RIOT/board/olimex_lpc2148/board_init.c

/*
 * bl_board_init.c
 *
 *  Created on: 19.08.2008
 *      Author: heiko, kaspar
 */

#include "cpu.h"
#include "bits.h"
#include "VIC.h"

#define PLOCK 0x400

static void feed(void)
{
	PLL0FEED = 0xAA;
	PLL0FEED = 0x55;
}

void bl_init_clks(void)
{

	// 				Setting the Phased Lock Loop (PLL)
	//               ----------------------------------
	//
	// Olimex LPC-P2148 has a 12.0000 mhz crystal
	//
	// We'd like the LPC2148 to run at 60 mhz (has to be an even multiple of crystal)
	//
	// According to the Philips LPC2148 manual:   M = cclk / Fosc	where:	M    = PLL multiplier (bits 0-4 of PLLCFG)
	//																		cclk = 60000000 hz
	//																		Fosc = 12000000 hz
	//
	// Solving:	M = 60000000 / 12000000 = 5
	//
	//			Note: M - 1 must be entered into bits 0-4 of PLLCFG (assign 4 to these bits)
	//
	//
	// The Current Controlled Oscilator (CCO) must operate in the range 156 mhz to 320 mhz
	//
	// According to the Philips LPC2148 manual:	Fcco = cclk * 2 * P    where:	Fcco = CCO frequency
	//																			cclk = 60000000 hz
	//																			P = PLL divisor (bits 5-6 of PLLCFG)
	//
	// Solving:	Fcco = 60000000 * 2 * P
	//			P = 2  (trial value)
	//			Fcco = 60000000 * 2 * 2
	//			Fcc0 = 240000000 hz    (good choice for P since it's within the 156 mhz to 320 mhz range)
	//
	// From Table 22 (page 34) of Philips LPC2148 manual    P = 2, PLLCFG bits 5-6 = 1  (assign 1 to these bits)
	//
	// Finally:      PLLCFG = 0  01  00100  =  0x24
	//
	// Final note: to load PLLCFG register, we must use the 0xAA followed 0x55 write sequence to the PLLFEED register
	//             this is done in the short function feed() below
	//

	// Setting Multiplier and Divider values
  	PLL0CFG = 0x24;
  	feed();

	// Enabling the PLL */
	PLL0CON = 0x1;
	feed();

	// Wait for the PLL to lock to set frequency
	while(!(PLL0STAT & PLOCK)) ;

	// Connect the PLL as the clock source
	PLL0CON = 0x3;
	feed();

	// Enabling MAM and setting number of clocks used for Flash memory fetch
	MAMTIM = 0x3;
	MAMCR = 0x2;

	// Setting peripheral Clock (pclk) to 1/2 System Clock (cclk)
	VPBDIV = PCLK_DIV;
}




void bl_init_ports(void)
{

}