[nathanwiebe]

Ok, I believe I have figured out what is up with the UART GDB stub.  The NodeMCU v2 board controls the RESET and GPIO0/BOOT pins using the USB-UART chip’s flow control outputs (DTR and RTS) – this is the behavior of many many Arduino- and NodeMCU-compatible ESP8266 boards out there, and there is a de facto standard for the pin assignment used by Arduino Studio, VisualMicro, etc.  VisualGDB seems to set the flow control pins in a state that results in GPIO0 being held low, so the micro never boots into run mode after programming.  I do wish VisualGDB could be modified to either support the controlling of these pins via the standard pinout (i.e. have an option to automatically control reset and boot via these pins without having to prompt the user to enter boot mode), or leave them in a state that is compatible with BOOT floating high (so the RTS pin doesn’t override the button on the BOOT pin.)

For now, I am using another dev board I have that doesn’t use the USB-UART flow control pins for controlling RESET and BOOT.

Now…. on to troubleshooting why my JTAG connection isn’t working… (btw I did try the NOFLASH option during my original testing with identical results to the other options.  Thanks for the suggestion though… I will stick to that option until I get up and running on JTAG)

[nathanwiebe]

As promised, here is the GDB log from the UART GDB Stub attempts:

Your VisualGDB trial expires in 30 days!
C:\SysGCC\esp8266\bin\xtensa-lx106-elf-gdb.exe –interpreter mi C:\Projects\ESP_UARTGDBStub\ESP_UARTGDBStub/Debug/ESP_UARTGDBStub.elf
-gdb-version
=thread-group-added,id=”i1″
GNU gdb (GDB) 7.11
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html&gt;
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type “show copying”
and “show warranty” for details.
This GDB was configured as “–host=i686-pc-mingw32 –target=xtensa-lx106-elf”.
Type “show configuration” for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/&gt;.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/&gt;.
For help, type “help”.
Type “apropos word” to search for commands related to “word”…
Reading symbols from C:\Projects\ESP_UARTGDBStub\ESP_UARTGDBStub/Debug/ESP_UARTGDBStub.elf…
done.
GNU gdb (GDB) 7.11
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html&gt;
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type “show copying”
and “show warranty” for details.
This GDB was configured as “–host=i686-pc-mingw32 –target=xtensa-lx106-elf”.
Type “show configuration” for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/&gt;.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/&gt;.
For help, type “help”.
Type “apropos word” to search for commands related to “word”.
OK
-list-features
^done,features=[“frozen-varobjs”,”pending-breakpoints”,”thread-info”,”data-read-memory-bytes”,”breakpoint-notifications”,”ada-task-info”,”language-option”,”info-gdb-mi-command”,”undefined-command-error-code”,”exec-run-start-option”]
-gdb-set stop-on-solib-events 1
OK
-gdb-set disassembly-flavor intel
No symbol “disassembly” in current context.
-gdb-set print demangle off
OK
-break-insert -f main
&”Function \”main\” not defined.\n”
^done,bkpt={number=”1″,type=”breakpoint”,disp=”keep”,enabled=”y”,addr=”<PENDING>”,pending=”main”,times=”0″,original-location=”main”}
Warning: could not set a breakpoint on main. ‘Step into new instance’ will not work.
-break-delete 1
OK
set serial baud 74800
&”set serial baud 74800\n”
=cmd-param-changed,param=”serial baud”,value=”74800″
OK
target remote \\.\COM3
&”target remote \\\\.\\COM3\n”
Remote debugging using \\.\COM3
Loaded image in 10649 ms
&”Quit (expect signal SIGINT when the program is resumed)\n”
Quit (expect signal SIGINT when the program is resumed)
System.Exception: GDB has exited prematurely

at VisualGDB.GDBDebugEngine.a(adv A_0)

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