STM32F411CEu6系统时钟寄存器配置

// ***************************************************************** STM32F411CEu6�� SysClock Max100 RAM 128K FLASH 512K The STM32F4 family incorporates high-speed embedded memories and an extensive range of enhanced I/Os and peripherals connected to two APB buses three AHB buses and a 32-bit multi-AHB bus matrix - 64-Kbyte of CCM (core coupled memory) data RAM - LCD parallel interface, 8080/6800 modes - Timer with quadrature (incremental) encoder input - 5 V-tolerant I/Os - Parallel camera interface - True random number generator - RTC: subsecond accuracy, hardware calendar - 96-bit unique ID // *****************************************************************