LPC1788启动代码分析
2017-08-09 21:59
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/**********************************************************************
* $Id$ system_LPC177x_8x.c
2011-06-02
*//**
* @file system_LPC177x_8x.c
* @brief CMSIS Cortex-M3 Device Peripheral Access Layer Source File
* for the NXP LPC177x_8x Device Series
*
* ARM Limited (ARM) is supplying this software for use with
* Cortex-M processor based microcontrollers. This file can be
* freely distributed within development tools that are supporting
* such ARM based processors.
*
* @version 1.0
* @date 02. June. 2011
* @author NXP MCU SW Application Team
*
* Copyright(C) 2011, NXP Semiconductor
* All rights reserved.
*
***********************************************************************
* Software that is described herein is for illustrative purposes only
* which provides customers with programming information regarding the
* products. This software is supplied "AS IS" without any warranties.
* NXP Semiconductors assumes no responsibility or liability for the
* use of the software, conveys no license or title under any patent,
* copyright, or mask work right to the product. NXP Semiconductors
* reserves the right to make changes in the software without
* notification. NXP Semiconductors also make no representation or
* warranty that such application will be suitable for the specified
* use without further testing or modification.
* Permission to use, copy, modify, and distribute this software and its
* documentation is hereby granted, under NXP Semiconductors'
* relevant copyright in the software, without fee, provided that it
* is used in conjunction with NXP Semiconductors microcontrollers. This
* copyright, permission, and disclaimer notice must appear in all copies of
* this code.
**********************************************************************/
#include <stdint.h>
#include "LPC177x_8x.h"
#include "system_LPC177x_8x.h"
/** @addtogroup LPC177x_8x_System
* @{
*/
#define __CLK_DIV(x,y) (((y) == 0) ? 0: (x)/(y))
/*
//-------- <<< Use Configuration Wizard in Context Menu >>> ------------------
*/
/*--------------------- Clock Configuration ----------------------------------
//
// <e>
Clock Configuration
// <h>
System Controls and Status Register (SCS - address 0x400F C1A0)
// <o1.0>
EMC Shift Control Bit
// <i>
Controls how addresses are output on the EMC address pins for static memories
// <0=>
Static CS addresses match bus width; AD[1] = 0 for 32 bit, AD[0] = 0 for 16+32 bit (Bit 0 is 0)
// <1=>
Static CS addresses start at LSB 0 regardless of memory width (Bit 0 is 1)
//
// <o1.1>
EMC Reset Disable Bit
// <i>
If 0 (zero), all registers and functions of the EMC are initialized upon any reset condition
// <i>
If 1, EMC is still retained its state through a warm reset
// <0=>
Both EMC resets are asserted when any type of chip reset event occurs (Bit 1 is 0)
// <1=>
Portions of EMC will only be reset by POR or BOR event (Bit 1 is 1)
//
// <o1.2>
EMC Burst Control
// <i>
Set to 1 to prevent multiple sequential accesses to memory via EMC static memory chip selects
// <0=>
Burst enabled (Bit 2 is 0)
// <1=>
Bust disbled (Bit 2 is 1)
//
// <o1.3>
MCIPWR Active Level
// <i>
Selects the active level for the SD card interface signal SD_PWR
// <0=>
SD_PWR is active low (inverted output of the SD Card interface block) (Bit 3 is 0)
// <1=>
SD_PWR is active high (follows the output of the SD Card interface block) (Bit 3 is 1)
//
// <o1.4>
Main Oscillator Range Select
// <0=>
In Range 1 MHz to 20 MHz (Bit 4 is 0)
// <1=>
In Range 15 MHz to 25 MHz (Bit 4 is 1)
//
// <o1.5>
Main Oscillator enable
// <i>
0 (zero) means disabled, 1 means enable
//
// <o1.6>
Main Oscillator status (Read-Only)
// </h>
//
// <h>
Clock Source Select Register (CLKSRCSEL - address 0x400F C10C)
// <o2.0>
CLKSRC: Select the clock source for sysclk to PLL0 clock
// <0=>
Internal RC oscillator (Bit 0 is 0)
// <1=>
Main oscillator (Bit 0 is 1)
// </h>
//
// <e3>PLL0 Configuration (Main PLL PLL0CFG - address 0x400F C084)
// <i>
F_in is in the range of 1 MHz to 25 MHz
// <i>
F_cco = (F_in * M * 2 * P) is in range of 156 MHz to 320 MHz
// <i>
PLL out clock = (F_cco / (2 * P)) is in rane of 9.75 MHz to 160 MHz
//
// <o4.0..4> MSEL: PLL Multiplier Value
// <i>
M Value
// <1-32><#-1>
//
// <o4.5..6>
PSEL: PLL Divider Value
// <i>
P Value
// <0=> 1
// <1=>
2
// <2=>
4
// <3=>
8
// </e>
//
// <e5>PLL1 Configuration (Alt PLL PLL1CFG - address 0x400F C0A4)
// <i>
F_in is in the range of 1 MHz to 25 MHz
// <i>
F_cco = (F_in * M * 2 * P) is in range of 156 MHz to 320 MHz
// <i>
PLL out clock = (F_cco / (2 * P)) is in rane of 9.75 MHz to 160 MHz
//
// <o6.0..4> MSEL: PLL Multiplier Value
// <i>
M Value
// <1-32><#-1>
//
// <o6.5..6>
PSEL: PLL Divider Value
// <i>
P Value
// <0=>
1
// <1=>
2
// <2=>
4
// <3=>
8
// </e>
//
// <h>
CPU Clock Selection Register (CCLKSEL - address 0x400F C104)
// <o7.0..4>
CCLKDIV: Select the value for divider of CPU clock (CCLK)
// <i>
0: The divider is turned off. No clock will be provided to the CPU
// <i>
n: The input clock is divided by n to produce the CPU clock
// <0-31>
//
// <o7.8>
CCLKSEL: Select the input to the divider of CPU clock
// <0=>
sysclk clock is used
// <1=>
Main PLL0 clock is used
// </h>
//
// <h>
USB Clock Selection Register (USBCLKSEL - 0x400F C108)
// <o8.0..4>
USBDIV: USB clock (source PLL0) divider selection
// <0=>
Divider is off and no clock provides to USB subsystem
// <4=>
Divider value is 4 (The source clock is divided by 4)
