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Software Integration
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FirstGPS Starter Kit User Guide
3.1
Overview
The FirstGPS software library runs as a library to a host application
under a Real-Time Operating System (RTOS). This chapter discusses
a few of the design implementation issues.
3.2
Power-Up and Power-Down
The FirstGPS software is provided as a static library. It must be linked
with the user-defined application task (AppTask) to generate object
code that can be loaded onto a target environment and run. It is the
AppTask’s responsibility to start up and shut down the FirstGPS
engine as required. The two API functions navGpsStart, page 80, and
navGpsShutDown, page 79, are provided for that purpose.
Before any other API calls can be made, the AppTask must call
navGpsStart, page 80, once to power up the GPS engine. In response
to this call, two events are generated:
• NAV_POWER_ON_ACK – The first event is generated
immediately after the call to navGpsStart and indicates that a
request to power up has been received, and that the GPS engine
is starting up.
• NAV_START_UP_COMPLETE – The second event is
generated a few moments later to indicate that the FirstGPS
library and the IO have successfully started and are
running.This may take up to 3 seconds, depending on the
hardware and RTOS.
After the second event has been received, the AppTask may use other
FirstGPS API functions to retrieve library data. In addition, any API
calls that configure library components (such as the receiver or filter
configuration) must also be called at this time, if required.