Boot Sources and Storage Devices

Kria K26 SOM Data Sheet (DS987)

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1.2 English

The K26 SOM includes two nonvolatile storage boot devices, a QSPI flash memory, and an eMMC flash memory. The primary boot device is selected by tying the MODE[3:0] pins to the desired value on your carrier card. The boot-mode pins are made available at the SOM connector to allow flexibility in defining the boot device. The boot-mode configurations for using QSPI or eMMC are shown in the following table. Other boot-mode options can be introduced based on your carrier card design. See the Zynq UltraScale+ Device Technical Reference Manual (UG1085) for the full set of boot-mode definitions. Reference the Kria SOM Carrier Card Design Guide (UG1091) for details on strapping the boot-mode resistors.

Table 1. Boot Mode Pins and Location
Boot Mode PS_Mode Pins[3:0] Physical Pin Location
Quad-SPI (32 bit) 0010 MIO[5:0]
eMMC 0110 MIO[22:13]

The K26 SOM provides two storage devices to enable a primary/secondary boot process with isolation between boot firmware and operating system (OS) storage, or similar device firmware segmentation. As an example of the supported hierarchical boot process, the SOM boot mode can be set to QSPI as the primary boot device, which contains the power-on boot firmware, and then the power-on boot loader (e.g., U-Boot) loads the OS from the eMMC secondary boot device.