// <6=>
Divider value is 6 (The source clock is divided by 6)
//
// <o8.8..9>
USBSEL: Select the source for USB clock divider
// <i>
When CPU clock is selected, the USB can be accessed
// <i>
by software but cannot perform USB functions
// <0=>
sysclk clock (the clock input to PLL0)
// <1=>
The clock output from PLL0
// <2=>
The clock output from PLL1
// </h>
//
// <h>
EMC Clock Selection Register (EMCCLKSEL - address 0x400F C100)
// <o9.0>
EMCDIV: Set the divider for EMC clock
// <0=> Divider value is 1
// <1=> Divider value is 2 (EMC clock is equal a half of input clock)
// </h>
//
// <h>
Peripheral Clock Selection Register (PCLKSEL - address 0x400F C1A8)
// <o10.0..4>
PCLKDIV: APB Peripheral clock divider
// <i>
0: The divider is turned off. No clock will be provided to APB peripherals
// <i>
n: The input clock is divided by n to produce the APB peripheral clock
// <0-31>
// </h>
//
// <h>
Power Control for Peripherals Register (PCONP - address 0x400F C1C8)
// <o11.0>
PCLCD: LCD controller power/clock enable (bit 0)
// <o11.1>
PCTIM0: Timer/Counter 0 power/clock enable (bit 1)
// <o11.2>
PCTIM1: Timer/Counter 1 power/clock enable (bit 2)
// <o11.3>
PCUART0: UART 0 power/clock enable (bit 3)
// <o11.4>
PCUART1: UART 1 power/clock enable (bit 4)
// <o11.5>
PCPWM0: PWM0 power/clock enable (bit 5)
// <o11.6>
PCPWM1: PWM1 power/clock enable (bit 6)
// <o11.7>
PCI2C0: I2C 0 interface power/clock enable (bit 7)
// <o11.8>
PCUART4: UART 4 power/clock enable (bit 8)
// <o11.9>
PCRTC: RTC and Event Recorder power/clock enable (bit 9)
// <o11.10>
PCSSP1: SSP 1 interface power/clock enable (bit 10)
// <o11.11>
PCEMC: External Memory Controller power/clock enable (bit 11)
// <o11.12>
PCADC: A/D converter power/clock enable (bit 12)
// <o11.13>
PCCAN1: CAN controller 1 power/clock enable (bit 13)
// <o11.14>
PCCAN2: CAN controller 2 power/clock enable (bit 14)
// <o11.15>
PCGPIO: IOCON, GPIO, and GPIO interrupts power/clock enable (bit 15)
// <o11.17>
PCMCPWM: Motor Control PWM power/clock enable (bit 17)
// <o11.18>
PCQEI: Quadrature encoder interface power/clock enable (bit 18)
// <o11.19>
PCI2C1: I2C 1 interface power/clock enable (bit 19)
// <o11.20>
PCSSP2: SSP 2 interface power/clock enable (bit 20)
// <o11.21>
PCSSP0: SSP 0 interface power/clock enable (bit 21)
// <o11.22>
PCTIM2: Timer 2 power/clock enable (bit 22)
// <o11.23>
PCTIM3: Timer 3 power/clock enable (bit 23)
// <o11.24>
PCUART2: UART 2 power/clock enable (bit 24)
// <o11.25>
PCUART3: UART 3 power/clock enable (bit 25)
// <o11.26>
PCI2C2: I2C 2 interface power/clock enable (bit 26)
// <o11.27>
PCI2S: I2S interface power/clock enable (bit 27)
// <o11.28>
PCSDC: SD Card interface power/clock enable (bit 28)
// <o11.29>
PCGPDMA: GPDMA function power/clock enable (bit 29)
// <o11.30>
PCENET: Ethernet block power/clock enable (bit 30)
// <o11.31>
PCUSB: USB interface power/clock enable (bit 31)
// </h>
//
// <h>
Clock Output Configuration Register (CLKOUTCFG)
// <o12.0..3>
CLKOUTSEL: Clock Source for CLKOUT Selection
// <0=>
CPU clock
// <1=>
Main Oscillator
// <2=>
Internal RC Oscillator
// <3=>
USB clock
// <4=>
RTC Oscillator
// <5=>
unused
// <6=>
Watchdog Oscillator
//
// <o12.4..7>
CLKOUTDIV: Output Clock Divider
// <1-16><#-1>
//
// <o12.8>
CLKOUT_EN: CLKOUT enable
// </h>
//
// </e>
*/
/** @addtogroup LPC177x_8x_System_Defines LPC177x_8x System Defines
@{
*/
#define CLOCK_SETUP 1
#define SCS_Val 0x00000021
#define CLKSRCSEL_Val 0x00000001
#define PLL0_SETUP 1
#define PLL0CFG_Val 0x00000009
#define PLL1_SETUP 1
#define PLL1CFG_Val 0x00000023
#define CCLKSEL_Val 0x00000101
#define USBCLKSEL_Val 0x00000201
#define EMCCLKSEL_Val 0x00000001
#define PCLKSEL_Val 0x00000002
#define PCONP_Val 0x042887DE
#define CLKOUTCFG_Val 0x00000100
/*--------------------- Flash Accelerator Configuration ----------------------
//
// <e>
Flash Accelerator Configuration register (FLASHCFG - address 0x400F C000)
// <o1.12..15>
FLASHTIM: Flash Access Time
// <0=>
1 CPU clock (for CPU clock up to 20 MHz)
// <1=>
2 CPU clocks (for CPU clock up to 40 MHz)
// <2=>
3 CPU clocks (for CPU clock up to 60 MHz)
// <3=>
4 CPU clocks (for CPU clock up to 80 MHz)
// <4=>
5 CPU clocks (for CPU clock up to 100 MHz)
// <5=>
6 CPU clocks (for any CPU clock)
// </e>
*/
#define FLASH_SETUP 1
#define FLASHCFG_Val 0x00005000
/*
//-------- <<< end of configuration section >>> ------------------------------
*/
/*----------------------------------------------------------------------------
Check the register settings
*----------------------------------------------------------------------------*/
#define CHECK_RANGE(val, min, max) ((val < min) || (val > max))
#define CHECK_RSVD(val, mask) (val & mask)
/* Clock Configuration -------------------------------------------------------*/
#if (CHECK_RSVD((SCS_Val), ~0x0000003F))
#error "SCS: Invalid values of reserved bits!"
#endif
#if (CHECK_RANGE((CLKSRCSEL_Val), 0, 1))
#error "CLKSRCSEL: Value out of range!"
#endif
#if (CHECK_RSVD((PLL0CFG_Val), ~0x0000007F))
#error "PLL0CFG: Invalid values of reserved bits!"
#endif
#if (CHECK_RSVD((PLL1CFG_Val), ~0x0000007F))
#error "PLL1CFG: Invalid values of reserved bits!"
#endif
#if (CHECK_RSVD((CCLKSEL_Val), ~0x0000011F))
#error "CCLKSEL: Invalid values of reserved bits!"
#endif
#if (CHECK_RSVD((USBCLKSEL_Val), ~0x0000031F))
#error "USBCLKSEL: Invalid values of reserved bits!"
#endif
#if (CHECK_RSVD((EMCCLKSEL_Val), ~0x00000001))
#error "EMCCLKSEL: Invalid values of reserved bits!"
