AT88SC0104CA_08 Datasheet, PDF (48/58 Pages) ATMEL Corporation – CryptoMemory Specification for Standard Mode of Operation

AT88SCXXXXCA
9.5 System READ: $B6
9.5.1
Functional
System Read Command Functional Description
Host
Device
Read Command
Address 1
Address 2
Number of bytes N
Data
...
Data
N data bytes
The System Read command allows reading of system data from the device. Depending on the
value of the P1 parameter, the host may read the data in the configuration zone, or the fuses.
Table 9-6. System Read Command Detail
Command
CLA
INS
P1
P2
P3
Read Config Zone
$00
$B6
$00
addr
N
Read Fuse Byte
$00
$B6
$01
$00
$01
Data (N)
9.5.2
Read Config Zone
To read 256 bytes, the host should set N = $00. This is true for any outgoing command, and is
defined by ISO 7816-3. If the address provided at P2 is an unauthorized address, the device will
return the "Command Unauthorized" code ($69 $00) after it has received the header. Since
access rights vary throughout the configuration zone, the host may provide an authorized start-
ing address, but a number of bytes N that causes the device to reach unauthorized data. In this
case, the device will transmit the authorized bytes, but unauthorized bytes will be replaced by
the "fuse byte" (see below). At the end of this command the "Command Unauthorized" code
($69 $00) will be returned instead of $90 $00 to indicate that some of the bytes returned are not
valid.
9.5.3
Read Fuse Byte
Fuse data is returned in the form of a single byte. Bits 0 to 3 represent the fuse states; a value of
‘0’ indicates the fuse has been blown. Bits 4 to 7 are not used as Security Fuses and are
reserved by Atmel.
Figure 9-7. Fuse Byte Bit-Map
F₇
resv
F₆
resv
F₅
resv
F₄
resv
F₃
SEC
Figure 9-8. System Read Command Structure
Command Header
CLA INS : Command
**
$B6
P1
p7--- ---p0
P2
p7--- ---p0
P3
n7--- ---n0
F₂
PER
F₁
CMA
F₀
FAB
Data Returned
Data(1)
... Data(N)
d7--- ---d0 ... d7--- ---d0
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