A "Hello World" blinky example that activates that shows startup code and sets up the clock to multiply the external HSE clock from 8 MHz to a 36 MHz system clock using the PLL. Blinking frequency is around 1 Hz.
This has been compiled with gcc-7.3.0 and a minimal newlib configuration (not necessary for the example, however). The STM32 standard peripheral library is used for setting up GPIOs and needs to be downloaded externally from STmicroelectronics: STM32F1 Standard Peripheral Library
GNU GPL-3.