#endif
#if (CHECK_RSVD((PCLKSEL_Val), ~0x0000001F))
#error "PCLKSEL: Invalid values of reserved bits!"
#endif
#if (CHECK_RSVD((PCONP_Val), ~0xFFFEFFFF))
#error "PCONP: Invalid values of reserved bits!"
#endif
#if (CHECK_RSVD((CLKOUTCFG_Val), ~0x000001FF))
#error "CLKOUTCFG: Invalid values of reserved bits!"
#endif
/* Flash Accelerator Configuration -------------------------------------------*/
#if (CHECK_RSVD((FLASHCFG_Val), ~0x0000F000))
#warning "FLASHCFG: Invalid values of reserved bits!"
#endif
/*----------------------------------------------------------------------------
DEFINES
*----------------------------------------------------------------------------*/
/* pll_out_clk = F_cco / (2 ?P)
F_cco = pll_in_clk ?M ?2 ?P */
#define __M ((PLL0CFG_Val & 0x1F) + 1)
#define __PLL0_CLK(__F_IN) (__F_IN * __M)
#define __CCLK_DIV (CCLKSEL_Val & 0x1F)
#define __PCLK_DIV (PCLKSEL_Val & 0x1F)
#define __ECLK_DIV ((EMCCLKSEL_Val & 0x01) + 1)
/* Determine core clock frequency according to settings */
#if (CLOCK_SETUP) /* Clock Setup */
#if ((CLKSRCSEL_Val & 0x01) == 1) && ((SCS_Val & 0x20)== 0)
#error "Main Oscillator is selected as clock source but is not enabled!"
#endif
#if ((CCLKSEL_Val & 0x100) == 0x100) && (PLL0_SETUP == 0)
#error "Main PLL is selected as clock source but is not enabled!"
#endif
#if ((CCLKSEL_Val & 0x100) == 0) /* cclk = sysclk */
#if ((CLKSRCSEL_Val & 0x01) == 0) /* sysclk = irc_clk */
#define __CORE_CLK (IRC_OSC / __CCLK_DIV)
#define __PER_CLK (IRC_OSC/ __PCLK_DIV)
#define __EMC_CLK (__CORE_CLK/ __ECLK_DIV)
#else /* sysclk = osc_clk */
#define __CORE_CLK (OSC_CLK / __CCLK_DIV)
#define __PER_CLK (OSC_CLK/ __PCLK_DIV)
#define __EMC_CLK (__CORE_CLK/ __ECLK_DIV)
#endif
#else /* cclk = pll_clk */
#if ((CLKSRCSEL_Val & 0x01) == 0) /* sysclk = irc_clk */
#define __CORE_CLK (__PLL0_CLK(IRC_OSC) / __CCLK_DIV)
#define __PER_CLK (__PLL0_CLK(IRC_OSC) / __PCLK_DIV)
#define __EMC_CLK (__CORE_CLK / __ECLK_DIV)
#else /* sysclk = osc_clk */
#define __CORE_CLK (__PLL0_CLK(OSC_CLK) / __CCLK_DIV)
#define __PER_CLK (__PLL0_CLK(OSC_CLK) / __PCLK_DIV)
#define __EMC_CLK (__CORE_CLK / __ECLK_DIV)
#endif
#endif
/**
* @}
*/
#else
#define __CORE_CLK (IRC_OSC)
#define __PER_CLK (IRC_OSC)
#define __EMC_CLK (__CORE_CLK)
#endif
/** @addtogroup LPC177x_8x_System_Public_Variables LPC177x_8x System Public Variables
@{
*/
/*----------------------------------------------------------------------------
Clock Variable definitions
*----------------------------------------------------------------------------*/
uint32_t SystemCoreClock = __CORE_CLK;/*!< System Clock Frequency (Core Clock)*/
uint32_t PeripheralClock = __PER_CLK; /*!< Peripheral Clock Frequency (Pclk) */
uint32_t EMCClock = __EMC_CLK; /*!< EMC Clock Frequency
*/
uint32_t USBClock = (48000000UL);
/*!< USB Clock Frequency - this value will
be updated after call SystemCoreClockUpdate, should be 48MHz*/
/**
* @}
*/
/** @addtogroup LPC177x_8x_System_Public_Functions LPC177x_8x System Public Functions
@{
*/
/*----------------------------------------------------------------------------
Clock functions
*----------------------------------------------------------------------------*/
void SystemCoreClockUpdate (void) /* Get Core Clock Frequency */
{
/* Determine clock frequency according to clock register values */
if ((LPC_SC->CCLKSEL &0x100) == 0)
{
if ((LPC_SC->CLKSRCSEL & 0x01) == 0) /* sysclk = irc_clk 如果选择内部RC振荡器作为系统时钟和PLL0的时钟源*/
{
SystemCoreClock = __CLK_DIV(IRC_OSC , (LPC_SC->CCLKSEL & 0x1F));//SystemCoreClock=12MHZ IRC_OSC=12000000UL
PeripheralClock = __CLK_DIV(IRC_OSC , (LPC_SC->PCLKSEL & 0x1F));//PeripheralClock=6MHZ
EMCClock = (SystemCoreClock / ((LPC_SC->EMCCLKSEL & 0x01)+1));//EMCClock=12MHZ/(2)=6MHZ
}
else
{ /* sysclk = osc_clk */
if ((LPC_SC->SCS & 0x40) == 0) //主振荡器不稳定 下面的代码不应该被执行
{
SystemCoreClock = 0;/* this should never happen! */
PeripheralClock = 0;
EMCClock = 0;
}
else
{
SystemCoreClock = __CLK_DIV(OSC_CLK , (LPC_SC->CCLKSEL & 0x1F));
PeripheralClock = __CLK_DIV(OSC_CLK , (LPC_SC->PCLKSEL & 0x1F));
EMCClock = (SystemCoreClock / ((LPC_SC->EMCCLKSEL & 0x01)+1));
}
}
}
else //如果是选择主振荡器为系统时钟和PLL0时钟
{ /* cclk = pll_clk */
if ((LPC_SC->PLL0STAT & 0x100) == 0) //PLL0STAT的bit8如果为1的话说明 PLL处于激活状态
{ /* PLL0 not enabled */
SystemCoreClock = 0; /* this should never happen! */
PeripheralClock = 0;
EMCClock = 0;
}
else
{
if ((LPC_SC->CLKSRCSEL & 0x01) == 0)
{ /* sysclk = irc_clk */
uint8_t mul = ((LPC_SC->PLL0STAT & 0x1F) + 1);
uint8_t cpu_div = (LPC_SC->CCLKSEL & 0x1F);
