31.3.3.8 KEY - Set Activation Key or
Send System Information Block
The KEY instruction is used for communicating key bytes to the UPDI or for
providing the programmer with a System Information Block (SIB), opening up for executing
protected features on the device. See Key Activation Overview for an overview of
functions that are activated by keys. For the KEY instruction, only a
64-bit key size is supported. The maximum supported size for SIB is 128 bits.
KEY Instruction
Operation
Figure 31-16 shows the transmission of a key and the reception of a SIB. In both
cases, the Size C (SIZE_C) field in the operand determines the number
of frames being sent or received. There is no response after sending a
KEY to the UPDI. When requesting the SIB, data will be transmitted
from the UPDI according to the current guard time setting.