33.7.8.3 Read Memory Transfer

The user can access the data of the serial memory by sending an instruction with DATAEN=1 and TFRTYP=0x1 in the Instruction Frame register (INSTRFRAME).

In this mode the QSPI is able to read data at random address into the serial flash memory, allowing the CPU to execute code directly from it (XIP execute-in-place).

In order to fetch data, the user must first configure the instruction frame by writing the INSTRFRAME. Then data can be read at any address in the QSPI address space mapping. The address of the system bus read accesses match the address of the data inside the serial Flash memory.

When Fetch Mode is enabled, several instruction frames can be sent before writing the bit LASTXFR in the CTRLA. Each time the system bus read accesses become non-sequential (addresses are not consecutive), a new instruction frame is sent with the corresponding address.