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mwgilson · 04-02-09, 08:47 PM

I am not sure to what detail the members of this forum are aware of in regards to SD Cards, but I'm going to make this post regardless and see if anyone out there can answer it.

I am writing an SD Mode (not SPI Mode) core that reads and writes to an SD Card. I completed the initialization of the card, and I believe I can read from the card in 4-bit mode, but I am having a problem when writing to the card in 4-bit mode. When I write a 512 byte block of data (initiated by a CMD25 command), I tri-state the data bus, and see a command come back from the card. This command, from what I can tell from the Simplified Spec, is what is called a "CRC Status" byte. The Simplified Spec doesn't say what this is, except a start bit, several status bits, and an end bit. Simply put, my writes are not working, and I'd like to be able to interpret what this command is to find out why. If anyone out there could provide even the slightest assistance I would be greatful. Thank you.

04-02-09, 08:47 PM	#1 (permalink)
mwgilson Aximsite Prospect Join Date: Apr 2009 Posts: 1 Thanked 1 Time in 1 Post	SD Mode Reads/Writes I am not sure to what detail the members of this forum are aware of in regards to SD Cards, but I'm going to make this post regardless and see if anyone out there can answer it. I am writing an SD Mode (not SPI Mode) core that reads and writes to an SD Card. I completed the initialization of the card, and I believe I can read from the card in 4-bit mode, but I am having a problem when writing to the card in 4-bit mode. When I write a 512 byte block of data (initiated by a CMD25 command), I tri-state the data bus, and see a command come back from the card. This command, from what I can tell from the Simplified Spec, is what is called a "CRC Status" byte. The Simplified Spec doesn't say what this is, except a start bit, several status bits, and an end bit. Simply put, my writes are not working, and I'd like to be able to interpret what this command is to find out why. If anyone out there could provide even the slightest assistance I would be greatful. Thank you.