Re: [Paparazzi-devel] olimex stm32f405 bootloader strange behaviour

[Chris]

Hi Sergey
Yes i just found out what is going on.
I can bypass the problem if i swap ports for gps and modem as the modem 
does not send anything on startup or i can change the pcb i use in order 
to power modem and gps for the servo +5v.
This way when the usb plug is inserted, the modem and gps will not have 
power since the main battery will be disconnected.
Chris

On 11/04/2014 08:45 PM, Sergey Krukowski wrote:
> Actually during bootloader startup some defined inputs has to be hold 
> either hight or low. Otherwise the bootloader think there is a signal 
> on other input (not USB) and starts in non USB mode.
> Looks like your GPS send some data on bootloaders input during startup 
> and it tries to start in UART mode. It's not bad, just bootloaders 
> feature.
>
> Best regards,
> Sergey
>
> > Hi.
> > I came across a strange problem while experimenting with the olimex 
> > stm32f405 board.
> > When nothing is connected to the board everything works fine and the 
> > dfu-util uploads the code.
> > As soon as i try to upload the code but with the gps connected 
> > (obviously powered from the usb +5v)
> > dfu-util cannot find  the bootloader and more importand the dmesg 
> > command shows that the usb device cannot be enumerated.
> > Now either the gps (ublox NEO7) with active antenna and superb 
> > sensitivity is jamming the usb signals via
> > the usb power line or something else is happening.
> > I will try with another gps also but i thought that maybe someone has 
> > encountered this behaviour also.
> > The discovery board does not have this problem with the same gps but 
> > i will test it again just to be sure
> > as i haven't seen anything like this before (i also changed the gps 
> > uart in the airframe file and it still does it)
> > Chris
> >
> >
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