/*
* Step #2: select the crystal value (XTAL) and oscillator source
* (OSCSRC), and clear the PWRDN bit in RCC/RCC2. Setting the XTAL
/*
* Step #2: select the crystal value (XTAL) and oscillator source
* (OSCSRC), and clear the PWRDN bit in RCC/RCC2. Setting the XTAL