f500_ports_switchled.c

C8051F500开发编程：MCU全部资源应用实例

//-----------------------------------------------------------------------------
// F500_Ports_SwitchLED.c
//-----------------------------------------------------------------------------
// Copyright 2008 Silicon Laboratories, Inc.
// http://www.silabs.com
//
// Program Description:
//
// This program demonstrates how to configure port pins as digital inputs
// and outputs.  The C8051F500 target board has one push-button switch
// connected to a port pin and one LED.  The program constantly checks the
// status of the switch and if it is pushed, it turns on the LED.
//
// Resources Used:
// * Internal Oscillator: MCU clock source
//
// How To Test:
//
// 1) Download code to a 'F500 target board
// 2) Ensure that the Switch and LED pins on the J19 header are
//    properly shorted
// 3) Push the button (P0.7) and see that the LED turns on
//
//
// Target:         C8051F500 (Side A of a C8051F500-TB)
// Tool chain:     Keil C51 7.50 / Keil EVAL C51
// Command Line:   None
//
// Release 1.1 / 11 JUN 2008 (ADT)
//    -Edited formatting
//
// Release 1.0 / 03 MAR 2008 (GP)
//    -Initial Revision

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

#include <compiler_defs.h>
#include <C8051F500_defs.h>            // SFR declarations

//-----------------------------------------------------------------------------
// Pin Declarations
//-----------------------------------------------------------------------------

SBIT (LED, SFR_P1, 3);                 // LED == 1 means ON
SBIT (SW1, SFR_P1, 4);                 // SW1 == 0 means switch depressed

//-----------------------------------------------------------------------------
// Function Prototypes
//-----------------------------------------------------------------------------

void OSCILLATOR_Init (void);
void PORT_Init (void);

//-----------------------------------------------------------------------------
// main() Routine
//-----------------------------------------------------------------------------

void main (void)
{
   SFRPAGE = ACTIVE_PAGE;              // Set SFR Page for PCA0MD

   PCA0MD &= ~0x40;                    // Disable the watchdog timer

   PORT_Init ();                       // Initialize Port I/O
   OSCILLATOR_Init ();                 // Initialize Oscillator

   while (1)
   {
      if (SW1 == 0)                    // If switch depressed
      {
         LED = 1;                      // Turn on LED
      }
      else
      {
         LED = 0;                      // Else, turn it off
      }
   }                                   // end of while(1)
}                                      // end of main()

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

//-----------------------------------------------------------------------------
// OSCILLATOR_Init
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters   : None
//
// This function initializes the system clock to use the internal oscillator
// at its maximum frequency / 8.
//
//-----------------------------------------------------------------------------

void OSCILLATOR_Init (void)
{
   U8 SFRPAGE_save = SFRPAGE;
   SFRPAGE = CONFIG_PAGE;

   OSCICN = 0x84;                      // Configure internal oscillator for
                                       // 24 MHz / 8

   SFRPAGE = ACTIVE_PAGE;

   RSTSRC = 0x04;                      // Enable missing clock detector

   SFRPAGE = SFRPAGE_save;
}

//-----------------------------------------------------------------------------
// PORT_Init
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters   : None
//
// This function configures the crossbar and ports pins.
//
// To configure a pin as a digital input, the pin is configured as digital
// and open-drain and the port latch should be set to a '1'.  The weak-pullups
// are used to pull the pins high.  Pressing the switch pulls the pins low.
//
// To configure a pin as a digital output, the pin is configured as digital
// and push-pull.
//
// An output pin can also be configured to be an open-drain output if system
// requires it.  For example, if the pin is an output on a multi-device bus,
// it will probably be configured as an open-drain output instead of a
// push-pull output.  For the purposes of this example, the pin is configured
// as push-pull output because the pin in only connected to an LED.
//
// P1.3   digital   push-pull     LED
// P1.4   digital   open-drain    SW1
//-----------------------------------------------------------------------------
void PORT_Init (void)
{
   U8 SFRPAGE_save = SFRPAGE;
   SFRPAGE = CONFIG_PAGE;

   P1MDIN |= 0x08;                     // P1.3 is digital
   P1MDIN |= 0x10;                     // P1.4 is digital

   P1MDOUT |= 0x08;                    // P1.3 is push-pull
   P1MDOUT &= ~0x10;                   // P1.4 is open-drain

   P1     |= 0x10;                     // Set P1.4 latch to '1'

   XBR2    = 0x40;                     // Enable crossbar and enable
                                       // weak pull-ups

   SFRPAGE = SFRPAGE_save;
}


//-----------------------------------------------------------------------------
// End Of File
//-----------------------------------------------------------------------------