Pixracer DFU needed

Hi all,
I blew my pixracer mcu plugging in an OSD. I did an MCU transplant and used the dfu at
https://pixhawk.org/dev/bootloader_update
and then loaded the arducopter firmware. But this timed out trying to connect in mission planner.
I then found another dfu ( px4fmuv4_bl.dfu) and tried this. This seems to be working fine with the Px4 firmware but won’t connect with arducopter firmware.
Is there a particular bootloader dfu I should be using for the Pixracer? Does anyone have a copy?

Thanks in advance.

I might misunderstand what you’re saying

you just put the bootloader on, and don’t yet have a arducopter firmware, so in e.g. MissionPlanner you next have to go to Install Firmware

I had a read-protected pixracer (clone), and to recover it, I flashed px4fmuv4_bl.bin with SWD, and then ACxxx firmware, and this worked fine for me

Thanks, so I’d need a swd programmer to flash px4fmuv4_bl.bin? Is this different to dfuse demo to upload the px4 dfu? Sorry, I don’t know much about stm’s.

I’ve tried installing both PX4 stack Firmware and Arducopter, PX4 stack is working fine, in both qground control and mission planner.

Transplant… yep been there done that on a NAZE for the same reason , OSD are killers because of the close proximity of 12 & 5 Volts.

Are you loading http://firmware.us.ardupilot.org/Copter/stable/PX4/ ArduCopter-v4.px4 ?

@Takwin
I think it would be helpful if you would be more precise in telling what fails, you let us a bit guessing (screenshots?)

I’ve not used .dfu, but am kind of sure that it should also work with that, i.e. (1) flash px4fmuv4_bl.dfu and then (2) install firmware from Mission Planner

I think you do something which you call “install”, but it’s not step (2)

Ok, I went into mission planner to reinstall arducopter and copy the error messages when connecting as suggested and instead it worked. I don’t know what was different from the other N times I tried. But all seems good now. Thanks :slight_smile: My board is back from the other side.

Cool,
just as curiosity, did you used a hot air reworking tool to remove & replace the STM chip ?

Hot air to remove the chip and drag solder with lots of flux on the cleaned
(as much as possible with braid) up board.

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Hot air to remove the chip and drag solder with lots of flux on the cleaned
(as much as possible with braid) up board.

Next time you do this - could you make a video, please?

You might look at the “PixRacers ALWAYS brick” thread to understand why
people might be interested :slight_smile:

Incidentally, you may be able to use DFU mode on the PixRacer; I’ve never
tried, but the usual short-pin-0 to go into DFU mode might work.

In terms of what to put on - you should be able to compile the bootloader
(https://github.com/ardupilot/Bootloader) readily enough.

sudo dfu-util -a 0 -s 0x08000000 –dfuse-address 0x08000000 -D
px4fmuv2_bl.bin
(adjust as required for v4 etc)

OK, thanks, I’ll look at that post.
I used DFU mode with “DfuSe Demonstration” to upload px4fmuv4_bl.dfu and
that worked well it seems, I shorted the boot pins while uploading the DFU
with solder, removed to install arducopter via mission planner. The board
is up and running fine now.

I read that thread “PixRacers ALWAYS brick” and I have a couple of questions;

my radiolink rc receiver has a i2c to serial converter running off the receiver both powered from the rc in port on the pix. This is working but is it potentially too much power for that port. With the telemetry i2c to serial converter I only have tx and rx going to the telem 1 port. Should I power my receiver and that telemetry board from an external (to the pixracer) 5v source on the same ground?

I don’t want to turn my pixracer into a USB cup warmer again:).

This is the first time I’ve tried a smd project, so I can only tell you what worked for me.

I used a hotair reflow tool, 5-6mm nozzle, low fan speed and about 300C at the center of the chip, while applying gentle lifting pressure to one corner of the chip with a scalpel. It lifted off cleanly and with almost no pressure after about 5-10 secs.

I cleaned up the board with the soldering iron, braid and flux to get the mcu pads as flat as possible.

Using at least 10x magnification I aligned the chip and soldered 2 legs then aligned again and soldered 2 legs on the opposite side.

Finally I drag soldered (with lots of flux) each side of the mcu and checked for bridges the rest is in the previous posts. There are lots of good videos on youtube about drag soldering smd with flux.

BTW. As to the initial problem I had for this post, the culprit turned out to be a dodgy micro sd card that would ocasionally read as present. So the dfu step and arducopter install all worked fine. But with the card not reading the Px4 firmware would connect but of course arducopter wouldn’t.