Hello. I have a L96 gnss module. What happend if I send to module hot or warm start PMTK-command when the module has been backuped for more than 3, 5, 10, 24 or more hours? Does the module wakeup? What type of start it will be (hot, warm , cold or other)?
Hi lldar Belkin,
The difference between hot start, warm start and cold start.
- hot start: time, position and ephemeris data are available. A module turn off the main power( VCC ) but hold backup power( V_BCKP ), and its position doesn’t move obviously, turn off VCC for a short period of time( generally within 2 hours). When it startup again, it is hot start.
- cold start: neither time, position and ephemeris data are unavailable. A module turn off all power supply, or clear up flash memory. When it startup again, it is hot start.
- warm start: time and position are blurry, and ephemeris data is unavailable. A module turn off the main power( VCC ) but hold backup power( V_BCKP ) for a period of long time. V_BCKP supplies power for RTC.
The commands for the three ways of start aim to simulate the three situations which were mentioned above, in order to facilitate your testing. You can also use cold start command to clear up ephemeris data or some configurations.
There is no need to send some start commands in daily use. If you want to wake up the module from backup mode, please refer to Hardware Design.
Thank you for answer!
I knew that information. My question is not about it.
I need to know what happend if I send hot start or warm start PMTK-command when GNSS has no any data about almanac and ephemeris.
Hi Ildar Belkin,
The results of startup mainly relate to time, position and ephemeris data.
For this situation, no matter what startup command you send to the module, it will perform a warm/cold start ( depending on time and position are available or not ). It you want to improve TTFF( time to first fix ), you can implement AGNSS function. The almanac and ephemeris data will be automatically saved after the module output a valid position. But these data are less comprehensive than AGNSS EPO data.
Hi Raphael-Q! Thank you!