AT88SC0104CA_11 ATMEL [ATMEL Corporation], AT88SC0104CA_11 Datasheet - Page 35

• Manufacturer Part Number: AT88SC0104CA_11
• Description: Atmel CryptoMemory Specification Datasheet
• Manufacturer: ATMEL [ATMEL Corporation]

8.10.1.2 Write Fuses
8.10.1.3 Send Checksum
8.10.1.4 Set User Zone
The fuses may only be "programmed", that is written from '1' to '0'. The write fuses operation is allowed only after successfully
presenting the secure code (Write 7 password). The fuses must be blown sequentially: FAB must be blown first, CMA may be
blown only if FAB is ‘0’, and PER only if CMA is ‘0’. After this command the host must perform ACK polling. The SEC fuse is
blown at the Atmel factory to protect lot history information.
Table 8-4.
To write data to user zones that require authentication or encryption for write access (ER = “0”, AM[1:0] = “00”, “01”, or “10” in
the access register), the host should first carry out the write command $B0. At this point the memory is unchanged and the
device is waiting for the host to provide a valid checksum before initiating the write cycle. The host immediately sends the
checksum it has computed using the system write command with P1 = $02. Only if the checksum is valid will the device initiate
the write cycle. Furthermore, if the device receives an incorrect checksum, it will clear the authentication privilege. After this
command the host must perform ACK polling.
Before reading and writing data in the user zones, the host must select a zone with this command. At this time the host
chooses whether anti-tearing should be active for this zone.
Table 8-5.
Data written to the configuration zone may be done with anti-tearing enabled by setting Address 1 to $08 of the write
configuration zone command.
To enable anti-tearing for writes to a user zone, a set user zone command is executed with Address 1 set to $0B. All
subsequent write user zone commands will be executed with anti-tearing enabled until the next set user zone command.
Anti-tearing should be turned off if not required, as it would otherwise cause more write cycles than necessary
Figure 8-12. System Write Command Detail
S
A
R
T
T
Command Description
Write Config Zone with Anti-tearing
Set User Zone with Anti-tearing
Command
1011 0100
Fuse
CMA
SEC
PER
FAB
Fuse Identification
Anti-tearing
C
A
K
Fuse ID
Address 1
0000 xxxx
$07
$06
$04
$00
A
C
K
Address 2
xxxx xxxx
Atmel AT88SC0104CA/0204CA/0404CA/0808CA [Datasheet]
C
A
K
xxxx xxxx
Command
N
$B4
$B4
A
C
K
Addr 1
d7--- ---d0
$0B
$08
Data
C
A
K
Addr 2
zone
addr
Data x N
d7--- ---d0
N ≤ $08
A
C
K
8664E−CRYPTO−12/11
$00
O
S
T
P
N
Data (N)
N bytes
35