TW5340 User Manual
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©2014 -2015 Tallysman Wireless, Inc.
Confidential
7.2
Standby Mode
Standby mode stops the navigation operation and all supply inputs are powered down
and power drain is reduced to approx. 200 uA. Standby mode can be configured to
periodically enter and exit standby mode for specified times see section 9.8
The general purpose output pin provides a positive feedback that the device has
entered Standby mode. When Not In standby the output is pulled high, when in standby
the output is floating.
External control
The W5340 can enter Standby mode by issuing a “$PSTMGOTOSTANDBY” command.
$PSTMGOTOSTANDBY,1,<sleep time>,0,<sleep time>
<Sleep time> is the number of seconds to remain in standby mode. Note the two sleep
times in the command must be identical.
The TW5340 can be woken from standby state by the wakeup pin, otherwise it will wake
after the specified “sleep time”
Pin 3 on the TW5340 can be used to wake the device up. To exit Standby mode the
Wake-Up pin must be pulsed low for approximately 1 ms by an open collector output.
Note: If the TW5340 is in Standby mode for greater 30 minutes the ephemeris data may
old and have to be re-acquired before a GNSS position can be resolved resulting in a
cold start of approximately 50 to 90 seconds.
As a rule of thumb the TW5340 should be on for 30 seconds every 30 minutes to
guarantee a hot start of less than 10seconds.
Note: For applications that need to conserve power by waking up quickly from standby
mode and getting a fix as quickly as possible it is recommended that both GPS &
GLONASS constellations are enabled
Initialize GPS time
Acquisition of a position fix can be sped up by initializing the TW5430 with the GPS time.
The following NMEA command can be used
$PSTMINITTIME
$PSTMINITTIME,<Day>,<Month>,<Year>,<Hour>,<Minute>,<Second><cr><lf>
