Posted on March 10, 2012 at 14:26I really can't understand what kind of driver you are speaking and looking for.
SPI is the simpliest communication protocol, especially without DMA.
what do you need to drive SD by SPI:
HW
1) properly connect signal lines MOSI,MISO,SCLK (and SS or any GPIO for SD CS)
2) Set pullup resistors (at least to MOSI and MISO lines), optionally decoupling capacitor between power lines close to card
SW
1) initialize SPI with a standard peripheral driver
2) enable SPI
Then, select SD.
To write data to :
1) SD_SPI -> DR = data;
wait for the end of transmission:
2) while (SPI_I2S_GetFlagStatus(SD_SPI, SPI_I2S_FLAG_TXE) == RESET);
when all bytes send wait for BSY flag:
3) while (SPI_I2S_GetFlagStatus(SD_SPI, SPI_I2S_FLAG_BSY) == SET);
4)deselect SD.
If you don't use the highest speed, you can skip waiting for BSY flag and even TXE. But better keep them at place.
To read data from SD:
Send dummy byte:
1) SD_SPI -> DR = 0xff;
wait for the end of transmission:
2) while (SPI_I2S_GetFlagStatus(SD_SPI, SPI_I2S_FLAG_RXNE) == RESET);
get the data:
data = SD_SPI -> DR;
if needed, check BSY flag.
That's all.
Due to SD is a block device, I showed some macros for FATFS to read from/write to SD in my previous post.
But what does your valuable driver do?
