Hello guys,
I’m having this behavior (video) on my 1 year-old Pixhawk. My pc doesn’t recognize it anymore, neither on other PCs and other USB cables. What seems to be the problem? I can’t finish my MSc thesis with this 0-luck right-on-time inconvenient problem!
Please help me 
Thank you very much!
My first thought is that the drivers for the PC computer need to be re-installed, (which is done when Mission Planner is installed).
If the USB port connector is damaged somehow, it may be possible to use the DF13-4pin USB connection on the top of the Pixhawk.
If the USB port does not work at all it may still be possible to connect to the telemetry #1 port using a FTDI USB->TTL serial port adapter. However, if the Pixhawk serial (telemetry) port(s) are not already configured for telemetry, then this won’t either.
I’m not certain if the telemetry serial port is set active by default when firmware is loaded.
Use a serial terminal on the PC to see if there data on the telemetry ports, even if the baud rate doesn’t match there should be garbage data if the baud rates are close. Then knowing that there is data coming from the telemetry port you may be able to connect using AUTO-baud rate selection in Mission planner or use a trial & error approach by trying to make a connection with every possible baud rate choice. The usual telemetry baud is 57600.
I’m making the assumption that you are familiar with pin-out connections for the Pixhawk.
To use the DF13 USB connection without the 3DR kit you will probably have to sacrifice a standard USB cable to wire it to a 4-pin DF13 connector. Be careful to check the connections with a multi-meter before plugging it in.
FTDI TTL serial port cables come in different voltage flavours, 5V & 3.3V use a 3.3 volt version.
Chris
Hey Chris,
Thank you for your answer, but right know i tryed to connect FTDI USB <-> TTL serial (to telemtry port on Pix) and when i used kermit, connect (to flash bootloader, i need to acess NSH, and since i don’t have an USB detection as normal, i need to try these method) and i see strange ‘?’ characters poping up, but no connection to NSH. I’ll tryed with Mission Planner, sucessfuly opened com port on terminal, but then no response from terminal (don’t know why). I think my Pix is plain dead, and it was by a faulty USB cable for sure. It’s the only reason. APM2.5 is working just fine, and btw APM survived so many crashes and voltage spikes than Pixhawk. It’s a shame!
Thank you Chris once more for your complete quick answer 
I have exactly the same problem. Both power led solid green, both B/E led solid amber and act led blinking blue. the pixhawk was working fine after first installation of the firmware (i actually used the PIX4), but while calibrating the compass and sensors with telemetri connection, it stop to work and trying to turn it on again, it appear like in your video. I try to understand what happened from the SD, but is not readable from the mac and from windows anymore. I used a new formatted FAT32 sd card (8b HC of Sandisc) and it doesn’t change anything. Please inform me if you solved the problem in some way or if you discovered what happened.
thank you
I have the same problem. I were also calibrating the compass and sensors with telemetry connection, and it stopped working. Has anyone found a solution for this bug?