uint8_t per_div = (LPC_SC->PCLKSEL & 0x1F);
uint8_t emc_div = (LPC_SC->EMCCLKSEL & 0x01)+1;
SystemCoreClock = __CLK_DIV(IRC_OSC * mul , cpu_div);
PeripheralClock = __CLK_DIV(IRC_OSC * mul , per_div);
EMCClock = SystemCoreClock / emc_div;
}
else
{ /* sysclk = osc_clk */
if ((LPC_SC->SCS & 0x40) == 0)
{
SystemCoreClock = 0; /* this should never happen! */
PeripheralClock = 0;
EMCClock = 0;
}
else
{
uint8_t mul = ((LPC_SC->PLL0STAT & 0x1F) + 1);
uint8_t cpu_div = (LPC_SC->CCLKSEL & 0x1F);
uint8_t per_div = (LPC_SC->PCLKSEL & 0x1F);
uint8_t emc_div = (LPC_SC->EMCCLKSEL & 0x01)+1;
SystemCoreClock = __CLK_DIV(OSC_CLK * mul , cpu_div);
PeripheralClock = __CLK_DIV(OSC_CLK * mul , per_div);
EMCClock = SystemCoreClock / emc_div;
}
}
}
}
/* ---update USBClock------------------*/
if(LPC_SC->USBCLKSEL & (0x01<<8))//Use PLL0 as the input to the USB clock divider
{
switch (LPC_SC->USBCLKSEL & 0x1F)
{
case 0:
USBClock = 0; //no clock will be provided to the USB subsystem
break;
case 4:
case 6:
{
uint8_t mul = ((LPC_SC->PLL0STAT & 0x1F) + 1);
uint8_t usb_div = (LPC_SC->USBCLKSEL & 0x1F);
if(LPC_SC->CLKSRCSEL & 0x01)
//pll_clk_in = main_osc
USBClock = OSC_CLK * mul / usb_div;
else //pll_clk_in = irc_clk
USBClock = IRC_OSC * mul / usb_div;
}
break;
default:
USBClock = 0; /* this should never happen! */
}
}
else if(LPC_SC->USBCLKSEL & (0x02<<8))//usb_input_clk = alt_pll (pll1)
{
if(LPC_SC->CLKSRCSEL & 0x01)
//pll1_clk_in = main_osc
USBClock = (OSC_CLK * ((LPC_SC->PLL1STAT & 0x1F) + 1));
else //pll1_clk_in = irc_clk
USBClock = (IRC_OSC * ((LPC_SC->PLL0STAT & 0x1F) + 1));
}
else
USBClock = 0; /* this should never happen! */
}
/* Determine clock frequency according to clock register values */
/**
* Initialize the system
*
* @param none
* @return none
*
* @brief Setup the microcontroller system.
* Initialize the System.
*/
void SystemInit (void)
{
#if (CLOCK_SETUP)/* Clock Setup CLOCK_SETUP定义过所以下面的代码会执行 */
LPC_SC->SCS = SCS_Val;//SCS_Val=0x00000021---->0010 0001
if (SCS_Val & (1 << 5)) { /* 如果晶振使能(XTAL1和XTAL2之间有石英晶体) */
while ((LPC_SC->SCS & (1<<6)) == 0);/* 等待晶振就绪*/
}
LPC_SC->CLKSRCSEL = CLKSRCSEL_Val;/*选择晶振的时钟作为sysclk & PLL0的时钟源 //CLKSRCSEL_Val=0x00000001*/
#if (PLL0_SETUP) //PLL0_SETUP已经定义
LPC_SC->PLL0CFG = PLL0CFG_Val;//PLL0CFG_Val=0x00000009 PLL_OUT_CLK=9*晶振频率
LPC_SC->PLL0CON = 0x01; /* PLL0 使能 其余31bit是预留状态 */
LPC_SC->PLL0FEED = 0xAA;//依次写入0XAA 0X55让PLL起作用
LPC_SC->PLL0FEED = 0x55;
while (!(LPC_SC->PLL0STAT & (1<<10)));/* Wait for PLOCK0 当PLL0STAT的Bit10是1的时候 PLL到达指定的频率*/
#endif
#if (PLL1_SETUP) //PLL1_SETUP已经定义
LPC_SC->PLL1CFG = PLL1CFG_Val;//PLL1CFG_Val=0x23 Alt_PLL_CLK=3MHZ 类似 同上
LPC_SC->PLL1CON = 0x01;/* PLL1 Enable */
LPC_SC->PLL1FEED = 0xAA;
LPC_SC->PLL1FEED = 0x55;
while (!(LPC_SC->PLL1STAT & (1<<10)));/* Wait for PLOCK1 */
#endif
//CCLKSEL_Val=0x00000101 主PLL(PLL0)输出作为CPU时钟分频器的输入 分频系数为1 也就是说 PLL_OUT_CLK就是CPU的时钟
LPC_SC->CCLKSEL = CCLKSEL_Val; /* Setup Clock Divider CCLKSEL_Val=0x00000101 */
//USBCLKSEL_Val=0x00000201 Alt PLL输出作为USB时钟输入 Alt PLL 1分频后给USB
LPC_SC->USBCLKSEL = USBCLKSEL_Val; /* Setup USB Clock Divider */
//EMCCLKSEL_Val=0x00000001 EMC的时钟是CPU时钟的一半
LPC_SC->EMCCLKSEL = EMCCLKSEL_Val; /* EMC Clock Selection */
//PCLKSEL_Val=0x00000002 输入时钟经过2分频给APB外设时钟
LPC_SC->PCLKSEL = PCLKSEL_Val; /* Peripheral Clock Selection */
//PCONP_Val=0x042887DE 外设时钟是下面的这些开启
//0000 0100 0010 1000 1000 0111 1101 1110
// IIC SSP0 IIC1 GPIO PCSSP1 +PCRTC+PCUART4 PCIIC0+PCPWM1+PCUART1 PCUART0+PCTIM1+PCTIM0
LPC_SC->PCONP = PCONP_Val; /* Power Control for Peripherals */
//CLKOUTCFG_Val=0x00000100 允许切换CLKOUT时钟源不受干扰
LPC_SC->CLKOUTCFG = CLKOUTCFG_Val; /* Clock Output Configuration */
#endif
LPC_SC->PBOOST |= 0x03;/* Power Boost control 为3的时候操作允许高达120MHZ频率
为0的时候必须在100MHZ以下*/
#if (FLASH_SETUP == 1)/* Flash Accelerator Setup FLASH_SETUP定义过了*/
//FLASHCFG_Val=0x00005000 FLASHCFG=0x0000503A
// 0101 0000 0011 1010 FLASH访问使用6个CPU时钟
LPC_SC->FLASHCFG = FLASHCFG_Val|0x03A;
#endif
#ifdef __RAM_MODE__ //没有定义__RAM_MODE__ 不是RAM_MODE
SCB->VTOR = 0x10000000 & 0x3FFFFF80;
#else
//中断向量表的位置
SCB->VTOR = 0x00000000 & 0x3FFFFF80;
#endif
SystemCoreClockUpdate();
}
/**
* @}
*/
/**
* @}
*/
* $Id$ system_LPC177x_8x.c
2011-06-02
*//**
* @file system_LPC177x_8x.c
* @brief CMSIS Cortex-M3 Device Peripheral Access Layer Source File
* for the NXP LPC177x_8x Device Series
*
* ARM Limited (ARM) is supplying this software for use with
* Cortex-M processor based microcontrollers. This file can be
* freely distributed within development tools that are supporting
* such ARM based processors.
