ATSGA204A View Datasheet(PDF) - Microchip Technology
Part Name
Description
MFG CO.
'ATSGA204A' PDF : 93 Pages View PDF
ATSHA204A
Security Commands
The Pause command differs from the idle flag/sequence in that individual devices on the single pin bus
may be selected to go into the idle state, as opposed to the idle flag which causes all the
CryptoAuthentication devices on the bus into the idle state.
If the EEPROM Selector byte does not match the input selector parameter, the device immediately goes
to the idle state. If the input selector parameter does match the configuration selector byte, the device
returns a success code of 0x00.
The Pause command cannot be used to put the devices into the sleep state.
Table 8-28. Input Parameters
Name
Size Notes
Opcode
Pause
1 0x01.
Param1
Selector
1 All devices that do not match this value go to idle state.
Param2
Data
Zero
—
2 Must be 0x0000.
0—
Table 8-29. Output Parameter
Name Size Notes
If the command indicates that some other device should idle, the ATSHA204A returns a value of
Success 1 0x00.
If this device goes to idle, no value is returned.
8.5.14
Random Command
The Random command generates a random number for use by the system.
Random numbers are generated through a combination of the output of a hardware RNG and an internal
seed value stored in the EEPROM or SRAM. The external system may choose to update the internally
stored EEPROM seed value prior to the generation of the random number as part of the execution of the
Nonce or Random command, for highest security, Microchip recommends that the EEPROM seed
always be updated.
The Random command does not provide a mechanism to integrate an input number with the internal
stored seed. If this functionality is desired, the system should use the Nonce command and ignore the
generated nonce.
Prior to the configuration section being locked, the RNG produces a 32 byte value of 0xFF, 0xFF,
0x00, 0x00, 0xFF, 0xFF, 0x00, 0x00... to facilitate testing.
The same internally stored seeds are used for both the Nonce and Random commands. Use of
Mode<0> ensures that the EEPROM is updated, if necessary.
Table 8-30. Input Parameters
Name
Size Notes
Opcode Random
1 0x1B.
Param1 Mode
1 Controls the mechanism of the internal RNG and seed update.
© 2018 Microchip Technology Inc.
DS40002025A-page 59
Share Link: 
