www.pudn.com > 8051_pppsrc.zip > pll.c, change:2001-02-09,size:1140b

/*///////////////////////////////////////////////////////////////////////////// 
 
File Name : Pll.c 
 
Author : Rene Trenado 
 
Location : Motorola Applications Lab, Baja California 
 
Date Created : September 2000 
 
Current Revision : 0.0 
 
Notes : This file contains the code of the InitPll function 
 
//////////////////////////////////////////////////////////////////////////////*/ 
 
#include "pll.h" 
 
 
 
/*********************************************************************** 
Function : 	InitPll 
 
Parameters : 	None 
 
Date : 		September 2000 
 
Desc : 		Initializes the PLL to operate at 4.91520 MHz 
 
***********************************************************************/ 
#asm 
	xdef	_InitPLL 
 
_InitPLL: 
	BCLR    5,0x36              	;turn off PLL so it can be initialized 
	MOV		  #0x00,0x38	;Set multiplier for 4.9152MHz 
  	MOV		  #0x96,0x39	;see manual for calculations 
	MOV		  #0x80,0x3A	;Set range select 
  	BSET    7,0x37			;Allow automatic acquisition & tracking 
	BSET    5,0x36			;turn PLL back on 
HERE: 
  	BRCLR	  6,0x37,HERE		;Wait for PLL to lock 
	BSET	  4,0x36		;Select PLL as Source 
 
#endasm