zephyr/boards/arm/stm32_min_dev/stm32_min_dev_defconfig

CONFIG_ARM=y
CONFIG_BOARD_STM32_MIN_DEV=y
CONFIG_SOC_SERIES_STM32F1X=y
CONFIG_SOC_STM32F103X8=y
CONFIG_CORTEX_M_SYSTICK=y

# 72MHz system clock
CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC=72000000

# enable uart driver
CONFIG_SERIAL=y

# enable console
CONFIG_CONSOLE=y
CONFIG_UART_CONSOLE=y

# enable pinmux
CONFIG_PINMUX=y

# enable GPIO
CONFIG_GPIO=y

# clock configuration
CONFIG_CLOCK_CONTROL=y
CONFIG_CLOCK_STM32_HSE_CLOCK=8000000
CONFIG_CLOCK_STM32_SYSCLK_SRC_PLL=y

# use HSE as PLL input
CONFIG_CLOCK_STM32_PLL_SRC_HSE=y
# produce 72MHz clock at PLL output
CONFIG_CLOCK_STM32_PLL_XTPRE=n
CONFIG_CLOCK_STM32_PLL_MULTIPLIER=9
CONFIG_CLOCK_STM32_AHB_PRESCALER=1

# APB1 clock must not exceed 36MHz limit
CONFIG_CLOCK_STM32_APB1_PRESCALER=2
CONFIG_CLOCK_STM32_APB2_PRESCALER=1