| ??? 11/13/05 13:41 Read: times |
#103653 - SD command structure Responding to: ???'s previous message |
Jeff Corr said:
I'd assume a simple loop by loading the Acc with a command and clocking it out with rotate to carry would be how to clock it out, im simply not sure of the formats it expects. Yes. Look at the source code for SBCMON for an SPI routine. Does it expect ascii values coming in? How are they formatted? You may refer to this document. It has a list of all the commands. Note that the list of commands differs between SD mode and SPI mode so make sure you're looking at the right list. Commands are 6-byte binary sequences that consist of a command byte followed by 4 data bytes followed by a CRC byte. Bit 7 of the command byte is always clear and bit 6 is always set. That means that CMD00, for example, is 0x40. Also, what would you use to interface 5V logic levels to 2.7V logic levels? Is there an IC that does this? You can use something like a '125, which is open-drain, to convert between 5V and some other voltage level. Also note that SD cards may operate at between 2.7V and 3.6V. Regards, Craig Steiner |
| Topic | Author | Date |
| SDcards and filesystems | 01/01/70 00:00 | |
| Some SD/FAT answers | 01/01/70 00:00 | |
| no FS | 01/01/70 00:00 | |
| Also... | 01/01/70 00:00 | |
| Even more... anybody got any ideas? | 01/01/70 00:00 | |
| SD command structure | 01/01/70 00:00 | |
| datasheet | 01/01/70 00:00 | |
| SD card communication | 01/01/70 00:00 | |
| transmission block | 01/01/70 00:00 | |
| Push | 01/01/70 00:00 | |
| Won't work | 01/01/70 00:00 | |
| CRC | 01/01/70 00:00 | |
| Thats called a file system | 01/01/70 00:00 | |
Look Here | 01/01/70 00:00 |