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Although the SPI Relay driver is RC2014-specific, the SD Card driver is generic enough to be a subsystem. That's the second subsystem we add and this warrants, I think, the formalization of a new concept: protocols.
17 lines
743 B
Plaintext
17 lines
743 B
Plaintext
: _err (spid) ABORT" SDerr" ;
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( Tight definition ahead, pre-comment.
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Initialize a SD card. This should be called at least 1ms
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after the powering up of the card. We begin by waking up the
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SD card. After power up, a SD card has to receive at least
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74 dummy clocks with CS and DI high. We send 80.
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Then send cmd0 for a maximum of 10 times, success is when
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we get 0x01. Then comes the CMD8. We send it with a 0x01aa
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argument and expect a 0x01aa argument back, along with a
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0x01 R1 response. After that, we need to repeatedly run
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CMD55+CMD41 (0x40000000) until the card goes out of idle
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mode, that is, when it stops sending us 0x01 response and
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send us 0x00 instead. Any other response means that
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initialization failed. )
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