\begin{lstlisting}[language=make]
# If no BOARD is found in the environment, use this default:
BOARD ?= bluepill

# To use chinese st-link v2 and ch340 dongle with bluepill
ifeq ($(BOARD),bluepill)
STLINK_VERSION=2
PORT_LINUX=/dev/ttyUSB0
endif
\end{lstlisting}
