Table 171. Speed Class Code Field - ST STM32F412 Reference Manual

Secure digital input/output interface (SDIO)
Bits Identifier
PERFORMANCE_
439: 432
MOVE
431:428 AU_SIZE
427:424 Reserved
423:408 ERASE_SIZE
407:402 ERASE_TIMEOUT S R
401:400 ERASE_OFFSET
399:312 Reserved
311:0 Reserved for Manufacturer
SIZE_OF_PROTECTED_AREA
Setting this field differs between standard- and high-capacity cards. In the case of a
standard-capacity card, the capacity of protected area is calculated as follows:
Protected area = SIZE_OF_PROTECTED_AREA_* MULT * BLOCK_LEN.
SIZE_OF_PROTECTED_AREA is specified by the unit in MULT*BLOCK_LEN.
In the case of a high-capacity card, the capacity of protected area is specified in this field:
Protected area = SIZE_OF_PROTECTED_AREA
SIZE_OF_PROTECTED_AREA is specified by the unit in bytes.
SPEED_CLASS
This 8-bit field indicates the speed class and the value can be calculated by P
P is the write performance).
W
00h
01h
02h
03h
04h – FFh
892/1163
Table 170. SD status (continued)
Type
Performance of move indicated by
1 [MB/s] step.
S R
(See below)
Size of AU
S R
(See below)
Number of AUs to be erased at a
S R
time
Timeout value for erasing areas
specified by
UNIT_OF_ERASE_AU
Fixed offset value added to erase
S R
time.

Table 171. Speed class code field

SPEED_CLASS
Value
Class 0
Class 2
Class 4
Class 6
Reserved
RM0402 Rev 6
Description
(See below)
(See below)
(See below)
(See below)
(See below)
Value definition
RM0402
Clear
condition
A
A
A
A
A
/2 (where
W