*
* @version 1.0
* @date 02. June. 2011
* @author NXP MCU SW Application Team
*
* Copyright(C) 2011, NXP Semiconductor
* All rights reserved.
*
***********************************************************************
* Software that is described herein is for illustrative purposes only
* which provides customers with programming information regarding the
* products. This software is supplied "AS IS" without any warranties.
* NXP Semiconductors assumes no responsibility or liability for the
* use of the software, conveys no license or title under any patent,
* copyright, or mask work right to the product. NXP Semiconductors
* reserves the right to make changes in the software without
* notification. NXP Semiconductors also make no representation or
* warranty that such application will be suitable for the specified
* use without further testing or modification.
* Permission to use, copy, modify, and distribute this software and its
* documentation is hereby granted, under NXP Semiconductors'
* relevant copyright in the software, without fee, provided that it
* is used in conjunction with NXP Semiconductors microcontrollers. This
* copyright, permission, and disclaimer notice must appear in all copies of
* this code.
**********************************************************************/
#include <stdint.h>
#include "LPC177x_8x.h"
#include "system_LPC177x_8x.h"
/** @addtogroup LPC177x_8x_System
* @{
*/
#define __CLK_DIV(x,y) (((y) == 0) ? 0: (x)/(y))
/*
//-------- <<< Use Configuration Wizard in Context Menu >>> ------------------
*/
/*--------------------- Clock Configuration ----------------------------------
//
// <e>
Clock Configuration
// <h>
System Controls and Status Register (SCS - address 0x400F C1A0)
// <o1.0>
EMC Shift Control Bit
// <i>
Controls how addresses are output on the EMC address pins for static memories
// <0=>
Static CS addresses match bus width; AD[1] = 0 for 32 bit, AD[0] = 0 for 16+32 bit (Bit 0 is 0)
// <1=>
Static CS addresses start at LSB 0 regardless of memory width (Bit 0 is 1)
//
// <o1.1>
EMC Reset Disable Bit
// <i>
If 0 (zero), all registers and functions of the EMC are initialized upon any reset condition
// <i>
If 1, EMC is still retained its state through a warm reset
// <0=>
Both EMC resets are asserted when any type of chip reset event occurs (Bit 1 is 0)
// <1=>
Portions of EMC will only be reset by POR or BOR event (Bit 1 is 1)
//
// <o1.2>
EMC Burst Control
// <i>
Set to 1 to prevent multiple sequential accesses to memory via EMC static memory chip selects
// <0=>
Burst enabled (Bit 2 is 0)
// <1=>
Bust disbled (Bit 2 is 1)
//
// <o1.3>
MCIPWR Active Level
// <i>
Selects the active level for the SD card interface signal SD_PWR
// <0=>
SD_PWR is active low (inverted output of the SD Card interface block) (Bit 3 is 0)
// <1=>
SD_PWR is active high (follows the output of the SD Card interface block) (Bit 3 is 1)
//
// <o1.4>
Main Oscillator Range Select
// <0=>
In Range 1 MHz to 20 MHz (Bit 4 is 0)
// <1=>
In Range 15 MHz to 25 MHz (Bit 4 is 1)
//
// <o1.5>
Main Oscillator enable
// <i>
0 (zero) means disabled, 1 means enable
//
// <o1.6>
Main Oscillator status (Read-Only)
// </h>
//
// <h>
Clock Source Select Register (CLKSRCSEL - address 0x400F C10C)
// <o2.0>
CLKSRC: Select the clock source for sysclk to PLL0 clock
// <0=>
Internal RC oscillator (Bit 0 is 0)
// <1=>
Main oscillator (Bit 0 is 1)
// </h>
//
// <e3>PLL0 Configuration (Main PLL PLL0CFG - address 0x400F C084)
// <i>
F_in is in the range of 1 MHz to 25 MHz
// <i>
F_cco = (F_in * M * 2 * P) is in range of 156 MHz to 320 MHz
// <i>
PLL out clock = (F_cco / (2 * P)) is in rane of 9.75 MHz to 160 MHz
//
// <o4.0..4> MSEL: PLL Multiplier Value
// <i>
M Value
// <1-32><#-1>
//
// <o4.5..6>
PSEL: PLL Divider Value
// <i>
P Value
// <0=> 1
// <1=>
2
// <2=>
4
// <3=>
8
// </e>
//
// <e5>PLL1 Configuration (Alt PLL PLL1CFG - address 0x400F C0A4)
// <i>
F_in is in the range of 1 MHz to 25 MHz
// <i>
F_cco = (F_in * M * 2 * P) is in range of 156 MHz to 320 MHz
// <i>
PLL out clock = (F_cco / (2 * P)) is in rane of 9.75 MHz to 160 MHz
//
// <o6.0..4> MSEL: PLL Multiplier Value
// <i>
M Value
// <1-32><#-1>
//
// <o6.5..6>
PSEL: PLL Divider Value
// <i>
P Value
// <0=>
1
// <1=>
2
// <2=>
4
// <3=>
8
// </e>
//
// <h>
CPU Clock Selection Register (CCLKSEL - address 0x400F C104)
// <o7.0..4>
CCLKDIV: Select the value for divider of CPU clock (CCLK)
// <i>
0: The divider is turned off. No clock will be provided to the CPU
// <i>
n: The input clock is divided by n to produce the CPU clock
// <0-31>
//
// <o7.8>
CCLKSEL: Select the input to the divider of CPU clock
// <0=>
sysclk clock is used
// <1=>
Main PLL0 clock is used
// </h>
//
// <h>
USB Clock Selection Register (USBCLKSEL - 0x400F C108)
// <o8.0..4>
USBDIV: USB clock (source PLL0) divider selection
// <0=>
Divider is off and no clock provides to USB subsystem
// <4=>
Divider value is 4 (The source clock is divided by 4)
// <6=>
Divider value is 6 (The source clock is divided by 6)
//
// <o8.8..9>
USBSEL: Select the source for USB clock divider
// <i>
When CPU clock is selected, the USB can be accessed
// <i>
by software but cannot perform USB functions
// <0=>
sysclk clock (the clock input to PLL0)
// <1=>
The clock output from PLL0
