The COM port, COM3, had just disappeared from my laptop. Nothing I did could bring it back. I got an automatic Windows Update minutes before I plugged it in and it did not work. This was suspicious. I did a bunch of things to the PC to try to make it work:
- I rebooted the PC multiple times
- Updated to the latest Mission Planner
- Reinstalled Mission Planner from scratch
- Reinstalled the Virtual COM Port driver
- Hard removed COM3 and reinstalled the Virtual COM Port driver
- Hard reinstalled FTDI drivers by themselves
- I thought that maybe I had connected it to a low-power USB port and there just wasn't quite enough juice to get it working. I tried all the USB ports on the laptop to no avail.
After some thought, I realized that the power rails in a USB connector are longer than the signal rails. It makes sense that they are physically engaged before the signal rails are.
Silly me. In all my debugging, I had never reseated the Flight Controller end of the USB cable. I had done it all at the laptop end many times. One quick reseat and it was working fine. I did four things differently the time it worked. I'm listing them all, but I'm pretty sure it was that the USB connector wasn't all the way plugged in to the Flight Controller.
Differences:
- Waited 20 minutes without anything plugged in (heat? built-up charge? gremlins?)
- Reseated the USB cable at the Flight Controller end
- I connected to the laptop via USB after connecting to the Flight Controller..... it really shouldn't matter.
- Held down the Flight Controller reset button while I plugged USB to the laptop, but I don't think that had anything to do with it.
I just wanted to mention it in case I'm wrong. One of those four things (or some odd combination plus reinstalling all the software above) did it. I'm reasonably confident it was reseating the USB cable at the Flight Controller.
So the long and short of it is that the Flight Controller fix made the GPS module work. This is good progress.
One thing that puzzles me is how good a GPS signal I get indoors. This is a cheap GPS module, but I'm seeing 7 satellites indoors. Can that be possible? The GPS units I use at work are orders of magnitude more expensive and nicer, and they take WAY longer to get a fix, and certainly can't function indoors. I'm wondering if this has something to do with the overall precision of the GPS unit. The ones at work claim to be very accurate when they have a fix. This one, not so much. Don't know. More on it later if I dig into it.
I thought that there was something else wrong with the Flight Controller, as I was unable to successfully arm it. Once I got it connected, I was able to use Mission Planner to figure out why it would not arm the ESCs. The error was "RC Not Calibrated". This means it did not think the Radio Control (Transmitter) was calibrated. I calibrated it and wrote the settings down to the Flight Controller, but it still came up as Not Calibrated each time I cycled power. I wondered if maybe the USB port wasn't kicking out enough power to write to the EEPROM or if there was something else wrong with the Flight Controller. After a lot of worry, it turns out that the trim for the throttle was WAY too high. This meant that even at the stick's minimum it couldn't get low enough for Mission Planner to be happy with it. I actually have two trims on my Transmitter, one a fine control, one a gross control. Apparently the gross control had been turned a lot. After fixing that, it armed no problems.
Next time we'll cover connecting the Flight Controller to the Receiver.
