Am I finding correctly that the on board GNSS chip doesn’t have a dedicated small backup battery?
Most GPS/GNSS boards for APM have a internal backup battery to enable HOT starts. On the NAVIO it would also allow the M8N to act as a free RTC for the Pi.
So…? This was thought of and decided that the few cents were not worth it, or I didn’t read the documentation properly?
It’s not about saving a few cents, but a manufacturing decision.
There is no need for battery for GPS to work as an RTC, as soon as it locks on a couple of satellites it will provide the time. Linux version of APM can set the system time according to the GPS.
RTC functionality, from boot, independent of SV visibility would be purely secondary, as a “free” feature.
Like I said, most GPS/GNSS boards for APM (or any NEO-M8N board?) have a internal backup battery to enable HOT starts. That is a at least 30s TTFF advantage.
Please consider that for next revision. It is worth it!
RTC functionality, from boot, independent of SV visibility would be purely secondary, as a “free” feature.
I agree that it would be good, but Navio is intended for use in drones that are used with satellite visibility in 99% cases.
Like I said, most GPS/GNSS boards for APM (or any NEO-M8N board?) have a internal backup battery to enable HOT starts. That is a at least 30s TTFF advantage.
Hot start won’t be that much of a benefit as RPi2 boots 10-15 seconds.
Please consider that for next revision. It is worth it!
Okay, we’ll think about it once again. We initially rejected the battery as it required some additional manufacturing steps that we wanted to avoid in order to save manufacturing time.
I assume one can also use a secondary external GPS unit anyway?
Yes, of course.
