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Code: Select all

for ( uint32_t i = 0 ; i < 15360 ; i++ )
{        
    buffer_a[i].full = 0xFF00;  // FF byte more significant.  00 byte less significant.
}

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static void dma_tx_reset( )
{   
    I2SX.lc_conf.out_rst = 1;    // Set this bit to reset out DMA FSM. (R/W)
    I2SX.lc_conf.out_rst = 0;    // FSM = Finite State Machine.
}

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uint16_t buffer_a[15360];  // the correct buffer size value is 3840 uint16_t, but this has no influence beyond memory waste.

for ( uint32_t i = 0 ; i < 15360 ; i++ )
{        
    buffer_a[i] = 0xFF00;  // FF most significant byte. 00 least significant byte.
}    

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void i2s_reset(void)
{
        I2SX.conf.tx_reset = 1;
        I2SX.conf.tx_reset = 0;
}

Code: Select all

int i2s_lcd_write_data ( uint32_t length, bool buffer_id )  // length = number in bytes. length <= 7680.
{
    static uint32_t i;
    static uint8_t* ptr = NULL; 


    if ( length > pixels_size_in_bytes )    // Length > buffer capacity. pixels_size_in_bytes = 7680 bytes. 
    {
        printf( "Error: length > %d. \n\n", pixels_size_in_bytes );
        return -1;
    }     

    
    if ( buffer_id == 0 )    
    {   
        ptr = (uint8_t *) &buffer_a;    // buffer_a is uint16_t.

        /*
        printf( "\n&buf_a = %p\n", &buf_a );
        printf( "&buffer_a = %p\n", &buffer_a );
        printf( "ptr = %p\n\n", ptr );
        */

        for ( i = 0 ; i < length ; i = i + 2 )    // length <= 7680 bytes.  loop max 7680/2 = 3840 times.
        {        
            buf_a[ i ] = ptr[ i ];    // The address of buf_a increment in 4 bytes while the address of buffer_a(ptr) increment in 1 byte.
            buf_a[ i + 1 ] = ptr[ i + 1 ];

            /*           
            printf( "&ptr[ %d ] = %p\n", i, &ptr[ i ] );
            printf( "ptr[ %d ] = 0x%02X\n", i, ptr[ i ] );

            printf( "&ptr[ %d ] = %p\n", i+1, &ptr[ i+1 ] );
            printf( "ptr[ %d ] = 0x%02X\n", i+1, ptr[ i+1 ] );

            printf( "&buf_a[ %d ] = %p\n", i, &buf_a[ i ] );      
            printf( "buf_a[ %d ] = 0x%08X\n", i,  buf_a[ i ] );

            printf( "&buf_a[ %d ] = %p\n", i+1, &buf_a[ i+1 ] );
            printf( "buf_a[ %d ] = 0x%08X\n", i+1,  buf_a[ i+1 ] );           

            printf("\n");
            */
        }
    
        fill_dma_descriptor_a( (uint32_t) 4 * length );               // ( 4 * length ) = change from byte(8 bits) to word(32bits). 
        I2SX.out_link.addr = (uint32_t) &dma_desc_buf_a[0];    // ( (uint32_t) ( &dma_desc_buf_a[0] ) ) & I2S_OUTLINK_ADDR;  
    }
    else
    {
        ptr = (uint8_t *) &buffer_b;   

        for ( i = 0 ; i < length ; i = i + 2 )    
        {        
            buf_b[ i ] = ptr[ i ];    
            buf_b[ i + 1 ] = ptr[ i + 1 ];
        }         
         
        fill_dma_descriptor_b( (uint32_t) 4 * length );  
        I2SX.out_link.addr = (uint32_t) &dma_desc_buf_b[0];
    }


    I2SX.out_link.start = 1;          // Set this bit to start outlink descriptor. (R/W).
    I2SX.fifo_conf.dscr_en = 1;    // Set this bit to enable I2S DMA mode. (R/W).   
    I2SX.conf.tx_start = 1;          // Set this bit to start transmitting data. (R/W).  
    
    
    while ( ! ( I2SX.state.tx_idle ) )   // The status bit of the transmitter. 1: the transmitter is idle. 0: the transmitter is busy.(RO)
    { }
    

    I2SX.conf.tx_start = 0;           // Set this bit to start transmitting data. (R/W).    
    I2SX.fifo_conf.dscr_en = 0;    // Set this bit to enable I2S DMA mode. (R/W).


    tx_reset( );            // Set this bit to reset the transmitter. (R/W)
    dma_tx_reset( );    // Set this bit to reset out DMA FSM. FSM = Finite State Machine. (R/W)

/*
    I2SX.lc_conf.ahbm_rst = 1; 
    I2SX.lc_conf.ahbm_rst = 0;
    
    I2SX.lc_conf.ahbm_fifo_rst = 1;
    I2SX.lc_conf.ahbm_fifo_rst = 0;
*/

    return 2019;
}