temp_3.c

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//-----------------------------------------------------------------------------
// Temp_3.c
//-----------------------------------------------------------------------------
// Copyright (C) 2005 Silicon Laboratories, Inc.
//
// AUTH: BW / FB
// DATE: 06 FEB 03
//
// This program prints the C8051F124 die temperature out the hardware
// UART at 115200bps. This example uses the internal 24.5MHz oscillator
// multiplied by 2 using the on-chip PLL (SYSCLK = 49MHz).
//
// The ADC is configured to look at the on-chip temp sensor.  The sampling
// rate of the ADC is determined by the constant <SAMPLE_RATE>, which is given
// in Hz.
//
// The ADC0 End of Conversion Interrupt Handler retrieves the sample
// from the ADC and adds it to a running accumulator.  Every <INT_DEC>
// samples, the ADC updates and stores its result in the global variable
// <temperature>, which holds the current temperature in hundredths of a
// degree.  The sampling technique of adding a set of values and
// decimating them (posting results every (n)th sample) is called 'integrate
// and dump.'  It is easy to implement and requires very few resources.
//
// For each power of 4 of <INT_DEC>, you gain 1 bit of effective resolution.
// For example, <INT_DEC> = 256 gain you 4 bits of resolution: 4^4 = 256.
//
// Also note that the ADC0 is configured for 'LEFT' justified mode.  In this
// mode, the MSB of the ADC word is located in the MSB position of the ADC0
// high byte.  Using the data in this way makes the magnitude of the resulting
// code independent of the number of bits in the ADC (12- and 10-bits behave
// the same).
//
// Target: C8051F12x
//

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

#include <ioC8051f124.h>                 // SFR declarations
#include "page_defs.h"
#include <stdio.h>

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

__sfr __no_init volatile unsigned short DP       @ 0x82;                 // data pointer
__sfr __no_init volatile unsigned short ADC0     @ 0xbe;                 // ADC0 data
__sfr __no_init volatile unsigned short ADC0GT   @ 0xc4;                 // ADC0 greater than window
__sfr __no_init volatile unsigned short ADC0LT   @ 0xc6;                 // ADC0 less than window
__sfr __no_init volatile unsigned short RCAP    @ 0xca;
__sfr __no_init volatile unsigned short TMR     @ 0xcc;
__sfr __no_init volatile unsigned short DAC0     @ 0xd2;                 // DAC0 data
__sfr __no_init volatile unsigned short DAC1     @ 0xd2;                 // DAC1 data
__sfr __no_init volatile unsigned short PCA0CP5  @ 0xe1;                 // PCA0 Module 5 capture
__sfr __no_init volatile unsigned short PCA0CP2  @ 0xe9;                 // PCA0 Module 2 capture
__sfr __no_init volatile unsigned short PCA0CP3  @ 0xeb;                 // PCA0 Module 3 capture
__sfr __no_init volatile unsigned short PCA0CP4  @ 0xed;                 // PCA0 Module 4 capture
__sfr __no_init volatile unsigned short PCA0     @ 0xf9;                 // PCA0 counter
__sfr __no_init volatile unsigned short PCA0CP0  @ 0xfb;                 // PCA0 Module 0 capture
__sfr __no_init volatile unsigned short PCA0CP1  @ 0xfd;                 // PCA0 Module 1 capture

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

#define BAUDRATE     9600            // Baud rate of UART in bps
#define INTCLK       24500000          // Internal oscillator frequency in Hz
#define SYSCLK       49000000          // Output of PLL derived from (INTCLK*2)
#define SAMPLE_RATE  50000             // Sample frequency in Hz
#define INT_DEC      256               // integrate and decimate ratio

#define LED P1_bit.P16                       // LED='1' means ON
#define SW1 P3_bit.P37                       // SW1='0' means switch pressed

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

void SYSCLK_Init (void);
void PORT_Init (void);
void UART1_Init (void);
void ADC0_Init (void);
void Timer3_Init (int counts);
__interrupt void ADC0_ISR (void);
void wait_ms (int ms);
//-----------------------------------------------------------------------------
// Global VARIABLES
//-----------------------------------------------------------------------------

long result;                           // ADC0 decimated value

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

void main (void) {
   long temperature;                   // temperature in hundredths of a
                                       // degree C
   int temp_int, temp_frac;            // integer and fractional portions of
                                       // temperature

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

   SYSCLK_Init ();                     // initialize oscillator
   PORT_Init ();                       // initialize crossbar and GPIO
   UART1_Init ();                      // initialize UART1
   Timer3_Init (SYSCLK/SAMPLE_RATE);   // initialize Timer3 to overflow at
                                       // sample rate

   ADC0_Init ();                       // init ADC

   SFRPAGE = ADC0_PAGE;
   ADC0CN_bit.AD0EN = 1;                          // enable ADC

   IE_bit.EA = 1;                             // Enable global interrupts

   while (1) {
      IE_bit.EA = 0;                          // disable interrupts
      temperature = result;
      IE_bit.EA = 1;                          // re-enable interrupts

      // calculate temperature in hundredths of a degree
      temperature = temperature - 42380;
      temperature = (temperature * 100L) / 156;
      temp_int = temperature / 100;
      temp_frac = temperature - (temp_int * 100);

      SFRPAGE = UART1_PAGE;
      printf ("Temperature is %+02d.%02d\n", temp_int, temp_frac);

      SFRPAGE = CONFIG_PAGE;
      LED = ~SW1;                      // LED reflects state of switch

      wait_ms(50);                     // wait 50 milliseconds
   }
}

//-----------------------------------------------------------------------------
// Support Subroutines
//-----------------------------------------------------------------------------

//-----------------------------------------------------------------------------
// wait_ms
//-----------------------------------------------------------------------------
//
// This routine inserts a delay of <ms> milliseconds.
//
void wait_ms(int ms)
{
   char SFRPAGE_SAVE = SFRPAGE;        // Save Current SFR page

   SFRPAGE = TMR2_PAGE;

   TMR2CN = 0x00;                      // Stop Timer3; Clear TF3;
   TMR2CF = 0x00;                      // use SYSCLK/12 as timebase

//   RCAP2 = -(SYSCLK/1000/12);          // Timer 2 overflows at 1 kHz
//   TMR2 = RCAP2;
   RCAP = -(SYSCLK/1000/12);          // Timer 2 overflows at 1 kHz
   TMR = RCAP;

   IE_bit.ET2 = 0;                            // Disable Timer 2 interrupts

   TMR2CN_bit.TR2 = 1;                            // Start Timer 2

   while(ms){
      TMR2CN_bit.TF2 = 0;
      while(!TMR2CN_bit.TF2);                     // wait until timer overflows
      ms--;                            // decrement ms
   }

   TMR2CN_bit.TR2 = 0;                            // Stop Timer 2

   SFRPAGE = SFRPAGE_SAVE;             // Restore SFRPAGE
}

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

//-----------------------------------------------------------------------------
// SYSCLK_Init
//-----------------------------------------------------------------------------
//
// This routine initializes the system clock to use the internal oscillator
// at 24.5 MHz multiplied by two using the PLL.
//
void SYSCLK_Init (void)
{