/*
* This function synchronously waits any pending block transfers
* are finished. If your program needs to ensure a block has finished
* transferring, call this function.
*
* Note that sd_read_block() and sd_write_block() already call this
* function internally before attempting a new transfer, so there are
* only two times when a user would need to use this function.
*
* 1) When the processor will be shutting down. All pending
* writes should be finished first.
* 2) When the user needs the result of an sd_read_block() call
* right away.
*/
void sd_wait_notbusy(sd_context_t *sdc)
{
/* Just twiddle our thumbs until the transfer's done */
while ((DMA0CTL & DMAEN) != 0);
/* Reset the DMA controller */
DMACTL0 = 0;
/* Ignore the checksum */
sd_delay(4);
/* Check for the busy flag (set on write block) */
if (sdc->busyflag == 1) {
while (spi_recv_byte() != 0xFF);
sdc->busyflag = 0;
}
/* Deassert CS */
spi_cs_deassert();
/*
* Send some extra clocks so the card can resynchronize
* on next transfer
*/
sd_delay(2);
}
//**********************************************************************************//
// Function Name: spi_recv_data //
// Arguments : U8 *data, U16 no_bytes //
// Return Types : NONE //
// Description : Function to receive no of bytes from slave specified by //
// "U16 no_byte" the argument & are stored in "U8 *data" //
//**********************************************************************************//
void spi_recv_data(U8 *data, U16 no_byte)
{
U16 temp_count;
for(temp_count = 0; temp_count < no_byte; temp_count++)
{
*data = spi_recv_byte();
data++;
}
}
/*
* This function writes a single block to the SD card at block
* blockaddr. Returns 1 if the command was successful, zero
* otherwise.
*
* This is an ASYNCHRONOUS call. The transfer will not be complete
* when the function returns. If you want to explicity wait until
* any pending transfer are finished, use the function
* sd_wait_notbusy(sdc)
*
* sd_context_t *sdc -- A pointer to an sd device context structure,
* populated by the function sd_initialize()
* u32 blockaddr -- The block address to write to the card.
* This is a block address, not a linear address.
* unsigned char *data -- The data, a pointer to an array of unsigned
* chars.
*/
int sd_write_block(sd_context_t *sdc, u32 blockaddr,
unsigned char *data)
{
/* Adjust the block address to a linear address */
blockaddr <<= SD_BLOCKSIZE_NBITS;
/* Wait until any old transfers are finished */
sd_wait_notbusy(sdc);
/* Pack the address */
sd_packarg(argument, blockaddr);
if (sd_send_command(sdc, CMD24, CMD24_R, response, argument) == 0)
return 0;
/* Check for an error, like a misaligned write */
if (response[0] != 0)
return 0;
/* Re-assert CS to continue transfer */
spi_cs_assert();
/*
* The write command need an addition 8 lock cycles before the
* block write is started
*/
spi_recv_byte();
/* Clear any pending flags */
IFG1 &= ~(URXIFG0 | UTXIFG0);
/* Get the block */
/* Source DMA address: receive register */
DMA0SA = (unsigned int)data;
/* Destination DMA address: the user data buffer */
DMA0DA = U0TXBUF_;
/* The size of the block to be transfered */
DMA0SZ = SD_BLOCKSIZE;
/* Configure the DMA transfer */
DMA0CTL =
DMADT_0 | /* Single transfer mode */
DMASBDB | /* Byte mode */
DMAEN | /* Enable DMA */
DMADSTINCR1 | DMADSTINCR0; /* Increment the destination address */
/* DMA trigger UART send */
DMACTL0 = DMA0TSEL_3;
/* Kick off transfer by sending the first byte */
U0TXBUF = SD_TOK_WRITE_STARTBLOCK;
/*
* Signal that the card may be busy, so any subsequent commands
* should wait for the busy signalling to end (indicated by a
* nonzero response)
*/
sdc->busyflag = 1;
return 1;
}
/*
* This function reads a single block from the SD card at block
* blockaddr. The buffer must be preallocated. Returns 1 if the
* command was successful, zero otherwise.
*
* This is an ASYNCHRONOUS call. The transfer will not be complete
* when the function returns. If you want to explicity wait until
* any pending transfer are finished, use the function
* sd_wait_notbusy(sdc)
*
* sd_context_t *sdc -- A pointer to an sd device context structure,
* populated by the function sd_initialize()
* u32 blockaddr -- The block address to read from the card.
* This is a block address, not a linear address.
* unsigned char *data -- The data, a pointer to an array of unsigned
* chars.
*/
int sd_read_block(sd_context_t *sdc, u32 blockaddr,
unsigned char *data)
{
u32 i = 0;
unsigned char tmp;
/* Adjust the block address to a linear address */
/* blockaddr <<= SD_BLOCKSIZE_NBITS; */
/* Wait until any old transfers are finished */
sd_wait_notbusy(sdc);
/* Pack the address */
sd_packarg(argument, blockaddr);
/* Need to add size checking */
if (sd_send_command(sdc, CMD17, CMD17_R, response, argument) == 0)
return 0;
/* Check for an error, like a misaligned read */
if (response[0] != 0)
return 0;
/* Re-assert CS to continue the transfer */
spi_cs_assert();
/* Wait for the token */
i = 0;
do {
tmp = spi_recv_byte();
i++;
} while ((tmp == 0xFF) && i < sdc->timeout_read);
if ((tmp & MSK_TOK_DATAERROR) == 0) {
/* Clock out a byte before returning */
spi_send_byte(0xFF);
/* The card returned an error response. Ball and return 0 */
return 0;
}
IFG1 &= ~URXIFG0;
IFG1 &= ~UTXIFG0;
/* Get the block */
/* Source DMA address: receive register */
DMA0SA = U0RXBUF_;
/* Destination DMA address: the user data buffer */
DMA0DA = (unsigned int)data;
/* The size of the block to be transfered */
DMA0SZ = SD_BLOCKSIZE;
/* Configure the DMA transfer */
DMA0CTL =
DMADT_0 | /* Single transfer mode */
DMASBDB | /* Byte mode */
DMAEN | /* Enable DMA */
DMADSTINCR1 | DMADSTINCR0; /* Increment the destination address */
/*
* We depend on the DMA priorities here. Both triggers occur at
* the same time, sine the source is identical. DMA0 is handled
* first, and retrieves the byte. DMA1 is triggered next, and
* sends the next byte.
*/
/* Source DMA address: constant 0xFF (don't increment) */
DMA1SA = (unsigned int)␣
/* Destination DMA address: the transmit buffer */
DMA1DA = U0TXBUF_;
/* Increment the destination address */
/* The size of the block to be transfered */
DMA0SZ = SD_BLOCKSIZE - 1;
/* Configure the DMA transfer */
DMA1CTL =
DMADT_0 | /* Single transfer mode */
DMASBDB | /* Byte mode */
DMAEN; /* Enable DMA */
/* DMA trigger UART receive for both DMA0 and DMA1 */
DMACTL0 = DMA0TSEL_3 | DMA1TSEL_3;
/* Kick off transfer by sending the first byte */
U0TXBUF = 0xFF;
return 1;
}