COMe-bTL6 - User Guide. Rev. 1.5
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3.10.
Real Time Clock (RTC)
The RTC keeps track of the current time accurately. The RTC’s low power consumption enables the RTC to continue
operation and keep time using a lower secondary source of power while the primary source of power is switched off
or unavailable.
The COMe-bTL6 supports typical RTC values of 3 V and less than 10 μA. When powered by the mains power supply
on-module regulators generate the RTC voltage, to reduce RTC current draw. The RTC’s battery voltage range is 2.8 V
to 3.47 V.
It is not recommended to run a system without a RTC battery on the carrier board. Even if the
RTC battery is not required to keep the actual time and date when main power is off, a
missing RTC battery will cause other side effects such as longer boot times. Intel processor
environments are generally designed to rely on RTC battery voltage
3.11.
Serial Peripheral Interface (SPI)
The Serial Peripheral Interface (SPI) bus is a synchronous serial data link where devices communicate in master/slave
mode and the master device initiates the data frame. Multiple slave devices are allowed with individual slave select
(chip select) lines.
The SPI interface may only be used with a SPI Flash device to boot from the external BIOS on
the carrier board.
There is an option for a General Purpose SPI (GSPI) connection to COMe instead of the SPI interface for external Boot.
GSPI. This requires a hardware modification in the form of additional resistors.
Table 31: GSPI/SPI Hardware Options
GSPI/SPI Hardware Options
COMe SPI Bus
Base module variant
Standard boot SPI bus
GSPI_HARDWIRED
[1]
GSPI bus
GSPI_MUXED
[1]
SPI/GSPI selectable by BIOS setting
Advanced> Miscellaneous> SPI lines active
[1]
Implemented on request only.
General purpose SPI connects to COMe instead of boot SPI and requires a hardware
modification in the form of additional resistors. Implemented on request only
The COMe-bTL6 supports on-module and carrier board boot from SPI Flash. The SPI flash chip source is configured
using the pins A34 (BIOS_DIS0#) and B88 (BIOS_DIS1#).