Advanced LAN Bypass, Руководство пользователя

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Advanced LAN Bypass User Manual 10
The WDT is also strobed (to keep it from timing out) via the messaging interface
(inband).
2.5.2 Toggle Pin Mechanism
In this mode, a dedicated signal ("toggle pin") between the NIC and LAN Bypass
MCU is used to strobe the WDT and keep it from timing out. Every signal state
change (i.e., each rising or falling edge) will be treated as a WDT strobe.
This mechanism is disabled by default to provide backward compatibility with the
Legacy LAN Bypass implementation. To enable the toggle pin mechanism, two acti-
vation methods are supported:

It can be activated "on demand" by issuing the respective command via the reg-
ular messaging interface between the host and LAN Bypass MCU

It can be permanently enabled by configuration and a specific start sequence on
the toggle pin will start the timer
In toggle pin mode, no communication over the regular messaging interface is
required. The host SW simply keeps toggling the dedicated signal in order to strobe
the WDT.
Arming and auto re-arming functionalities further simplify the use of the toggle pin
mode.
2.5.2.1 On Demand Mode
Once toggle pin mode is enabled and set to on demand (manual) mode, the WDT is
armed.
Once armed, the host SW needs to execute a specific start sequence on the toggle
pin (initiated through the "lbp_start_wdt_by_toggle" API call) to start the WDT.
In normal operation, the WDT will be disarmed when it expires and needs to be re-
armed by the host SW.
For use cases where manual re-arming is not desired, auto re-arming can be
enabled. When this is enabled, the WDT will be automatically re-armed when it
expires. A subsequent change of the toggle signal will restart the WDT.
The auto re-arm function can be configured as a non-volatile setting of the LAN
Bypass MCU.
2.5.2.2 Permanent Mode
Toggle pin mode can be permanently enabled as a non-volatile configuration setting
for the LAN Bypass MCU. In this mode, toggle pin mode will automatically be
enabled and the WDT will be armed by default.
In addition, the auto re-arming features can be used as in on demand mode.
In combination, the non-volatile configuration setting for the WDT count, toggle pin
permanent enable, and auto re-arm allow for a one-time configuration of the WDT via
the host messaging interface. Once configured, no inband messaging is required
anymore but all WDT operations can be accomplished out-of-band via the toggle pin.
Toggle pin mode summary:

Enable/disable (volatile setting)
Toggle pin mode manual enable/disable (on demand mode)

Arm/disarm (volatile setting)
Arm/dis-arm the WDT (if armed, a change in toggle signal will implicitly start the
WDT)

Auto re-arm (non-volatile setting)
When the WDT expires, it will be re-armed by a subsequent change of the tog-
gle signal