I am using a BG95-M3 module and I have got that thing running pretty well.
For my application I need to have a real-time clock calibrated with something running from a crystal, the modem is perfect for this.
I tried using the AT+CCLK? output but could only query the clock 58 times a second, that’s around 20mS accuracy, almost half an hour a day. I was hoping for something better.
I have made something using the NET_STATUS, where I can get some 1800ms/200ms pulses out. That’s actually ok, but I am wondering how accurate they are in terms of timing?
As an alternative I was wondering if I could configure the MAIN_RI to do actual 1 seconds pulses, looks like it is possible, but again, how accurate is it?
Anyway of assigning a precise clock signal to one of the GPIOs?
1.AT+cclk is modem time ，it sync from NITZ time ， normally it is very precise .
2.as your side , it have 20ms offset, i think it come from UART hardware .
3. It is not a good choice to obtain clock source from GPIO, because hardware delay is difficult to control
so up to now ， normally we recommend the customer use AT+QLTS or AT+CCLK? still .
AT+QLTS is get network current now , pls try it .
I may not have made clear enough what I am trying to do.
Yes, I do update the time RTC on my device using AT+CCLK, that works just fine. But the accuracy of my own clock is the issue.
My device is running off an RC generated clock signal, that can run plus/minus 3%. So I am using a precise pulse or known timing to calibrate this clock signal.
When using AT+CCLK I need to find the moment when it changes from one second to another, but as I can only make the request 58 times a second. That also assumed that every request is executed at the same speed.
On the previous version of our hardware with another vendor, I was able to pull a very accurate 1 second clock signal from the standalone GPS module.
So back to the question: How precise are the MAIN_RI and NET_STATUS? If generated by the hardware and since you’re most likely using a crystal, they could be very accurate. I just don’t see anything in the spec.