It’s often tricky to know what’s happening inside a microcontroller when everything is not going as planned. This post is about enabling GDB with chips providing the SWD interface, e.g. STM32 chips.
For this you need an SWD dongle. If you are up to some DIY and want it cheap, check the previous post about modifying STM32 Discovery for the purpose.
You can get the patched (thanks Simon Qian!) OpenOCD from our Github repository: https://github.com/snowcap-electronics/OpenOCD-SWD
Fetch, compile and install it to /usr/local/openocd with:
git clone https://github.com/snowcap-electronics/OpenOCD-SWD.git cd OpenOCD-SWD ./bootstrap ./configure --enable-maintainer-mode --enable-vsllink --prefix=/usr/local/openocd make -j4 make install
To program a new software to the F1 Discovery’s F100, connect CN3 pin 1&4 and 2&3. This allows SWD communication from the ST-Link’s F103 to the Discovery’s F100.
sudo /usr/local/openocd/bin/openocd -f interface/vsllink-swd.cfg -f target/stm32f1x.cfg
You should get something like this:
Open On-Chip Debugger 0.6.0-dev-00247-g1981fa8 (2011-11-20-16:55) Licensed under GNU GPL v2 For bug reports, read http://openocd.sourceforge.net/doc/doxygen/bugs.html Warn : must select a transport. Info : OpenOCD runs in SWD mode 1000 kHz adapter_nsrst_delay: 100 jtag_ntrst_delay: 100 cortex_m3 reset_config sysresetreq Info : Versaloon(0x33)by Simon(compiled on Oct 25 2011) Info : USB_TO_XXX abilities: 0x00000008:0x00000040:0xC0000006 Info : clock speed 1000 kHz Info : stm32.cpu: hardware has 6 breakpoints, 4 watchpoints Error: stm32.cpu -- clearing lockup after double fault Polling target failed, GDB will be halted. Polling again in 100ms Polling succeeded again
Then start GDB in another window:
arm-none-eabi-gdb -ex "target remote localhost:3333" firmware.elf
And program it to the F100′s flash: