cpu.c
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/*
* Copyright (C) 2015 Freie Universität Berlin
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @ingroup cpu_lpc11u34
* @{
*
* @file
* @brief Implementation of the CPU initialization
*
* @author Paul RATHGEB <paul.rathgeb@skynet.be>
* @}
*/
#include "cpu.h"
#define SYSOSCCTRL_Val 0x00000000 /* Reset: 0x000 */
#define SYSPLLCTRL_Val 0x00000023 /* Reset: 0x000 */
#define SYSPLLCLKSEL_Val 0x00000001 /* Reset: 0x000 */
#define MAINCLKSEL_Val 0x00000003 /* Reset: 0x000 */
#define SYSAHBCLKDIV_Val 0x00000001 /* Reset: 0x001 */
#define USBPLLCTRL_Val 0x00000023 /* Reset: 0x000 */
#define USBPLLCLKSEL_Val 0x00000001 /* Reset: 0x000 */
#define USBCLKSEL_Val 0x00000000 /* Reset: 0x000 */
#define USBCLKDIV_Val 0x00000001 /* Reset: 0x001 */
/**
* @brief Initialize the CPU clock
*
* This configuration use an external XTAL
*/
void clk_init(void)
{
volatile uint32_t i;
/* Power-up System Osc */
LPC_SYSCON->PDRUNCFG &= ~(1 << 5);
LPC_SYSCON->SYSOSCCTRL = SYSOSCCTRL_Val;
for (i = 0; i < 200; i++) __NOP();
/* Select PLL Input*/
LPC_SYSCON->SYSPLLCLKSEL = SYSPLLCLKSEL_Val;
/* Update clock source */
LPC_SYSCON->SYSPLLCLKUEN = 0x01;
/* Toggle update register */
LPC_SYSCON->SYSPLLCLKUEN = 0x00;
LPC_SYSCON->SYSPLLCLKUEN = 0x01;
/* Wait until updated */
while (!(LPC_SYSCON->SYSPLLCLKUEN & 0x01));
/* Main Clock is PLL Out */
LPC_SYSCON->SYSPLLCTRL = SYSPLLCTRL_Val;
/* Power-up SYSPLL */
LPC_SYSCON->PDRUNCFG &= ~(1 << 7);
/* Wait Until PLL Locked */
while (!(LPC_SYSCON->SYSPLLSTAT & 0x01));
/* Select PLL Clock Output */
LPC_SYSCON->MAINCLKSEL = MAINCLKSEL_Val;
/* Update MCLK Clock Source */
LPC_SYSCON->MAINCLKUEN = 0x01;
/* Toggle Update Register */
LPC_SYSCON->MAINCLKUEN = 0x00;
LPC_SYSCON->MAINCLKUEN = 0x01;
/* Wait Until Updated */
while (!(LPC_SYSCON->MAINCLKUEN & 0x01));
LPC_SYSCON->SYSAHBCLKDIV = SYSAHBCLKDIV_Val;
/* Power-up USB PHY */
LPC_SYSCON->PDRUNCFG &= ~(1 << 10);
/* Power-up USB PLL */
LPC_SYSCON->PDRUNCFG &= ~(1 << 8);
/* Select PLL Input */
LPC_SYSCON->USBPLLCLKSEL = USBPLLCLKSEL_Val;
/* Update Clock Source */
LPC_SYSCON->USBPLLCLKUEN = 0x01;
/* Toggle Update Register */
LPC_SYSCON->USBPLLCLKUEN = 0x00;
LPC_SYSCON->USBPLLCLKUEN = 0x01;
/* Wait Until Updated */
while (!(LPC_SYSCON->USBPLLCLKUEN & 0x01));
LPC_SYSCON->USBPLLCTRL = USBPLLCTRL_Val;
/* Wait Until PLL Locked */
while (!(LPC_SYSCON->USBPLLSTAT & 0x01));
/* Select USB Clock */
LPC_SYSCON->USBCLKSEL = USBCLKSEL_Val;
/* Toggle Update Register */
LPC_SYSCON->USBCLKUEN = 0x00;
LPC_SYSCON->USBCLKUEN = 0x01;
/* Set USB clock divider */
LPC_SYSCON->USBCLKDIV = USBCLKDIV_Val;
/* System clock to the IOCON needs to be enabled or
most of the I/O related peripherals won't work. */
LPC_SYSCON->SYSAHBCLKCTRL |= (1<<16);
}
/**
* @brief Initialize the CPU, set IRQ priorities
*/
void cpu_init(void)
{
/* initialize the Cortex-M core */
cortexm_init();
/* initialize the clock */
clk_init();
}