ST-LINK flash and debug on the SPRacingF3

I was having trouble flashing BetaFlight to my SPRacingF3 board, so I used the SWD port to load the firmware.

First build the binary with the following command. I'm using a SPRACINGF3 target. Switch this to match whatever target you're working with:

make TARGET=SPRACINGF3

Then, from the same directory where you built the binary, flash it with:

openocd -f ~/Desktop/stm32f3.cfg -c "program ./obj/main/betaflight_SPRACINGF3.elf verify reset exit"

Where stm32f3.cfg contains:

› cat ~/Desktop/stm32f3.cfg
# This is an STM32F3 discovery board with a single STM32F303VCT6 chip.
# http://www.st.com/internet/evalboard/product/254044.jsp

source [find interface/stlink-v2.cfg]

transport select hla_swd

source [find target/stm32f3x.cfg]

reset_config none separate

The key line in that file is the last line: reset_config none separate.

If you have trouble getting the board to reset, you'll see an error like this:

timed out while waiting for target halted
TARGET: stm32f3x.cpu - Not halted
in procedure 'reset'
in procedure 'ocd_bouncer'

By default the config is set to use the RESET pin.

Instead, send the reset command over the SWD pins with:

reset_config none separate

see here for more