Help: Bricked pixhawk?

[Steve McLaughlin]

So I think I went a little too far in my experimentation and temporarily bricked my pixhawk.  I'm looking for the easiest way to recover it.  I don't currently have a JTAG setup so hopefully there's a way w/o needing that but I'm not so sure.

Anyways, this all happened when I started commenting out almost everything in the startup code (HAL_PX4_Class.cpp, main_loop), and forced rc.error to run just before

"Starting APM sensors" in the rc.APM script.  Now the PC doesn't recognize the PixHawk anymore when I plug in the USB.  Both green PWR LEDs light up but the FMU B/E light never lights.  The IO B/E blinks quickly at first then goes solid.  The IO ACT light (blue) then blinks continuously.

Would messing with the startup cause this and is it recoverable?

Thanks,

Steve

[Craig Elder]

Pull the SD card and reboot.  That will bring you to the Nuttx shell and you will be able to re-flash

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[Steve McLaughlin]

Well, this is not working.  Just to confirm...NSH is on PixHawk Serial4/5 secondary pins (as described here: http://pixhawk.org/dev/wiring#ftdi_chip_drivers) and baud rate is 57600?

[Monroe King]

Perhaps if you hold the switch closed and power up it will come up in I/O reload and you can reinstall the firmware that way? It got me back in a Pixhawk I just got that I could not get into. Is it really bricked had like no led's at all?

Monroe

[Craig Elder]

If you remove the SD card the Pixhawk will stop the boot process and not execute the script file to start Ardupilot.  At that point there will be an NSH shell available on the USB serial connection.

You can re-flash the firmware at that point.

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[Steve McLaughlin]

The pixhawk USB is no longer being seen by the PC (no COM port shows up when connected) and it doesn't even look like it's trying.  No USB connect noises or driver not recognized errors or anything...

I've tried multiple computers and multiple cables.  I've tried pulling the SD card and also holding the safety switch on boot.  It's like the USB died.  Is the USB activated in the NuttX, PX4Firmware or ardupilot software in any of the startup scripts or system initialization code?  In other words, can I disable the USB by commenting out lines in the code?

[Robert Lefebvre]

I had something similar happen. The USB just completely stopped working.  The computer didn't know anything was plugged in.  I had sent it back to 3DR for analysis, but Fedex lost the shipment unfortunately.

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[Craig Elder]

Yes, the USB is enabled by Nuttx

It would be interesting if you could connect to the console on Serial 5 with an FTDI cable and watch the messages as the board boots.  

>>>Just to confirm...NSH is on PixHawk Serial4/5 secondary pins (as described here: http://pixhawk.org/dev/wiring#ftdi_chip_drivers) and baud rate is 57600?

that is correct

the pinout is here http://copter.ardupilot.com/wiki/common-pixhawk-overview/#PIXHAWK_Conector_Pin_Assignments

[Monroe King]

Hummm I wonder if a bus pirate would work for this? I can fix any APM but the Pixhawk is a mystery so far. For a while there I was fixing APM's as a service for $20 a pop, just to help out. But the Pixhawk is a new board to me. I'd get the scope out and follow the signals and look for a bad solder joint or missing component at this point. I wonder if 3DR does an ICT on these boards in a Genrad or such? I used to use the Genrad test program for troubleshooting because it allows values to be known in circuit.

[Steve McLaughlin]

I'm kind of doubting its a hardware failure although it's not impossible.  It seems to me I screwed up the initialization enough that the serial ports and USB never get started.  I think I'm going bite the bullet and order a JTAG setup but what a PITA that is on this board...

Does anyone know the NuttX startup script well?  The only thing I can think of doing is somehow putting a good startup script on the sd card and hope it would load that instead of whatever it is using.

[Craig Elder]

The whole point of removing the SD card is that the Pixhawk will boot and give you a command prompt without starting anything else.

[Steve McLaughlin]

This turned out to be a HW fault and had nothing to do with the startup or custom firmware I loaded.

[Craig Elder]

What was the hardware fault?

On Sep 25, 2014 8:50 AM, "'Steve McLaughlin' via drones-discuss" <drones-...@googlegroups.com> wrote:

This turned out to be a HW fault and had nothing to do with the startup or custom firmware I loaded.

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[Steve McLaughlin]

I'm not 100% sure, but it looks like the FMU chip.  Something was pulling down the 3.3v reg to 0.3v and I measured 11ohms across one of the power pins to GND of the main STM32 chip.

btw...this board was not built by 3DR.

[Craig Elder]

In the future it woukd be good to mention that upfront.

On Sep 25, 2014 9:29 AM, "'Steve McLaughlin' via drones-discuss" <drones-...@googlegroups.com> wrote:

I'm not 100% sure, but it looks like the FMU chip.  Something was pulling down the 3.3v reg to 0.3v and I measured 11ohms across one of the power pins to GND of the main STM32 chip.

btw...this board was not built by 3DR.

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[Steve McLaughlin]

I apologize.  I was under the assumption I had a software issue so I didn't think to mention that.