35.3.3.2 STS
- Store Data to Data Space Using Direct
Addressing
The STS
instruction is used to store data that are shifted serially into
the PHY layer shift register to the system bus address space. The STS
instruction is based on direct addressing, and the address must be given as an operand
to the instruction for the data transfer to start. The address is the first set of
operands, and data are the second set. The size of the address and data operands is
given by the size fields presented in Figure 35-9.
The maximum size for both address and data is 32 bits.
The STS
supports repeated memory access when combined with
the REPEAT
instruction.
STS
instruction is depicted in Figure 35-9, following this sequence: - The address is sent.
- An Acknowledge (ACK) is sent back from the UPDI if the transfer was successful.
- The number of bytes, as specified
in the
STS
instruction, is sent. - A new ACK is received after the data have been successfully transferred.