TCO Modes

Intel® 800 Series Chipset Family Platform Controller Hub (PCH)

Datasheet, Volume 1 of 2

ID	Date	Version	Classification
833778	01/07/2025		Public

TCO Compatible Mode

In TCO Legacy/Compatible mode, only the host SMBus is used. The TCO target is connected to the host SMBus internally by default. In this mode, the Intel^® Management Engine (Intel^® CSME) SMBus controllers are not used and should be disabled by soft strap.

TCO Compatible Mode SMBus Configuration

In TCO Legacy/Compatible mode the PCH can function directly with an external LAN controller or equivalent external LAN controller to report messages to a network management console. The table below includes a list of events that will report messages to the network management console.

Event Transitions that Cause Messages

Event	Assertion?	Deassertion?	Comments
INTRUDER# pin	Yes	No	System must hung in S0 state
Watchdog Timer Expired	Yes	NA	System will enter to hung state
SMBALERT# pin	Yes	Yes	System must hung in S0 state
BATLOW#	Yes	Yes	System must hung in S0 state
SYSPWR_FLR	Yes	No	System will enter to hung state

Advanced TCO Mode

The PCH supports the Advanced TCO mode in which SMLink0 and SMLink1 are used in addition to the host SMBus.

In this mode, the Intel^® CSME SMBus controllers must be enabled by soft strap in the flash descriptor. Refer to figure below for more details.

In advanced TCO mode, the TCO target can either be connected to the host SMBus or the SMLink0.

SMLink0 is targeted for integrated LAN. When an Intel LAN PHY is connected to SMLink0, a soft strap must be set to indicate that the PHY is connected to SMLink0. When the Fast Mode is enabled using a soft strap, the interface will be running at the frequency of up to 1 MHz depending on different factors such as board routing or bus loading.

SMLink1 can be connected to an Embedded Controller (EC) or Baseboard Management Controller (BMC) use. In the case where a BMC is connected to SMLink1, the BMC communicates with the Intel Management Engine through the Intel^® CSME SMBus connected to SMLink1. The host and TCO target communicate with BMC through SMBus.