ATSGA204A View Datasheet(PDF) - Microchip Technology
Part Name
Description
MFG CO.
'ATSGA204A' PDF : 93 Pages View PDF
ATSHA204A
Security Commands
Bits Meaning
2 The value of this bit must match the value in TempKey.SourceFlag or the command returns an error.
1 – 0 Must be 0b00.
8.5.10
Lock Command
Write either LockConfig or LockValue to 0x00, to change the permissions in the designated zone.
This command fails if the designated zone is already locked.
Prior to locking the device, the ATSHA204A uses the CRC-16 algorithm to generate a summary digest of
the designated zone(s). The calculation is made identically to the CRC computed over the input and
output blocks.
• Configuration Zone: The CRC is calculated over all 88 bytes.
• Data and OTP Zone: Their contents are concatenated in that order to create the input to the CRC
algorithm.
If the input summary does not match that computed on the device, an error is returned and the
personalization process should be repeated.
Table 8-20. Input Parameters
Name Size Notes
Opcode Lock
1 0x17.
Param1 Zone
0 = CRC is checked when the zone is locked.
Bit 7: 1 = CRC check is ignored and the zone is locked, regardless of the state of
the memory. Microchip does not recommend using this mode.
1 Bits 6-1: All bits must be zero.
Bit 0:
0 = Configuration zone
1= Data and OTP zone
Param2 Summary 2 Summary Digest of the designated zones, or should be 0x0000 if Zone<7> is set.
Data —
0—
Table 8-21. Output Parameter
Name
Size Notes
Success
1 Upon successful execution, the ATSHA204A returns a value of zero.
8.5.11
MAC Command
The MAC command computes a SHA-256 digest of a key stored in the device, a challenge and other
information on the device. The output of this command is the digest of this message. If the message
includes the serial number of the device, the response is said to be “diversified”.
The normal command flow to use this command is as follows:
1. Run the Nonce command to load input challenge and optionally combine it with a generated
random number. The result of this operation is a nonce stored internally on the device within
tempkey.
© 2018 Microchip Technology Inc.
DS40002025A-page 55
Share Link: 
