Introduction - If you have any usage issues, please Google them yourself
The main routine test LED KEY, when the program runs on the LCD screen will display: The STM32F10x DEMO GPIO TEST key K1-K4 control the number of lights flashing: k1, L1, L3 each flash once k2, L1 L3 flash 2 times each press k3, L1, L3 flash 3 times each k4, L1, L3 flash four times each