// <2=>
The clock output from PLL1
// </h>
//
// <h>
EMC Clock Selection Register (EMCCLKSEL - address 0x400F C100)
// <o9.0>
EMCDIV: Set the divider for EMC clock
// <0=> Divider value is 1
// <1=> Divider value is 2 (EMC clock is equal a half of input clock)
// </h>
//
// <h>
Peripheral Clock Selection Register (PCLKSEL - address 0x400F C1A8)
// <o10.0..4>
PCLKDIV: APB Peripheral clock divider
// <i>
0: The divider is turned off. No clock will be provided to APB peripherals
// <i>
n: The input clock is divided by n to produce the APB peripheral clock
// <0-31>
// </h>
//
// <h>
Power Control for Peripherals Register (PCONP - address 0x400F C1C8)
// <o11.0>
PCLCD: LCD controller power/clock enable (bit 0)
// <o11.1>
PCTIM0: Timer/Counter 0 power/clock enable (bit 1)
// <o11.2>
PCTIM1: Timer/Counter 1 power/clock enable (bit 2)
// <o11.3>
PCUART0: UART 0 power/clock enable (bit 3)
// <o11.4>
PCUART1: UART 1 power/clock enable (bit 4)
// <o11.5>
PCPWM0: PWM0 power/clock enable (bit 5)
// <o11.6>
PCPWM1: PWM1 power/clock enable (bit 6)
// <o11.7>
PCI2C0: I2C 0 interface power/clock enable (bit 7)
// <o11.8>
PCUART4: UART 4 power/clock enable (bit 8)
// <o11.9>
PCRTC: RTC and Event Recorder power/clock enable (bit 9)
// <o11.10>
PCSSP1: SSP 1 interface power/clock enable (bit 10)
// <o11.11>
PCEMC: External Memory Controller power/clock enable (bit 11)
// <o11.12>
PCADC: A/D converter power/clock enable (bit 12)
// <o11.13>
PCCAN1: CAN controller 1 power/clock enable (bit 13)
// <o11.14>
PCCAN2: CAN controller 2 power/clock enable (bit 14)
// <o11.15>
PCGPIO: IOCON, GPIO, and GPIO interrupts power/clock enable (bit 15)
// <o11.17>
PCMCPWM: Motor Control PWM power/clock enable (bit 17)
// <o11.18>
PCQEI: Quadrature encoder interface power/clock enable (bit 18)
// <o11.19>
PCI2C1: I2C 1 interface power/clock enable (bit 19)
// <o11.20>
PCSSP2: SSP 2 interface power/clock enable (bit 20)
// <o11.21>
PCSSP0: SSP 0 interface power/clock enable (bit 21)
// <o11.22>
PCTIM2: Timer 2 power/clock enable (bit 22)
// <o11.23>
PCTIM3: Timer 3 power/clock enable (bit 23)
// <o11.24>
PCUART2: UART 2 power/clock enable (bit 24)
// <o11.25>
PCUART3: UART 3 power/clock enable (bit 25)
// <o11.26>
PCI2C2: I2C 2 interface power/clock enable (bit 26)
// <o11.27>
PCI2S: I2S interface power/clock enable (bit 27)
// <o11.28>
PCSDC: SD Card interface power/clock enable (bit 28)
// <o11.29>
PCGPDMA: GPDMA function power/clock enable (bit 29)
// <o11.30>
PCENET: Ethernet block power/clock enable (bit 30)
// <o11.31>
PCUSB: USB interface power/clock enable (bit 31)
// </h>
//
// <h>
Clock Output Configuration Register (CLKOUTCFG)
// <o12.0..3>
CLKOUTSEL: Clock Source for CLKOUT Selection
// <0=>
CPU clock
// <1=>
Main Oscillator
// <2=>
Internal RC Oscillator
// <3=>
USB clock
// <4=>
RTC Oscillator
// <5=>
unused
// <6=>
Watchdog Oscillator
//
// <o12.4..7>
CLKOUTDIV: Output Clock Divider
// <1-16><#-1>
//
// <o12.8>
CLKOUT_EN: CLKOUT enable
// </h>
//
// </e>
*/
/** @addtogroup LPC177x_8x_System_Defines LPC177x_8x System Defines
@{
*/
#define CLOCK_SETUP 1
#define SCS_Val 0x00000021
#define CLKSRCSEL_Val 0x00000001
#define PLL0_SETUP 1
#define PLL0CFG_Val 0x00000009
#define PLL1_SETUP 1
#define PLL1CFG_Val 0x00000023
#define CCLKSEL_Val 0x00000101
#define USBCLKSEL_Val 0x00000201
#define EMCCLKSEL_Val 0x00000001
#define PCLKSEL_Val 0x00000002
#define PCONP_Val 0x042887DE
#define CLKOUTCFG_Val 0x00000100
/*--------------------- Flash Accelerator Configuration ----------------------
//
// <e>
Flash Accelerator Configuration register (FLASHCFG - address 0x400F C000)
// <o1.12..15>
FLASHTIM: Flash Access Time
// <0=>
1 CPU clock (for CPU clock up to 20 MHz)
// <1=>
2 CPU clocks (for CPU clock up to 40 MHz)
// <2=>
3 CPU clocks (for CPU clock up to 60 MHz)
// <3=>
4 CPU clocks (for CPU clock up to 80 MHz)
// <4=>
5 CPU clocks (for CPU clock up to 100 MHz)
// <5=>
6 CPU clocks (for any CPU clock)
// </e>
*/
#define FLASH_SETUP 1
#define FLASHCFG_Val 0x00005000
/*
//-------- <<< end of configuration section >>> ------------------------------
*/
/*----------------------------------------------------------------------------
Check the register settings
*----------------------------------------------------------------------------*/
#define CHECK_RANGE(val, min, max) ((val < min) || (val > max))
#define CHECK_RSVD(val, mask) (val & mask)
/* Clock Configuration -------------------------------------------------------*/
#if (CHECK_RSVD((SCS_Val), ~0x0000003F))
#error "SCS: Invalid values of reserved bits!"
#endif
#if (CHECK_RANGE((CLKSRCSEL_Val), 0, 1))
#error "CLKSRCSEL: Value out of range!"
#endif
#if (CHECK_RSVD((PLL0CFG_Val), ~0x0000007F))
#error "PLL0CFG: Invalid values of reserved bits!"
#endif
#if (CHECK_RSVD((PLL1CFG_Val), ~0x0000007F))
#error "PLL1CFG: Invalid values of reserved bits!"
#endif
#if (CHECK_RSVD((CCLKSEL_Val), ~0x0000011F))
#error "CCLKSEL: Invalid values of reserved bits!"
#endif
#if (CHECK_RSVD((USBCLKSEL_Val), ~0x0000031F))
#error "USBCLKSEL: Invalid values of reserved bits!"
#endif
#if (CHECK_RSVD((EMCCLKSEL_Val), ~0x00000001))
#error "EMCCLKSEL: Invalid values of reserved bits!"
#endif
#if (CHECK_RSVD((PCLKSEL_Val), ~0x0000001F))
#error "PCLKSEL: Invalid values of reserved bits!"
