User's Manual l TQMa8XxS UM 0101 l © 2022, TQ-Systems GmbH
Page 12
3.2.1.3
Boot modes
After the release of RESET_IN# / IMX_POR# the system controller (SCU) boots from the internal ROM. Depending on the OPT fuses
(eFuse) and the boot mode settings of the system controller the system boots from the selected boot source. The following
interfaces are available as boot source:
•
eMMC
•
QSPI-NOR flash
•
SD card
The SMARC standard requires, depending on the selected boot mode, a defined wiring of the SMARC connector pins
BOOT_SEL[2:0]. These are converted with a CPLD to the boot mode pins BOOT_MODE[3:0].
The FORCE_RECOV# signal is used to switch to the "Force Recovery" mode or the "Serial Downloader", see (1) and (6).
More information about boot interfaces and its configuration is to be taken from the i.MX 8X Data Sheet (1) and the i.MX 8X
Reference Manual (2). Alternatively, an image can be loaded into the internal RAM via serial downloader.
i.MX 8X
SMARC contacts
BOOT_MODE0
BOOT_MODE1
BOOT_SEL0#
BOOT_SEL1#
BOOT_MODE2
BOOT_MODE3
BOOT_SEL2#
CPLD
FORCE_RECOV#
Figure 3:
Block diagram Boot-Mode
The following boot media are provided according to the SMARC standard:
Table 4:
Boot sources
i.MX 8X
BOOT_MODE[3:0]
FORCE_RECOV#
BOOT_SEL[2:0]#
Boot Source
0000
1
101
Remote / Internal eFuses. Defined as Boot from eFuses,
since the i.MX 8X does not define a remote mode.
0001
0
xxx
Recovery-Mode / Serial-Downloader
0010
1
110
eMMC
0011
1
001
SD card
0110
1
100
QSPI NOR flash
Note: Field software updates
When designing a carrier board, it is recommended to have a redundant update concept for field
software updates.
1:
Floating inputs are taken as "1" due to the pull-up on the TQMa8XxS.
