ST - Store data to PDIBUS Data Space using indirect addressingThe ST instruction is used to store data that is serially shifted into the physical layer shift-register to locations within the PDIBUS Data Space. The ST instruction is based on indirect addressing (pointer access), which means that the address must be stored into the Pointer register prior to the data access. Indirect addressing can be combined with pointer increment. In addition to write data to the PDIBUS Data Space, the Pointer register can be written by the ST instruction. Even though the protocol is based on byte-wise communication, the ST instruction supports multiple- bytes address - and data access. Four different address/data sizes are supported; byte, word, 3 bytes, and long (4 bytes). It should be noted that multiple-bytes access is internally broken down to repeated single-byte accesses. The main advantage with the multiple-bytes access is that it gives a way to reduce the protocol overhead.
Write a value to a address with *(ptr++) instruction through the PDI Controller Pseudo Directive: ST *(ptr++) 0xFFPDIBUS hex code: 0x67 0xFF