#endif
#if (CHECK_RSVD((PCONP_Val), ~0xFFFEFFFF))
#error "PCONP: Invalid values of reserved bits!"
#endif
#if (CHECK_RSVD((CLKOUTCFG_Val), ~0x000001FF))
#error "CLKOUTCFG: Invalid values of reserved bits!"
#endif
/* Flash Accelerator Configuration -------------------------------------------*/
#if (CHECK_RSVD((FLASHCFG_Val), ~0x0000F000))
#warning "FLASHCFG: Invalid values of reserved bits!"
#endif
/*----------------------------------------------------------------------------
DEFINES
*----------------------------------------------------------------------------*/
/* pll_out_clk = F_cco / (2 ?P)
F_cco = pll_in_clk ?M ?2 ?P */
#define __M ((PLL0CFG_Val & 0x1F) + 1)
#define __PLL0_CLK(__F_IN) (__F_IN * __M)
#define __CCLK_DIV (CCLKSEL_Val & 0x1F)
#define __PCLK_DIV (PCLKSEL_Val & 0x1F)
#define __ECLK_DIV ((EMCCLKSEL_Val & 0x01) + 1)
/* Determine core clock frequency according to settings */
#if (CLOCK_SETUP) /* Clock Setup */
#if ((CLKSRCSEL_Val & 0x01) == 1) && ((SCS_Val & 0x20)== 0)
#error "Main Oscillator is selected as clock source but is not enabled!"
#endif
#if ((CCLKSEL_Val & 0x100) == 0x100) && (PLL0_SETUP == 0)
#error "Main PLL is selected as clock source but is not enabled!"
#endif
#if ((CCLKSEL_Val & 0x100) == 0) /* cclk = sysclk */
#if ((CLKSRCSEL_Val & 0x01) == 0) /* sysclk = irc_clk */
#define __CORE_CLK (IRC_OSC / __CCLK_DIV)
#define __PER_CLK (IRC_OSC/ __PCLK_DIV)
#define __EMC_CLK (__CORE_CLK/ __ECLK_DIV)
#else /* sysclk = osc_clk */
#define __CORE_CLK (OSC_CLK / __CCLK_DIV)
#define __PER_CLK (OSC_CLK/ __PCLK_DIV)
#define __EMC_CLK (__CORE_CLK/ __ECLK_DIV)
#endif
#else /* cclk = pll_clk */
#if ((CLKSRCSEL_Val & 0x01) == 0) /* sysclk = irc_clk */
#define __CORE_CLK (__PLL0_CLK(IRC_OSC) / __CCLK_DIV)
#define __PER_CLK (__PLL0_CLK(IRC_OSC) / __PCLK_DIV)
#define __EMC_CLK (__CORE_CLK / __ECLK_DIV)
#else /* sysclk = osc_clk */
#define __CORE_CLK (__PLL0_CLK(OSC_CLK) / __CCLK_DIV)
#define __PER_CLK (__PLL0_CLK(OSC_CLK) / __PCLK_DIV)
#define __EMC_CLK (__CORE_CLK / __ECLK_DIV)
#endif
#endif
/**
* @}
*/
#else
#define __CORE_CLK (IRC_OSC)
#define __PER_CLK (IRC_OSC)
#define __EMC_CLK (__CORE_CLK)
#endif
/** @addtogroup LPC177x_8x_System_Public_Variables LPC177x_8x System Public Variables
@{
*/
/*----------------------------------------------------------------------------
Clock Variable definitions
*----------------------------------------------------------------------------*/
uint32_t SystemCoreClock = __CORE_CLK;/*!< System Clock Frequency (Core Clock)*/
uint32_t PeripheralClock = __PER_CLK; /*!< Peripheral Clock Frequency (Pclk) */
uint32_t EMCClock = __EMC_CLK; /*!< EMC Clock Frequency
*/
uint32_t USBClock = (48000000UL);
/*!< USB Clock Frequency - this value will
be updated after call SystemCoreClockUpdate, should be 48MHz*/
/**
* @}
*/
/** @addtogroup LPC177x_8x_System_Public_Functions LPC177x_8x System Public Functions
@{
*/
/*----------------------------------------------------------------------------
Clock functions
*----------------------------------------------------------------------------*/
void SystemCoreClockUpdate (void) /* Get Core Clock Frequency */
{
/* Determine clock frequency according to clock register values */
if ((LPC_SC->CCLKSEL &0x100) == 0)
{
if ((LPC_SC->CLKSRCSEL & 0x01) == 0) /* sysclk = irc_clk 如果选择内部RC振荡器作为系统时钟和PLL0的时钟源*/
{
SystemCoreClock = __CLK_DIV(IRC_OSC , (LPC_SC->CCLKSEL & 0x1F));//SystemCoreClock=12MHZ IRC_OSC=12000000UL
PeripheralClock = __CLK_DIV(IRC_OSC , (LPC_SC->PCLKSEL & 0x1F));//PeripheralClock=6MHZ
EMCClock = (SystemCoreClock / ((LPC_SC->EMCCLKSEL & 0x01)+1));//EMCClock=12MHZ/(2)=6MHZ
}
else
{ /* sysclk = osc_clk */
if ((LPC_SC->SCS & 0x40) == 0) //主振荡器不稳定 下面的代码不应该被执行
{
SystemCoreClock = 0;/* this should never happen! */
PeripheralClock = 0;
EMCClock = 0;
}
else
{
SystemCoreClock = __CLK_DIV(OSC_CLK , (LPC_SC->CCLKSEL & 0x1F));
PeripheralClock = __CLK_DIV(OSC_CLK , (LPC_SC->PCLKSEL & 0x1F));
EMCClock = (SystemCoreClock / ((LPC_SC->EMCCLKSEL & 0x01)+1));
}
}
}
else //如果是选择主振荡器为系统时钟和PLL0时钟
{ /* cclk = pll_clk */
if ((LPC_SC->PLL0STAT & 0x100) == 0) //PLL0STAT的bit8如果为1的话说明 PLL处于激活状态
{ /* PLL0 not enabled */
SystemCoreClock = 0; /* this should never happen! */
PeripheralClock = 0;
EMCClock = 0;
}
else
{
if ((LPC_SC->CLKSRCSEL & 0x01) == 0)
