33.3.3.8 KEY
- Set Activation
KEY
The KEY
instruction is used for communicating KEY bytes to the UPDI,
opening up for executing protected features on the device. See Table 33-5for an overview over functions that are activated by
KEYs. For the KEY
instruction, only 64bit KEY size is supported. If the
System Information Block (SIB) field of the KEY
instruction is set, the
KEY
instruction returns the SIB instead of expecting incoming KEY
bytes. Maximum supported size for SIB is 128bits.
KEY
Instruction
OperationThe Figure above shows the transmission of a KEY, and the reception of a
SIB. In both cases, the SIZE_C
field in the opcode determines the
number of frames to be 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.