Core Dump and Bluetooth issues

[ThomasZ2196]

Hello everyone !

I need for my work to be able to control a LoPy4 board using a phone. So I'm currently looking to pair the LoPy4 with my phone (Samsung Galaxy S9).

I'm not used with this kind of board so I'm following the bluetooth chapter of the pycom docs. But when I upload this code :

import ubinascii
from network import Bluetooth

bluetooth = Bluetooth()
bluetooth.start_scan(20)

A core dump error loop occured and I can't upload any new code without reset the board with the firmware plugin. Here the end of core dump error :

Guru Meditation Error: Core  0 panic'ed (LoadProhibited). Exception was unhandled.
Core 0 register dump:
PC      : 0x401ef77f  PS      : 0x00060430  A0      : 0x801e0e01  A1      : 0x3ffee9e0  
A2      : 0xa4d59534  A3      : 0x3fbc1eec  A4      : 0x00060420  A5      : 0x3ffeeaa0  
A6      : 0x0000000c  A7      : 0x3ffbafd4  A8      : 0xb33fffff  A9      : 0x0000cdcd  
A10     : 0x3ffeb550  A11     : 0x401c027c  A12     : 0xb33fffff  A13     : 0x0000cdcd  
A14     : 0x000000aa  A15     : 0x3ffeb510  SAR     : 0x0000000d  EXCCAUSE: 0x0000001c  
EXCVADDR: 0xa4d59534  LBEG    : 0x400934c4  LEND    : 0x400934f2  LCOUNT  : 0x00000000  

ELF file SHA256: 0000000000000000000000000000000000000000000000000000000000000000

Backtrace: 0x401ef77f:0x3ffee9e0 0x401e0dfe:0x3ffeea50 0x401e12bd:0x3ffeea70 0x401cd10e:0x3ffeea90

Maybe I forgot one step ?

Thank you in advance for your help !

[Gijs]

Hi,
I cannot reproduce the error using your example. Can you tell me the firmware version you are running by using

>>>import os
>>>os.uname() 

(Try to update to the latest firmware version)
But you can use safe boot to disable the main.py and boot.py so you can upload new code. This page: https://docs.pycom.io/gettingstarted/programming/safeboot/ explains more on how to do this.
Best

[ThomasZ2196]

Hi, I'm using the 1.20.2.rc10 firmware version.

[Gijs]

Which firmware version are you using? Pybytes or Pygate?
Is pybytes activated on boot or no?
Can you submit the whole stack trace (from power on reset to coredump and on)?
Is your power supply maybe at fault here? Are you able to supply enough current?

This basic example should work on any device without errors, so I am wondering what is different in your case..