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Working on programming AVR chips exposes a glaring omission in my first design of the SPI Relay: not allowing multiple devices make this task hard. I constantly have to unplug my SD card before, plug the AVR chip holder, then play a bit, then unplug the AVR holder, then replug the SD card... My prototype for a SPI relay design is built, but I haven't tested it yet. I need to adapt the code first, which is what I do here. When the prototype is tested, I'll update the SDC recipe with a new schema.
17 lines
745 B
Plaintext
17 lines
745 B
Plaintext
: _err 0 (spie) 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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