Kontron SMARC-sAL28, User Manual

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SMARC-sAL28 User Guide. Rev. 1.0
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6/ Configuration
6.1. Boot Mode
The following table shows the possible boot sources on the carrier board defined in SMARC 2.0 spec:
Table 24: Boot Options on the carrier board
Carrier Connection Boot Source Supported on
sAL28
BOOT_SEL2# BOOT_SEL1# BOOT_SEL0#
0 GND GND GND Carrier SATA No
1 GND GND Float Carrier SD Card From U-Boot
2 GND Float GND Carrier eSPI
(CS0#) From U-Boot
3 GND Float Float Carrier SPI
(CS0#) From U-Boot
4 Float GND GND Module device
(NAND, NOR) No
5 Float GND Float Remote boot
(GBE, serial) From U-Boot
6 Float Float GND Module eMMC
Flash From u-boot
7 Float Float Float Module SPI From u-boot
When the CPLD code is active, the SL1028A boot selection pins are pulled from CPLD to boot from I2C_LOCAL bus
(LS1028A I2C1). The EEPROM at I2C_LOCAL bus (address 0x50) contains RCW and PBI which selects the XSPI1_A bus
with chip select 0 to boot from the connected SPI NOR flash.
If the CPLD is not active or if the boot process did not work from I2C1 the SL1028A boot selection pins can be pulled
to XSPI1_A bus which is the default failsafe mechanism in CPLD.
Boot from external SPI is possible with resistor option: disconnect SL1028A chip select 0 from SPI flash and connect
SL1028A chip select 0 with SMARC connector ESPI_CS0.
6.2. Configurable Watchdog
There are two watchdogs: a CPU internal and CPLD support watchdog.
6.3. RTC current consumption
The VDD_RTC pin at the SMARC 2.0 Connector has the ability to charge a gold cap capacitor on the carrier. The
power source of the VDD_RTC voltage is V_3V3_S5 with BAS70 as series protection diode and an additional series
resistance of 240 Ohm.
Optionally, the series resistance is replaceable with an additional BAS70 diode to protect a battery circuit on a
carrier which has no diode protection (disable gold cap charging capability).
Table 25: Maximum current consumption of RTC
Ambient
temperature Maximum Current in
VDD_RTC
-20°C 0.4
µ
A
25°C 0.6
µ
A
85°C 1.8
µ
A