Custom instructions can be sent to the external flash using the CINSTRCONF, CINSTRDAT0, and CINSTRDAT1 registers. It is possible to send an instruction consisting of a one-byte opcode and up to 8 bytes of additional data and to read its response.
A custom instruction is prepared by first writing the data to be sent to CINSTRDAT0 and CINSTRDAT1 before writing the opcode and other configurations to the CINSTRCONF register.
The custom instruction is sent when the CINSTRCONF register is written and it is always sent on a single data line SPI interface.
The READY event will be generated when the custom instruction has been sent.
After a custom instruction has been sent, the CINSTRDAT0 and CINSTRDAT1 will contain the response bytes from the custom instruction.
The data of custom instructions is not part of the stream cipher encryption.