freq_gen1.c

c8051f020开发板的所有参考程序

//-----------------------------------------------------------------------------
// Freq_Gen1.c
//-----------------------------------------------------------------------------
// Copyright 2002 Cygnal Integrated Products, Inc.
//
// AUTH: BW
// DATE: 09 APR 02
//
// This program uses the PCA in Frequency Output mode to generate a square
// wave on P0.0.
//
// Target: C8051F02x
// Tool chain: KEIL C51 6.03 / KEIL EVAL C51
//

//-----------------------------------------------------------------------------
// Includes
//-----------------------------------------------------------------------------

#include <c8051f020.h>                 // SFR declarations

//-----------------------------------------------------------------------------
// 16-bit SFR Definitions for 'F02x
//-----------------------------------------------------------------------------

sfr16 DP       = 0x82;                 // data pointer
sfr16 TMR3RL   = 0x92;                 // Timer3 reload value
sfr16 TMR3     = 0x94;                 // Timer3 counter
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 T2       = 0xcc;                 // Timer2
sfr16 RCAP4    = 0xe4;                 // Timer4 capture/reload
sfr16 T4       = 0xf4;                 // Timer4
sfr16 DAC0     = 0xd2;                 // DAC0 data
sfr16 DAC1     = 0xd5;                 // DAC1 data

//-----------------------------------------------------------------------------
// Global CONSTANTS
//-----------------------------------------------------------------------------

#define SYSCLK       22118400          // SYSCLK frequency in Hz
#define FREQ         172800            // Frequency to generate in Hz
#define BAUDRATE     9600              // Baud rate of UART in bps

sbit LED = P1^6;                       // LED = 1 means ON

//-----------------------------------------------------------------------------
// Structures, Unions, Enumerations, and Type definitions
//-----------------------------------------------------------------------------

typedef union ULong {
   long Long;
   unsigned int UInt[2];
   unsigned char Char[4];
} ULong;

//-----------------------------------------------------------------------------
// Function PROTOTYPES
//-----------------------------------------------------------------------------

void SYSCLK_Init (void);
void PORT_Init (void);
void PCA0_Init (void);

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

void main (void) {

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

   SYSCLK_Init ();                     // initialize oscillator
   PORT_Init ();                       // initialize crossbar and GPIO
   PCA0_Init ();                       // initialize PCA0
   while (1);
}

//-----------------------------------------------------------------------------
// Initialization Subroutines
//-----------------------------------------------------------------------------

//-----------------------------------------------------------------------------
// SYSCLK_Init
//-----------------------------------------------------------------------------
//
// This routine initializes the system clocks
//
void SYSCLK_Init (void)
{
   int i;                              // delay counter

   OSCXCN = 0x67;                      // start external oscillator

   for (i=0; i < 256; i++) ;           // wait for osc to start up

   while (!(OSCXCN & 0x80)) ;          // Wait for crystal osc. to settle

   OSCICN = 0x88;                      // select external oscillator as
                                       // system clock source and enable
                                       // missing clock detector
}

//-----------------------------------------------------------------------------
// PORT_Init
//-----------------------------------------------------------------------------
//
// Configure the Crossbar and GPIO ports
//
void PORT_Init (void)
{
   XBR0    |= 0x08;                    // Enable CEX0 on P0.0
   XBR2    |= 0x40;                    // Enable crossbar and weak pull-ups
   P0MDOUT |= 0x01;                    // enable P0.0 as a push-pull output
}

//-----------------------------------------------------------------------------
// PCA0_Init
//-----------------------------------------------------------------------------
//
// Configure PCA0:  PCA uses SYSCLK as time base; overflow interrupt
// disabled.
// Module 0 configured in Frequency Output mode to generate a frequency equal
// to the constant FREQ.
//
void PCA0_Init (void)
{
   // configure PCA time base to use SYSCLK; overflow interrupt disabled
   PCA0CN = 0x00;                      // Stop counter; clear all flags
   PCA0MD = 0x08;                      // Time base uses SYSCLK

   // Configure Module 0 to Frequency Output mode to toggle at 2*FREQ
   PCA0CPM0 = 0x46;                    // Frequency Output mode
   PCA0CPH0 = SYSCLK/FREQ/2;           // Set frequency

   // Start PCA counter
   CR = 1;
}