Specifications

©Copyright 2001-2013 SD Group (Panasonic, SanDisk, Toshiba) and SD Card Association
Physical Layer Simplified Specification Version 4.10
105
by CMD20 Update CI)
Even if the write data size after CMD20 Update CI is wrong (larger than 512-byte), the card accepts
data writes without error but Speed Class performance is not maintained.
The SDXC Speed Class host shall issue CMD20 Update DIR before CMD20 Start Recording so that
the card can distinguish DIR and CI properly. Between Update DIR and Start Recording, data
read/write/erase commands and secure commands are allowed. In addition, read commands of
registers/status are also allowed.
If any other commands are issued, CMD20 Update DIR shall be issued again before CMD20 Start
Recording.
Figure 4-55 : Example of Speed Class Recording
Update
DIR
Write
DIR
Start
Rec
Write
CI
FAT
Update
Write
RU
Other
Write
Write
RU
.....
Other
Write
Update
DIR
Write
DIR
- Non-Speed Class write
- CI may be written after
the recording
"Update DIR" means
DIR for next stream
Always Issued before
Start Recording
(DIR address is used in the recording)
Always preceding the write command updating CI (Write CI)
(Need to be issued just before "Write CI")
Update
CI
Write
CI
Write Busy ~ 500ms Write Busy ~ 500msWrite Busy ~ 250ms
Speed Class Recording Period