Microchip Technology megaAVR 0 Series Manual page 454

Figure 29-14. REPEAT Instruction Operation
REPEA T
Synch
R E P E A T
(0x55)
Synch S T
(0x55)
( p t r + + )
The figure above gives an example of repeat operation with an ST instruction using pointer post-
increment operation. After the REPEAT instruction is sent with RPT_0 = n, the first ST instruction is
issued with SYNCH and Instruction frame, while the next n ST instructions are executed by only sending
in data bytes according to the ST operand DATA_SIZE, and maintaining the Acknowledge (ACK)
handshake protocol.
If using indirect addressing instructions (LD/ST) it is recommended to always use the pointer post
increment option when combined with REPEAT. Otherwise, the same address will be accessed in all
repeated access operations. For direct addressing instructions (LDS/STS), the address must always be
transmitted as specified in the instruction protocol, before data can be received (LDS) or sent (STS).
29.3.3.8 - Set Activation KEY
KEY
The KEY instruction is used for communicating KEY bytes to the UPDI, opening up for executing
protected features on the device. See
For the KEY instruction, only 64-bit 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 128 bits.
©
2018 Microchip Technology Inc.
OPCODE
1 0 1 0 0 0
REPEAT SIZE
R P T _ 0
DATA_SIZE
D a t a _ 0 D a t a _ n
Table 29-4
Unified Program and Debug Interface (UPDI)
Size B
S i z e B - D a t a s i z e
0 0 B y t e
0 1 R e s e r v e d
1 0 R e s e r v e d
1 1 R e s e r v e d
Rpt nr of Blocks of DATA_SIZE
DATA_SIZE
D a t a B _ 1
A C K
Δd Δd
for an overview of functions that are activated by KEYs.
Datasheet Preliminary
®
megaAVR 0-Series
DATA_SIZE
D a t a B _ n
A C K
Δd Δd Δd
DS40002015A-page 454
R x
T x