Fastrax IT321, Техническое описание

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2007-11-19
Page 13 of 35
IT321_Tech_doc_12
SiRF binary protocol message ID151 ( ref III ). The receiver
stays once in while in Full Power automatically to collect new
ephemeris and almanac data from rising satellites.
2. Push-to-Fix : In this mode the receiver is configured to wake up
periodically, typically every 1800 sec, to collect new ephemeris
data from rising satellites. Rest of the time the receiver stays in
a low power mode. The host wakes up the receiver by ON_OFF
control input interrupt (pulse low-high-low >62us) after which
the receiver performs Hot start and a valid fix is available within
few seconds. This mode is configurable with SiRF binary proto-
col message ID151 (
ref III ).
Note that position accuracy is somewhat degraded in power man-
agement modes when compared to full power operation.
3.3 Hibernate mode
Hibernate mode means a low quiescent power state where only the
internal non-volatile RTC and RAM block is powered on. The main
supply input VDD is kept active all the time, even during Hibernate
mode. The Hibernate mode is entered by host interrupt at ON_OFF
control input (pulse low-high-low >62us).
Other internal blocks like digital baseband and I/O block are internally
powered off, thus output levels are at low state and any inputs, ex-
cluding ON_OFF input, like UART RXA should be disconnected or
forced to low state.
The receiver wakes up from Hibernate mode and returns to Normal
mode after next ON_OFF interrupt (pulse low-high-low >62us) allow-
ing fast TTFF with either Hot or Warm start.
3.4 Programming mode
Programming mode is only available with the flash version (GSC3LTf)
with the embedded 4Mbit flash memory. The ROM code version does
not support programming.
Programming via HW-booting mode is utilized by forcing the BOOT1
and BOOT2 control inputs for high state (Flash programming, follow-
ing table) during power up. Now the GPS module boots for the UART
and waits for the boot loader commands from the host (an application
running on the host, SiRFFlash). It is suggested that all applications
using embedded flash version should support the HW-booting by ac-