I had similar problems, it very nearly drove me insane but, with the help of some of the group I am now programming the UDB like there was never a problem. Stick at it, dont give in, you will win in the end
this issue might be related to following reasons.( it was discussed else were too .. I could not find the location )
1. MPLab installation is not in default location ie. c:\program files\... and is in c:\... or another drive ie. d:\ .
The Matrixpilot code is/was compiled /assumes the above, some files in it needs to reflect the path of MPLab tools location.
I agree with Peter, it would be a good idea to see if the UDB is receiving messages from the GPS. The is a possibility that there is an open solder joint between the GPS connector and the board. The way Peter has suggested is a good way to find out.
Just to summarize a couple of points that we have already covered:
1. The dim LED on the GPS is normal. That is a 100% positive indication that messages are traveling from the UDB to the GPS. When the GPS is fresh from the factory, it is running in NMEA mode. In that mode, the LED on the GPS is in indicator, and it will be bright. However, the first time the GPS is powered up connected to the UDB, the UDB sends is messages that commands it into binary mode. That will turn off the red LED on the GPS, so that is normal.
2. A few months ago we changed the design of the UDB to use a lower power supply voltage, 4.5 volts instead of 5 volts, so the GPS is operating at 4.5 volts. We tested it, and that is ok. You reported 4.3 volts, and that is a little be low, but I do not think it would cause any trouble.
Today i have decided to start all over again.
Installed the MPLAD 8.5 on its default location
Installed the compilers on its default location
Extracted the project again and everithing copiled first try(that is a good sign)
With my old 7.3 D: drive instalation i wanted to try the selft test procedure.
There was a strange msg that the format had changed (or something like that)
After fresh installtion of the MPLAB and compiler the selft test compiles first time no problem .
With the self test firmare the STAT2 led blinks - this means that the GPS works ok and RED led on the GPS is on (not dimmed)
It is midnight here so i can't go out and check GPS lock - will do it first thing in the morning .
So to summarize your build failed issue/error, the issue was resolved by reinstalling MPlab in default location, Yes?
The alternate method is to change the path in some file(?) in matrix pilot.this was successfully done by some one else too. Cheers