Diff: PLL_Config.h

Revision:

0:74d4bbc4ac1e

diff -r 000000000000 -r 74d4bbc4ac1e PLL_Config.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/PLL_Config.h	Sat Jan 05 15:02:22 2019 +0000
@@ -0,0 +1,54 @@
+#include <stm32f4xx.h>
+
+void PLL_Config(void)
+{
+	
+
+//*******************************************************************************
+//*            PLL (clocked by HSI) used as System clock source                	*
+//*							By Stuart MacVeigh									*
+//*******************************************************************************
+
+    RCC->APB1ENR |= RCC_APB1ENR_PWREN;	//enable power interface clock source
+    PWR->CR |= PWR_CR_VOS;
+
+	
+		#define PLL_N	180			//SYSTEM CLOCK SPEED (FCY (MHz))
+		#define HSI		16000000	//INTERAL OSC FREQUENCY
+		
+		#define PLL_M	(HSI/2000000)		//Fcy = Fxtal x PLL_N/(PLL_P x PLL_M)
+		#define PLL_P	2
+		#define PLL_Q	7
+    // HCLK = SYSCLK / 1
+    RCC->CFGR |= RCC_CFGR_HPRE_DIV1;		//CORE CLOCK = 180MHZ
+    
+    // PCLK2 = HCLK / 2
+    RCC->CFGR |= RCC_CFGR_PPRE2_DIV4;		//PERIPHERAL CLOCK 2 = 180MHZ/4 = 45MHZ, THIS IS BECAUSE THE SPI MODULES (AND POSSIBLY OTHERS) DO NOT OPERATE PROPERLY WHEN PCLK > 42MHZ
+    
+    // PCLK1 = HCLK / 4
+    RCC->CFGR |= RCC_CFGR_PPRE1_DIV4;		//PERIPHERAL CLOCK 1 = 180MHZ/4 = 45MHZ, THIS IS BECAUSE THE SPI MODULES (AND POSSIBLY OTHERS) DO NOT OPERATE PROPERLY WHEN PCLK > 42MHZ
+
+    // Configure the main PLL
+    RCC->PLLCFGR = PLL_M | (PLL_N << 6) | (((PLL_P >> 1) -1) << 16) | (PLL_Q << 24);
+
+    // Enable the main PLL
+    RCC->CR |= RCC_CR_PLLON;
+
+    // Wait till the main PLL is ready
+    while(!(RCC->CR & RCC_CR_PLLRDY));
+   
+    // Configure Flash prefetch, Instruction cache, Data cache and wait state
+    FLASH->ACR = FLASH_ACR_ICEN |FLASH_ACR_DCEN |FLASH_ACR_LATENCY_5WS;
+
+    // Select the main PLL as system clock source
+    RCC->CFGR &=~ RCC_CFGR_SW;
+    RCC->CFGR |= RCC_CFGR_SW_PLL;
+
+    // Wait till the main PLL is used as system clock source
+    while ((RCC->CFGR & RCC_CFGR_SWS ) != RCC_CFGR_SWS_PLL);
+	
+//******************************************************************************
+//*            END PLL (CLOCKED BY HSI) SETUP CODE                             *
+//******************************************************************************
+	
+}