// read a size Byte big block beginning at the address.
char mmcReadBlock(const unsigned long address, const unsigned long count, unsigned char *pBuffer) {
char rvalue = MMC_RESPONSE_ERROR;
// Set the block length to read
if (mmcSetBlockLength (count) == MMC_SUCCESS) { // Attempt to set block length
MMC_CS_LOW ();
// send read command MMC_READ_SINGLE_BLOCK=CMD17
mmcSendCmd (MMC_READ_SINGLE_BLOCK,address, 0xFF);
// Send 8 Clock pulses of delay, check if the MMC acknowledged the read block command
// it will do this by sending an affirmative response
// in the R1 format (0x00 is no errors)
if (mmcGetResponse() == 0x00) {
// Look for the data token to signify the start of data
if (mmcGetXXResponse(MMC_START_DATA_BLOCK_TOKEN) == MMC_START_DATA_BLOCK_TOKEN) {
// Clock the actual data transfer and receive the bytes; spi_read automatically finds the Data Block
spiReadFrame(pBuffer, count);
// Get CRC bytes (not really needed by us, but required by MMC)
spiSendByte(DUMMY_CHAR);
spiSendByte(DUMMY_CHAR);
rvalue = MMC_SUCCESS;
}
else { // The data token was never received
rvalue = MMC_DATA_TOKEN_ERROR; // 3
}
}
else { // The MMC never acknowledge the read command
rvalue = MMC_RESPONSE_ERROR; // 2
}
}
else { // The block length was not set correctly
rvalue = MMC_BLOCK_SET_ERROR; // 1
}
MMC_CS_HIGH ();
spiSendByte(DUMMY_CHAR);
return rvalue;
}// mmc_read_block
void main(void) {
//Turn off the watchdog timer
WDTCTL = WDTPW + WDTHOLD;
P1DIR |= LED;
P1OUT &= ~LED;
//16MHz
//Set DCO to 16 MHz calibrated
DCOCTL = CALDCO_16MHZ;
BCSCTL1 = CALBC1_16MHZ;
//Reset SD card by cycling power
//Credit to Boris Cherkasskiy and his blog post on Launchpad+MMC
P2DIR |= BIT2;
P2OUT &= ~BIT2;
__delay_cycles(1600000); // 100ms @ 16MHz
P2OUT |= BIT2;
__delay_cycles(1600000); // 100ms @ 16MHz
//Initialize MMC library
while (MMC_SUCCESS != mmcInit());
//Verify card ready
while (MMC_SUCCESS != mmcPing());
//Check the memory card size
volatile unsigned long size = mmcReadCardSize();
//Toggle the LED to indicate that reading was successful
P1OUT ^= LED;
//Test that the SD card is working
//Read in the OEM name and version in bytes 3-10
volatile unsigned char block[64] = {0};
// Read in a 512 byte sector
// This is a multipart process.
// First you must mount the block, telling the SD card the relative offset
// of your subsequent reads. Then you read the block in multiple frames.
// We do this so we don't need to allocate a full 512 byte buffer in the
// MSP430's memory. Instead we'll use smaller 64 byte buffers. This
// means that an entire block will take 8 reads. The spiReadFrame command
// reads in the given number of bytes into the byte array passed to it.
// After reading all of the data in the block it should be unmounted.
//volatile char result = mmcReadBlock(0, 64, block);
//volatile char result = mmcMountBlock(0, 512);
volatile char result = mmcMountBlock(0, 512);
//My FAT partition apparently starts at block 129 (0x81)
//If you have a FAT16 filesystem you could read data from that point
//Read in the block 64 bytes at a time
if (result == MMC_SUCCESS) {
volatile int i = 0;
//8 blocks of 64 to read
for (i = 0; i < 8; ++i) {
//If you set a breakpoint here you can examine the memory in the card.
spiReadFrame((void*)block, 64);
}
mmcUnmountBlock();
}
while (1);
}
