Boot Device Selection - Embedian SMARC T335x User Manual

Embedian, Inc.

4.3 Boot Device Selection

SMARC hardware specification defines three pins (BOOT_SEL[0:2]) that allow
the Carrier board user to select from eight possible boot devices. Sitara
AM335x bases on SYSBOOT configuration to determine the boot devices.
The boot select utilizes SYSBOOT and line decoder/de-multiplexer logic to
meet the SMARC specification. The BOOT_SELx# pins are weakly pulled up
on the Module and the pin states decoded by module logic. The Carrier shall
either leave the Module pin Not Connected ("Float" in the table below) or shall
pull the pin to GND, per the table below.
Carrier Connection
BOOT_SEL2# BOOT_SEL1#
0 GND
1 Float
2 GND
SMARC T335x Computer on Module User's Manual v.1.2
BOOT_SEL0#
GND Float
Float GND
Float Float
Boot Source
Carrier SD Card
Module eMMC Flash
Carrier SPI
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