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Low Power Mode
The W24 supports optional low power modes, called Sleep Mode and Deep Sleep Mode, in
which it operates with minimum functionality, and therefore draws significantly less current.
During Sleep Mode the W24 network connection is not lost. W24 continues to monitor the
network constantly for any incoming data.
During low power mode, all of the W24 interface signals are inactive and are kept in their
previous state, prior to activating low power mode. To save power, all the W24 internal clocks
and circuits are shut down, and therefore serial communications are disabled.
In the cases where no Access Point can be found at W24 power-up, W24 will enter Deep Sleep
Mode. During Deep Sleep Mode, network connection does not exist. W24 will periodically come
out of Deep Sleep Mode, to attempt to locate APs. If the search is not successful, the module will
return to Deep Sleep Mode.
Activating Low Power Mode
By default, the W24 powers on in Idle mode. In this mode, all the W24 interfaces and features are
functional and the module is fully active. Sleep mode is activated by setting the AT+iPSE>0.
When the WAKEUP_N signal is disabled (high) and no data is present on the serial interface or
incoming from the Wi-Fi network, and no internal system task is running, W24 will enter Sleep
mode.
When in Sleep mode, the W24 disables all its serial interfaces (USB and UARTs), and the VBUS
output signal of the cellular connector (stacked configuration).
The W24 continues to respond to both external and internal interrupts.
The following conditions must be met for the W24 to enter Sleep mode:
WKUPI_N signal is disabled (high).
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AT+ iPSE and AT+ iS102 parameter values are not 0.
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For example:
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AT+ iWLPS parameter value is not 0, so the Wi-Fi chip is in automatic power save mode.
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No host command in currently being processed.
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No WPA process is currently active. For example, scanning or handshake.
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Carrier lost handling is not in process.
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No data is waiting to be transmitted over any of the active sockets.
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No data is waiting to be sent in SerialNET mode.
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For more information about AT+ iS100 and AT+ iS102 parameters, see the following sections.
Important:
May 31, 2008
AT+ iPSE = 1 activates low power mode after 1 second of inactivity.
AT+ iPSE = 5 activates low power mode after 5 seconds of inactivity.
AT+ iPSE = 0 disables low power mode (default).
W24 will not enter Sleep mode in any case when data is present on the serial
interface or incoming from the Wi-Fi network, or an internal system task is running.
Only when processing of a pending external or internal system task has completed,
W24 will enter Sleep mode according to the AT+iPSE command settings.
Module Hardware Description
Chapter 2: Hardware Interface Description
17
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