SPRAD95 june 2023 AM2732 , AM2732-Q1
There are a few things to consider when choosing a flash part for application purposes. This document covers some of the basic requirements that a specific flash memory must support to be compatible with the AM273x device during both boot operation and application execution.
The QSPI flash memory can be utilized two different ways in the user system:
When picking a flash memory IC, the device must comply with all boot requirements of the SoC. If the memory is used as boot media, some guidelines must be followed to work efficiently as a storage device during application.
Figure 1 depicts the flash memory organization once the secondary bootloader (SBL) image and valid application image are present.
Figure 2 shows the Boot Flow process where the flash usage is put into perspective, assuming a valid image is already present in flash.
As Figure 2 illustrates, the boot flow process is a sequence adopted by AM273x that starts upon power-on. ROM code is already set to work in a certain way and expects specific instructions from the flash and also expects specific timing and framing configurations for establishing communication. For the AM273x device, ROM code expects the following support:
All of this information is available in the data sheet of the flash device being evaluated. A flash device must support all of the points mentioned above to meet AM273x compatibility requirements.
Application-specific requirements tend to be more lenient then the ROM code execution requirements because improper configuration and lack of support do not result in system boot failure. The following requirements must be met for general flash applications:
The following list includes a few things to consider when deciding on what flash part to use for the application:
The MCU PLUS SDK comes with default flash software support for specific flash memories in the library. If the evaluated flash meets requirements but does not have compatible software drivers in the SDK, use the following link for instructions on how to add support for the flash memory.
The following list shows devices that meet the requirements for correct operation with the Sitara MCU AM273x devices as per the information contained in their data sheets. This list is be used for reference only:
MCU – Microcontroller Unit
QSPI – Quad Serial Peripheral Interface
SoC – System on a Chip
UART – Universal Asynchronous Receiver-Transmitter
SBL - Secondary Boot loader
ROM – Read-only memory
SFI – Serial Flash Interface
SDK – Software Development Package