{ /* sysclk = irc_clk */
uint8_t mul = ((LPC_SC->PLL0STAT & 0x1F) + 1);
uint8_t cpu_div = (LPC_SC->CCLKSEL & 0x1F);
uint8_t per_div = (LPC_SC->PCLKSEL & 0x1F);
uint8_t emc_div = (LPC_SC->EMCCLKSEL & 0x01)+1;
SystemCoreClock = __CLK_DIV(IRC_OSC * mul , cpu_div);
PeripheralClock = __CLK_DIV(IRC_OSC * mul , per_div);
EMCClock = SystemCoreClock / emc_div;
}
else
{ /* sysclk = osc_clk */
if ((LPC_SC->SCS & 0x40) == 0)
{
SystemCoreClock = 0; /* this should never happen! */
PeripheralClock = 0;
EMCClock = 0;
}
else
{
uint8_t mul = ((LPC_SC->PLL0STAT & 0x1F) + 1);
uint8_t cpu_div = (LPC_SC->CCLKSEL & 0x1F);
uint8_t per_div = (LPC_SC->PCLKSEL & 0x1F);
uint8_t emc_div = (LPC_SC->EMCCLKSEL & 0x01)+1;
SystemCoreClock = __CLK_DIV(OSC_CLK * mul , cpu_div);
PeripheralClock = __CLK_DIV(OSC_CLK * mul , per_div);
EMCClock = SystemCoreClock / emc_div;
}
}
}
}
/* ---update USBClock------------------*/
if(LPC_SC->USBCLKSEL & (0x01<<8))//Use PLL0 as the input to the USB clock divider
{
switch (LPC_SC->USBCLKSEL & 0x1F)
{
case 0:
USBClock = 0; //no clock will be provided to the USB subsystem
break;
case 4:
case 6:
{
uint8_t mul = ((LPC_SC->PLL0STAT & 0x1F) + 1);
uint8_t usb_div = (LPC_SC->USBCLKSEL & 0x1F);
if(LPC_SC->CLKSRCSEL & 0x01)
//pll_clk_in = main_osc
USBClock = OSC_CLK * mul / usb_div;
else //pll_clk_in = irc_clk
USBClock = IRC_OSC * mul / usb_div;
}
break;
default:
USBClock = 0; /* this should never happen! */
}
}
else if(LPC_SC->USBCLKSEL & (0x02<<8))//usb_input_clk = alt_pll (pll1)
{
if(LPC_SC->CLKSRCSEL & 0x01)
//pll1_clk_in = main_osc
USBClock = (OSC_CLK * ((LPC_SC->PLL1STAT & 0x1F) + 1));
else //pll1_clk_in = irc_clk
USBClock = (IRC_OSC * ((LPC_SC->PLL0STAT & 0x1F) + 1));
}
else
USBClock = 0; /* this should never happen! */
}
/* Determine clock frequency according to clock register values */
/**
* Initialize the system
*
* @param none
* @return none
*
* @brief Setup the microcontroller system.
* Initialize the System.
*/
void SystemInit (void)
{
#if (CLOCK_SETUP)/* Clock Setup CLOCK_SETUP定义过所以下面的代码会执行 */
LPC_SC->SCS = SCS_Val;//SCS_Val=0x00000021---->0010 0001
if (SCS_Val & (1 << 5)) { /* 如果晶振使能(XTAL1和XTAL2之间有石英晶体) */
while ((LPC_SC->SCS & (1<<6)) == 0);/* 等待晶振就绪*/
}
LPC_SC->CLKSRCSEL = CLKSRCSEL_Val;/*选择晶振的时钟作为sysclk & PLL0的时钟源 //CLKSRCSEL_Val=0x00000001*/
#if (PLL0_SETUP) //PLL0_SETUP已经定义
LPC_SC->PLL0CFG = PLL0CFG_Val;//PLL0CFG_Val=0x00000009 PLL_OUT_CLK=9*晶振频率
LPC_SC->PLL0CON = 0x01; /* PLL0 使能 其余31bit是预留状态 */
LPC_SC->PLL0FEED = 0xAA;//依次写入0XAA 0X55让PLL起作用
LPC_SC->PLL0FEED = 0x55;
while (!(LPC_SC->PLL0STAT & (1<<10)));/* Wait for PLOCK0 当PLL0STAT的Bit10是1的时候 PLL到达指定的频率*/
#endif
#if (PLL1_SETUP) //PLL1_SETUP已经定义
LPC_SC->PLL1CFG = PLL1CFG_Val;//PLL1CFG_Val=0x23 Alt_PLL_CLK=3MHZ 类似 同上
LPC_SC->PLL1CON = 0x01;/* PLL1 Enable */
LPC_SC->PLL1FEED = 0xAA;
LPC_SC->PLL1FEED = 0x55;
while (!(LPC_SC->PLL1STAT & (1<<10)));/* Wait for PLOCK1 */
#endif
//CCLKSEL_Val=0x00000101 主PLL(PLL0)输出作为CPU时钟分频器的输入 分频系数为1 也就是说 PLL_OUT_CLK就是CPU的时钟
LPC_SC->CCLKSEL = CCLKSEL_Val; /* Setup Clock Divider CCLKSEL_Val=0x00000101 */
//USBCLKSEL_Val=0x00000201 Alt PLL输出作为USB时钟输入 Alt PLL 1分频后给USB
LPC_SC->USBCLKSEL = USBCLKSEL_Val; /* Setup USB Clock Divider */
//EMCCLKSEL_Val=0x00000001 EMC的时钟是CPU时钟的一半
LPC_SC->EMCCLKSEL = EMCCLKSEL_Val; /* EMC Clock Selection */
//PCLKSEL_Val=0x00000002 输入时钟经过2分频给APB外设时钟
LPC_SC->PCLKSEL = PCLKSEL_Val; /* Peripheral Clock Selection */
//PCONP_Val=0x042887DE 外设时钟是下面的这些开启
//0000 0100 0010 1000 1000 0111 1101 1110
// IIC SSP0 IIC1 GPIO PCSSP1 +PCRTC+PCUART4 PCIIC0+PCPWM1+PCUART1 PCUART0+PCTIM1+PCTIM0
LPC_SC->PCONP = PCONP_Val; /* Power Control for Peripherals */
//CLKOUTCFG_Val=0x00000100 允许切换CLKOUT时钟源不受干扰
LPC_SC->CLKOUTCFG = CLKOUTCFG_Val; /* Clock Output Configuration */
#endif
LPC_SC->PBOOST |= 0x03;/* Power Boost control 为3的时候操作允许高达120MHZ频率
为0的时候必须在100MHZ以下*/
#if (FLASH_SETUP == 1)/* Flash Accelerator Setup FLASH_SETUP定义过了*/
//FLASHCFG_Val=0x00005000 FLASHCFG=0x0000503A
// 0101 0000 0011 1010 FLASH访问使用6个CPU时钟
LPC_SC->FLASHCFG = FLASHCFG_Val|0x03A;
#endif
#ifdef __RAM_MODE__ //没有定义__RAM_MODE__ 不是RAM_MODE
SCB->VTOR = 0x10000000 & 0x3FFFFF80;
#else
//中断向量表的位置
SCB->VTOR = 0x00000000 & 0x3FFFFF80;
#endif
SystemCoreClockUpdate();
}
/**
* @}
*/
/**
* @}
*/
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