//-----------------------------------------------------------------------------
// F12x_INIT_2.c
//-----------------------------------------------------------------------------
// Copyright 2002 Cygnal Integrated Products, Inc.
//
// AUTH: FB
// DATE: 19 SEP 02
//
// This file contains example initialization routines for the C8051F12x series
// of devices. 
//
// This program uses a 22.1184 Mhz crystal oscillator multiplied by (9/4) 
// for an effective SYSCLK of 49.7664 Mhz. This program also initializes and 
// uses UART0 at <BAUDRATE> bits per second. 
//
//
// Target: C8051F12x
// Tool chain: KEIL C51 6.03 / KEIL EVAL C51
//

//-----------------------------------------------------------------------------
// Includes
//-----------------------------------------------------------------------------
#include <c8051f120.h>                 // SFR declarations
#include <stdio.h>                     // printf() and getchar()

//-----------------------------------------------------------------------------
// 16-bit SFR Definitions for 'F12x
//-----------------------------------------------------------------------------

sfr16 DP       = 0x82;                 // data pointer
sfr16 ADC0     = 0xbe;                 // ADC0 data
sfr16 ADC0GT   = 0xc4;                 // ADC0 greater than window
sfr16 ADC0LT   = 0xc6;                 // ADC0 less than window
sfr16 RCAP2    = 0xca;                 // Timer2 capture/reload
sfr16 RCAP3    = 0xca;                 // Timer3 capture/reload
sfr16 RCAP4    = 0xca;                 // Timer4 capture/reload
sfr16 TMR2     = 0xcc;                 // Timer2
sfr16 TMR3     = 0xcc;                 // Timer3
sfr16 TMR4     = 0xcc;                 // Timer4
sfr16 DAC0     = 0xd2;                 // DAC0 data
sfr16 DAC1     = 0xd2;                 // DAC1 data
sfr16 PCA0CP5  = 0xe1;                 // PCA0 Module 5 capture
sfr16 PCA0CP2  = 0xe9;                 // PCA0 Module 2 capture
sfr16 PCA0CP3  = 0xeb;                 // PCA0 Module 3 capture
sfr16 PCA0CP4  = 0xed;                 // PCA0 Module 4 capture
sfr16 PCA0     = 0xf9;                 // PCA0 counter
sfr16 PCA0CP0  = 0xfb;                 // PCA0 Module 0 capture
sfr16 PCA0CP1  = 0xfd;                 // PCA0 Module 1 capture

//-----------------------------------------------------------------------------
// Global CONSTANTS
//-----------------------------------------------------------------------------
#define TRUE         1
#define FALSE        0

#define EXTCLK       22118400          // External oscillator frequency in Hz
#define SYSCLK       49760000          // Output of PLL derived from 
                                       // (EXTCLK*9/4)

#define BAUDRATE     115200            // Baud rate of UART in bps
                                       // Note: The minimum standard baud rate
                                       // supported by the UART0_Init routine
                                       // in this file is 19,200 bps when
                                       // SYSCLK = 49.76MHz. 

sbit LED = P1^6;                       // LED='1' means ON
sbit SW2 = P3^7;                       // SW2='0' means switch pressed


//-----------------------------------------------------------------------------
// Function PROTOTYPES
//-----------------------------------------------------------------------------
void main(void);
void SYSCLK_Init(void);
void PORT_Init(void);
void UART0_Init (void);

//-----------------------------------------------------------------------------
// MAIN Routine
//-----------------------------------------------------------------------------

void main (void) 
{

   WDTCN = 0xde;                       // disable watchdog timer
   WDTCN = 0xad;

   PORT_Init ();                       // initialize crossbar and GPIO
   SYSCLK_Init ();                     // initialize oscillator
   UART0_Init ();                      // initialize UART0
   

   SFRPAGE = UART0_PAGE;               // Direct printf output to UART0
   printf("Hello\n");                  // Print a string

   while(1);

} 

//-----------------------------------------------------------------------------
// Initialization Routines
//-----------------------------------------------------------------------------

//-----------------------------------------------------------------------------
// SYSCLK_Init
//-----------------------------------------------------------------------------
//
// This routine initializes the system clock to use an external 22.1184 MHz 
// crystal oscillator multiplied by a factor of 9/4 using the PLL as its 
// clock source. The resulting frequency is 22.1184 MHz * 9/4 = 49.7664 MHz
//
void SYSCLK_Init (void)
{
   int i;                           // delay counter
   
   char SFRPAGE_SAVE = SFRPAGE;     // Save Current SFR page

   SFRPAGE = CONFIG_PAGE;           // set SFR page

   OSCXCN = 0x67;                   // start external oscillator with
                                    // 22.1184MHz crystal

   for (i=0; i < 256; i++) ;        // Wait for osc. to start up
   
   while (!(OSCXCN & 0x80)) ;       // Wait for crystal osc. to settle

   CLKSEL = 0x01;                   // Select the external osc. as
                                    // the SYSCLK source

   OSCICN = 0x00;                   // Disable the internal osc.
   
