise the record and play pointers
    rloc = (unsigned int *) 0x0000;
    ploc = (unsigned int *) 0x0000;
    
    duart_a_tx(':');    // Indicate working
    
    while(1)
    {
        // Poll the UART and act on any received data
        if (1 == fd.duart.a_sts.rx_1b_rdy)
        {
            input = rg.duart.a_rx & 0xff;
            switch (input)
            {
                case ('l'):             // Load and play a wav file from UART
                // sts will be 0 for complete, 1 for end memory or else 2
                duart_a_tx('L');         // Display 'L'
                sts = uart_wav_read();  // Run subroutine to read WAV file
                duart_a_tx(sts + 48);   // Transmit the return status
                break;

                case ('s'): // stop
                duart_a_tx('S');
                fd.tim.int_dis1.pwm1_exp = 1;     // stop the pwm
                fd.tim.ctrl_dis.pwm1_cnt = 1;
                pbank = 0;        // Reset the playback bank
                break;

                case ('p'): // play
                duart_a_tx('P');
                // Map in the correct memory first
                rg.mmu.ext_cs0_data0_phy = (pbank * 0x0080);
                fd.tim.int_en1.pwm1_exp = 1;    // Enable interrupt
                fd.tim.ctrl_en.pwm1_cnt = 1;    // Start the PWM
                break;
            }
        }
    }
    
    return (0);
}


/*================================================================================
  WAVE read functions
================================================================================*/

// Function for receiving wav file to memory via the UART
int uart_wav_read (void) 
{
    unsigned long datasize;       // Size of incoming wav file
    unsigned long icount;         // Input and output count variable
    
    datasize = 500000;            // Explicit for now
    icount = 0;
    while (icount++ != datasize)        // Loop till end of memory/file    
    {    
        while (!fd.duart.a_sts.rx_2b_rdy | fd.duart.a_sts.rx_act) 
            ;                           // Wait for sample and frame
        *rloc++ = (rg.duart.a_rx);      // use flipend here if needed
        if (rloc == ((unsigned int *) 0x4000))    // End of bank reached
        {
            // Set location to beginning of bank
            rloc = ((unsigned int *) 0x0000);    
            rbank++;                    // Increment current bank number
            if (rbank == 0x0200)        // This is the end of memory, stop
            {
                rbank = 0;              // Reset bank number
                return(1);
            }
            // We now need to remap the memory according to the bank number
            rg.mmu.ext_cs0_data0_phy = (rbank * 0x0080);
        }
    }
    return(0);
}


// Simple function to swap endianness of words if required
int flipend (int in)
{
    return(((in & 0x00ff) << 8) + ((in & 0xff00) >> 8));
}


/*================================================================================
  Interrupt service routines (ISRs)
================================================================================*/

void __irq_entry pwm_handler (void)
{
    unsigned int sample_val;
    
    fd.tim.int_clr1.pwm1_exp = 1;       // Clear the interrupt
    // We assume here that the sample is properly scaled to max PWM period length
    sample_val = (*ploc++);             // Get sample from memory
    rg.tim.pwm1_val = (sample_val);     // Output sample on PWM
    
    // Now check and set the bank number if necessary
    if (ploc == (unsigned int *) 0x4000)    // End of current bank reached
    {
        ploc = (unsigned int *) 0x0000;     // Set location to beginning of bank
        pbank++;                            // Increment current bank number
        if (pbank == 0x0200)                // This is the end of memory, stop
        {
            pbank = 0;                      // Reset bank number
            fd.tim.int_dis1.pwm1_exp = 1;   // Turn off this interrupt
        }
        // We now need to remap the memory according to the bank number
        rg.mmu.ext_cs0_data0_phy = (pbank * 0x0080);
    }
}