34.3.3.8 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 Table 34-4 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
The figure above 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.