37.3.3 UPDI Instruction Set

The communication through the UPDI is based on a small instruction set. These instructions are part of the UPDI Data Link (DL) layer. The instructions are used to access the UPDI registers since they are mapped into an internal memory space called “ASI Control and Status (CS) space”, as well as the memory-mapped system space. All instructions are byte instructions and must be preceded by a SYNCH character to determine the baud rate for the communication. See the UPDI UART section for information about setting the baud rate for the transmission. Figure 37-7 gives an overview of the UPDI instruction set.