Using a Raspberry Pi3 as an OpenOCD server

Cheap and plentiful, a Raspberry Pi3 makes an excellent OpenOCD server. You can place it near your target and just attach to it from where you do your builds. On my Pi3 server I have openocd-0.9.0 and openocd-0.10.0, the win with a Pi3 is it has WLAN, so permit it to sign on to your network, preferably with a known static IP, and then you can ssh over to it and start openocd:

root@pi3:~/openocd-0.10.0/tcl# ../src/openocd --file board/st_nucleo_l476rg.cfg
Open On-Chip Debugger 0.10.0
Licensed under GNU GPL v2
For bug reports, read
        http://openocd.org/doc/doxygen/bugs.html
Info : The selected transport took over low-level target control. The results mi
ght differ compared to plain JTAG/SWD
adapter speed: 480 kHz
adapter_nsrst_delay: 100
none separate
srst_only separate srst_nogate srst_open_drain connect_deassert_srst
Info : clock speed 480 kHz
Info : STLINK v2 JTAG v25 API v2 SWIM v14 VID 0x0483 PID 0x374B
Info : using stlink api v2
Info : Target voltage: 3.262028
Info : stm32l4x.cpu: hardware has 6 breakpoints, 4 watchpoints

Now you have a connection to your board.

On another machine where you do your dev, (in my case a box in an upstairs server room) you just allow GDB to connect to it via the static IP:

admin@ubuntu_1604:/.share/CACHEDEV1_DATA/Ada/STM32/L432/dac_sw$ arm-eabi-gdb obj
/Debug/dac_sw
GNU gdb (GDB) 7.10 for GNAT GPL 2016 [rev=gdb-7.10-ref-161-g9bf8eca]
Copyright (C) 2015 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
See your support agreement for details of warranty and support.
If you do not have a current support agreement, then there is absolutely
no warranty for this version of GDB.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "--host=i686-pc-linux-gnu --target=arm-eabi".
Type "show configuration" for configuration details.For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from obj/Debug/dac_sw...done.
(gdb) target extended-remote 10.0.1.241:3333
Remote debugging using 10.0.1.241:3333
0x00000000 in ?? ()
(gdb) monitor reset halt
Unable to match requested speed 500 kHz, using 480 kHz
Unable to match requested speed 500 kHz, using 480 kHz

adapter speed: 480 kHz

target halted due to debug-request, current mode: Thread

xPSR: 0x01000000 pc: 0x08004420 msp: 0x200006d0

(gdb) load

Loading section .text, size 0xc2e4 lma 0x8000000

Loading section .ARM.extab, size 0x7c4 lma 0x800c2e4

Loading section .ARM.exidx, size 0xaa0 lma 0x800caa8

Loading section .rodata, size 0x1d50 lma 0x800d548

Loading section .data, size 0x2c4 lma 0x800f298

Start address 0x8007348, load size 62812

Transfer rate: 22 KB/sec, 7851 bytes/write.

(gdb) monitor reset init

Unable to match requested speed 500 kHz, using 480 kHz

Unable to match requested speed 500 kHz, using 480 kHz

adapter speed: 480 kHz

target halted due to debug-request, current mode: Thread

xPSR: 0x01000000 pc: 0x08007348 msp: 0x2000cb20

adapter speed: 4000 kHz

(gdb) b main

Breakpoint 1 at 0x80007b6: file b__dac_sw.adb, line 176.

(gdb) b __gnat_last_chance_handler

Breakpoint 2 at 0x800a0be

(gdb) c

Continuing.

Note: automatically using hardware breakpoints for read-only addresses.

Breakpoint 1, main () at b__dac_sw.adb:176

176           Ensure_Reference : aliased System.Address := Ada_Main_Program_Name

'Address;

(gdb)

The real win is you have 4 USB ports for connections to targets. Also the Adafruit SiLabs USB<->RS232 dongle works well so you can get UART data from an embedded target. With a Pi2 you lose one USB port for the WLAN dongle.

Here seen connected to the STM32L432 nucleo and is the target from the session show above. Also in the light blue housing we see the Adafruit usb to ttl serial cable.

https://www.adafruit.com/product/954