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M14A2A User Manual
2.5.2.
Host-to-modem wake-up interface
In applications where the device power consumption is a major target of optimization such as
battery-operated sensors that are based on IOT/M2M modem solution and in addition , include a
third-party host, it is necessary to define a simple interface that will allow both the modem and the host
to be able to enter low power states whenever possible while allowing the other side to wake it up when
required.
For example, if the host has no data to transmit or any other tasks, it may wish to enter some low power
state according to its own capabilities and configurations. If during the time the host is in a low power
state and the modem suddenly receives data, it must wake-up the host.
A similar requirement exists from the other side. If, for example, the modem is in a low power state and
suddenly the host must transmit data, it must to be able to wake-up the modem.
Each side has notification functionality when they are up and ready to follow a wake-up request.
The idea behind the suggested method is to have a very simple interface that will also be pin-limited
(requires only two pins) to fit into such limited-pin-count applications and packages.
The interface consists of two lines: one is driven by the host and received by the modem, and the other
is driven by the modem and received by the host.
Each side can wake the other side by toggling it high and allowing the other side to go to sleep when not
needed by toggling it low.
Toggling the signal high does not necessary mean the other side will enter the low power state ; the
toggling function is only intended to notify the other side that its functions will not be required in the
near term and that it is allowed to enter a low power state if he can (according to its own tasks,
configurations, and capabilities).
The following diagram depicts how this simple interface works. In addition to the two hardware signals,
additional higher-level messages may be defined to pass further information or details between the host
and the modem if required.
If the Powe states of Deep “leep a d
Light Hibe
atio featu e a e e ui ed, it was eco
e ded
to connect WAKEUP_IN and WAKEUP_OUT signal to Host. This design can make sure M14A2A can be
waked up by Host.
