This example was tested on STM32L-Discovery and does the following things:
Configure the HSI clock (internal clock)
Configure the GPIOs for driving the LED3 (green - PB7) and LED4 (blue - PB6)
Configure the GPIO for read the Blue Button (PA0) that change the flashing frequency of LED3/4
This examples was tested using:
STM Library Ver. 1.1.1
KEIL Ver. 4.23
IAR Ver. 6.30.6 and 6.30.7.3447
For get this example click here and download the STM32L-Discovery_GPIO_test