35.1 Overview

The Quad SPI Interface (QSPI) circuit is a synchronous serial data link that provides communication with external devices in Host mode.

The QSPI can be used in SPI mode to interface serial peripherals, such as ADCs, DACs, LCD controllers and sensors or in Serial Memory mode to interface serial Flash memories.

The QSPI allows the system to execute code directly from a serial Flash memory (XIP) without code shadowing to SRAM. The serial Flash memory mapping is visible in the system as other memories (ROM, SRAM, embedded Flash memories and so on). XIP mode is not available for a secured or code protected device for security reasons. This is achieved by blocking off AHB accesses (only instruction) on the CPU side from QSPI. QSPI returns an error on the transactions where the CPU is requesting instructions from QSPI-connected external memories.

With the support of the Quad-SPI protocol, the QSPI allows the system to use high-performance serial Flash memories that are small and inexpensive in place of larger and more expensive parallel Flash memories.