I’ve noticed that after the ADL_SIM_EVENT_INSERTED the RTC goes awry.
For example, let’s say I set the time to “19/08/2013 09:23:16”. This is all fine, but if I then insert a SIM card the RTC value changes to “18/08/2013 23:53:20”. No other events or actions seem to cause this, just ADL_SIM_EVENT_INSERTED. This is highly repeatable.
Is the time change ‘random’ each time you do a sim insert? Or is the time actually being changed to UTC from your local time?
Some networks transmit NITZ (Network Information and Time Zone) packets. There’s no specific time that the network transmits these packets, but I’ve noticed that you will get one when you make a successful network registration, and sometimes when you change cells.
If you set the appropriate bit in the AT+WIND command, you will get unsolicited +WIND:15 responses when you get a NITZ message.
I recall that there is a command somewhere that will automatically sync the module time to the network - but I can’t find any doco on it at the moment. Do have a look at AT+CTZU though as a starting point.
Cool. Not all telcos provide the NITZ message - and there is a lot of variation between which NITZ sub messages are provided as well. Note that the time zone (+38 in your case) is the number 15 minute increments difference between the time provided and UTC. In your case you are 9.5 hours (central Australia?) ahead of UTC.
Me too. I’ll keep wracking my brain trying to remember where/how I saw the module automatically update time based on the network connection.
I don’t use the RTC backup battery - I forget exactly what it was, but having it connected caused my module to misbehave. The application periodically synchronises the RTC to an external device anyway, so it’s not needed.
When it says the “RTC is reset”, I read that as setting it back to the default value. The problem doesn’t seem to be power-up, it instead seems to happen after ADL_SIM_EVENT_INSERTED. If the modem’s been running for a while I can unplug / replug the SIM and see it change the RTC on me. I enabled all WIND notifications but I couldn’t see anything that would explain why it does this.
You’re right that I’m UTC+9:30, which makes it quite annoying when it takes it upon itself to set the RTC to UTC+0:00!