at90sp0801-01sc ATMEL Corporation, at90sp0801-01sc Datasheet - Page 5

• Manufacturer Part Number: at90sp0801-01sc
• Description: Secure Signature Generation Chip
• Manufacturer: ATMEL Corporation

1495AS–01/02
S
S
S
01010000
01010000
01010000
01000000
00000000
10000000
Data is sent least significant byte first. In some circumstances, there may be no data,
only crc.
Depending on the value of ss, the crc bytes may or may not be included.
The two sequence bits s
transfer to previous and subsequent transfers.
S
go into buffer address 0 and so on. If this bit is set to a 0, then data0 will be stored in the
next location within the buffer after that from the previous transfer. When set, this bit
also resets the CRC generator.
S
must have previously executed a command where s
1, the last two bytes of the information transferred in this block are a CRC value. The
chip will NACK the crc1 byte, if the value sent does not match that computed on the
incoming data. The CRC bytes may not be split across two blocks.
For instance, to write password information (64 bytes) to the chip, the following
sequence of three write commands would be used (assuming 32 byte loads). The
ACKs, NACKs and STOP conditions have been ignored for clarity.
For shorter data transfer values, it is perfectly legal for both s
cates that the entire transfer is taking place in a single block access. As an example of
this, the following command would write a single byte to the buffer:
The chip will NACK writes that attempt to write into the chip beyond the internal buffer,
which may be as short as 320 bytes.
S
0
1
00100000
00100000
00000010
if set to a 1 indicates that this is the first transfer to the buffer and that data0 should
if set to a 1 indicates that this is the last transfer to the buffer. If set to a 0, the chip
01010000
data0
data32
crc0
11000000
1-0
within the command code tell the chip how to relate this
data1
data33
crc1
00000011
data0
data2
data34
0
was set to a 1. When s
crc0
...
...
0
and s
crc1
1
to be set. This indi-
data31
data63
1
is set to a
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