Smb; Features; Acpi Power States - Kontron COMh-caRP User Manual

Due to the fact that both the pull-up and pull-down termination resistors are weak, it is possible to
override the termination resistors using external pull-ups, pull-downs or IOs. Overriding the
termination resistors means that the GPIO pins can be considered as bi-directional since there are no
restrictions whether you use the available GPIO pins in the in-direction or out-direction.

3.4.13 SMB

The System Management Bus (SMB) is a simple 2-wire bus for low-speed system management
communication. The PCH or the SOC controls the SMB. The module's SMB connects typically to the
memory and the hardware controller.

3.5 Features

3.5.1 ACPI Power States

ACPI enables the system to power down, save power when not required (suspend) and wake up when
required (resume).
ACPI controls the power states S0-S5, where S0 has the highest priority and S5 the lowest priority.
S0 Working state
S1 Sleep (typically not supported anymore)
S2 Deep Sleep (typically not supported anymore)
S3 Suspend-to-RAM
S4 Suspend-to-disk / Hibernate
S5 Soft-off state
Table 25: ACPI Power States Function
Not all ACPI defined power states are available.
The COMh-caRP supports ACPI 6.0 and the power states only.
Systems that support the low-power idle state do not use power states S3 and S4.
To power on from states S3, S4 and S5 use
Power Button
WakeOnLAN (S3, S4)
The OS must support wake up from an USB device and the carrier board must power the
USB port with the standby voltage.
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