Can anyone help me figure out which MAVlink message(s) are used for the GPS toolbar indicator?
I notice that if I unplug the GPS module (or stop the driver) that the GPS values “freeze” instead of showing zeros/blanks/dashes. Seems like they should not keep showing old information and should help provide an indication that GPS information has disappeared by changing to zeros/blanks/dashes.
They come from the GPS_RAW_INT message. My guess is that when you unplug the GPS the GPS_RAW_INT message is no longer sent. Hence they stop updating and keep whatever their last value was. In QGC there no prevention against data which is streamed to the ground suddenly stopping. For any value taken from a streamed mavlink message, it will just stay at the last value it got. Tracking whether QGC suddenly stopped receiving data for all of these different values isn’t going to be a trivial thing to handle.
You should be able to determine whether my guess is what is happening by using the mavlink inspector. When yo upull the gps you should see the rate on the RAW_INT message slowly drop to 0.
okay we will try that. also related is this new software feature request to support dual GPS: