ATSHA204 ATMEL [ATMEL Corporation], ATSHA204 Datasheet - Page 33

• Manufacturer Part Number: ATSHA204
• Description: Atmel CryptoAuthentication
• Manufacturer: ATMEL [ATMEL Corporation]

8.1.2
Status/Error Codes
The device does not have a dedicated status register, and so the output FIFO is shared among status, error, and command
results. All output from the device is returned to the system as complete blocks, which are formatted identically to input blocks:
After the device receives the first byte of an input command block, the system cannot read anything from the device until the
system has sent all the bytes to the device.
After wake and after execution of a command, there will be error, status, or result bytes in the device’s output register that can
be retrieved by the system. When the length of that block is four bytes, the codes returned are detailed below in Table 8-3.
Some commands return more than four bytes when they execute successfully: the resulting packet description is listed in the
command section below.
CRC errors are always returned before any other type of error. They indicate that some sort of I/O error occurred and that the
command may be resent to the device. If a command includes both parse and execution errors, there is no particular
precedence enforced – an execution error may occur before a parse error and/or the reverse.
Table 8-3.
State Description
Successful
Command Execution
Checkmac
Miscompare
Parse Error
Execution Error
After Wake, but prior
to first command
CRC or other
Communications
Error
•
•
•
Count
Packet
2-byte CRC
Status/error Codes in 4-byte Blocks
Error/Status
0x00
0x01
0x03
0x0F
0x11
0xFF
Description
Command executed successfully.
The CheckMac command was properly sent to the device, but the input client
response did not match the expected value.
Command was properly received, but the length, command opcode, or parameters
are illegal, regardless of the state (volatile and/or EEPROM configuration) of the
ATSHA204.
Changes in the value of the command bits must be made before it is re-attempted.
Command was properly received, but could not be executed by the device in its
current state.
Changes in the device state or the value of the command bits must be made
before it is re-attempted.
Indication that the ATSHA204 has received a proper wake token.
Command was not properly received by the ATSHA204, and should be
re-transmitted by the I/O driver in the system.
No attempt was made to parse or execute the command.
Atmel ATSHA204 [DATASHEET]
8740D−CRYPTO−3/12
33