SAM-M10Q - Integration manual
•
Cold start:
In cold start mode, the receiver has no information from the last position (e.g.
time, velocity, frequency etc.) at startup. Therefore, the receiver must search the full time and
frequency space, and all possible satellite numbers. If a satellite signal is found, it is tracked
to decode the ephemeris (18-36 seconds under strong signal conditions), while the other
channels continue to search satellites. Once there is a sufficient number of satellites with
valid ephemeris, the receiver can calculate position and velocity data. Other GNSS receiver
manufacturers call this startup mode Factory startup.
•
Warm start:
In warm start mode, the receiver has approximate information for time, position,
and coarse satellite position data (Almanac). In this mode, the receiver after power-up
normally needs to download ephemeris before it can calculate position and velocity data.
As the ephemeris data usually is outdated after 4 hours, the receiver will typically start with
a warm start if it has been powered down for more than 4 hours. In this scenario, several
augmentations are possible. See
•
Hot start:
In hot start mode, the receiver was powered down only for a short time (4 hours
or less), so that its ephemeris is still valid. Since the receiver does not need to download
ephemeris again, this is the fastest startup method.
Using the UBX-CFG-RST message, you can force the receiver to reset and clear data, in order to see
the effects of maintaining/losing such data between restarts. For this purpose, use the
navBbrMask
field in the UBX-CFG-RST message to initiate hot, warm, and cold starts, or a combination of startup
modes.
The reset type can also be specified. This is not related to GNSS, but to the way the software restarts
the system.
•
Hardware reset
uses the on-chip watchdog to electrically reset the chip. This is an immediate
asynchronous reset. No stop events are generated.
•
Controlled software reset
terminates all running processes in an orderly manner. Once the
system is idle, restarts the receiver operation, reloads its configuration and starts to acquire
and track GNSS satellites.
•
Controlled software reset (GNSS only)
only restarts the GNSS tasks, without reinitializing the
full system or reloading any stored configuration.
•
Hardware reset (after shutdown)
uses the on-chip watchdog to reset the receiver after
shutdown.
•
Controlled GNSS stop
stops all GNSS tasks. The receiver will not be restarted, but will stop any
GNSS-related processing.
•
Controlled GNSS start
starts all GNSS tasks.
below contains an overview of the different reset types and the data that is cleared.
Reset type
Clears RAM
Clears BBR
0x00 - Hardware reset (immediately),
0x04 - Hardware reset (after shutdown)
Yes
Yes
0x01 - Controlled Software reset
Yes
No
0x02 - Controlled Software reset (GNSS only),
0x08 - Controlled GNSS stop,
0x09 - Controlled GNSS start
No
No
RESET_N pin
Yes
Yes
Table 11: Overview of the available reset types
UBX-22020019 - R01
2 Receiver functionality
Page 24 of 72
C1-Public