   //Turn on the PLL and increase the system clock by a factor of M/N = 9/4
   SFRPAGE = CONFIG_PAGE;
   
   PLL0CN  = 0x04;                  // Set PLL source as external osc.
   SFRPAGE = LEGACY_PAGE;
   FLSCL   = 0x10;                  // Set FLASH read time for 50MHz clk 
                                    // or less 
   SFRPAGE = CONFIG_PAGE;
   PLL0CN |= 0x01;                  // Enable Power to PLL
   PLL0DIV = 0x04;                  // Set Pre-divide value to N (N = 4)
   PLL0FLT = 0x01;                  // Set the PLL filter register for 
                                    // a reference clock from 19 - 30 MHz
                                    // and an output clock from 45 - 80 MHz 
   PLL0MUL = 0x09;                  // Multiply SYSCLK by M (M = 9)
   
   for (i=0; i < 256; i++) ;        // Wait at least 5us
   PLL0CN  |= 0x02;                 // Enable the PLL
   while(!(PLL0CN & 0x10));         // Wait until PLL frequency is locked
   CLKSEL  = 0x02;                  // Select PLL as SYSCLK source

   SFRPAGE = SFRPAGE_SAVE;          // Restore SFR page
}


//-----------------------------------------------------------------------------
// PORT_Init
//-----------------------------------------------------------------------------
//
// This routine configures the crossbar and GPIO ports.
//
void PORT_Init (void)
{
   char SFRPAGE_SAVE = SFRPAGE;     // Save Current SFR page
      
   SFRPAGE = CONFIG_PAGE;           // set SFR page

   XBR0     = 0x04;                 // Enable UART0
   XBR1     = 0x00;
   XBR2     = 0x40;                 // Enable crossbar and weak pull-up
                                    

   P0MDOUT |= 0x01;                 // Set TX0 pin to push-pull
   P1MDOUT |= 0x40;                 // Set P1.6(LED) to push-pull
   
   SFRPAGE = SFRPAGE_SAVE;          // Restore SFR page
}

//-----------------------------------------------------------------------------
// UART0_Init
//-----------------------------------------------------------------------------
//
// Configure the UART0 using Timer1, for <baudrate> and 8-N-1. In order to
// increase the clocking flexibility of Timer0, Timer1 is configured to count
// SYSCLKs. 
// 
// To use this routine SYSCLK/BAUDRATE/16 must be less than 256. For example,
// if SYSCLK = 50 MHz, the lowest standard baud rate supported by this
// routine is 19,200 bps. 
//
void UART0_Init (void)
{
   char SFRPAGE_SAVE = SFRPAGE;     // Save Current SFR page
   
   SFRPAGE = UART0_PAGE;

   SCON0  = 0x50;                   // SCON0: mode 0, 8-bit UART, enable RX
   SSTA0  = 0x10;                   // Timer 1 generates UART0 baud rate and
                                    // UART0 baud rate divide by two disabled
   SFRPAGE = TIMER01_PAGE;
   TMOD   &= ~0xF0;                  
   TMOD   |=  0x20;                 // TMOD: timer 1, mode 2, 8-bit reload
   
   TH1 = -(SYSCLK/BAUDRATE/16);     // Set the Timer1 reload value
                                    // When using a low baud rate, this equation
                                    // should be checked to ensure that the
                                    // reload value will fit in 8-bits.
                                                           
   CKCON |= 0x10;                   // T1M = 1; SCA1:0 = xx
   

   TL1 = TH1;                       // initialize Timer1
   TR1 = 1;                         // start Timer1  
   
   SFRPAGE = UART0_PAGE;
   TI0 = 1;                         // Indicate TX0 ready
   
   SFRPAGE = SFRPAGE_SAVE;          // Restore SFR page
}