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Hi, I'm trying to communicate with a SD card on SD bus. now,I read manual LPC23xx in chapter SD/MMC card and Data sheet sandisk SD card.is it enough? Have you got any suggestion to me(or for read)? Have you got any simple piece of software that configure the card. I don't know what to do first? Thank you...
popo+
"one clock line, one MOSI (Master Out Slave In) and one MISO (Master In Slave Out)."
and, in some cases (including the SD card), a Slave-Select (SS) line.
aka "Chip Select".
Yes, a slave select is needed for the slave side to be able to synchronize the bit sequence.
However, a number of SPI controllers do not have a dedicated slave-select signal in master mode and requires you to use a normal GPIO signal. For slave mode, the controller should have a dedicated slave-select line.
Requiring the master to use GPIO signals instead of a dedicated slave-select pin allows the master to have multiple slaves connected. The master may then select which slave to communicate with. And if only the MOSI signal is used, i.e. no data is sent from slave to master, then the master may activate multiple slave-select signals and send the same information to multiple slaves.