temp_3.c

来自「8051试验程序 基础教材」· C语言 代码 · 共 277 行

// -----------------------------------------------------------------------------
// Temp_3.c
// -----------------------------------------------------------------------------
// Copyright (C) 2005 Silicon Laboratories, Inc.
//
// AUTH: BW
// DATE: 23 JUL 01
//
// This program prints the C8051F0xx die temperature out the hardware
// UART at 9600bps. Assumes an 18.432MHz crystal is attached between
// XTAL1 and XTAL2.
//
// 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: C8051F00x or C8051F01x
// Tool chain: IAR Systems EW8051

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

#include <ioC8051f000.h>	// SFR declarations
#include <stdio.h>

// -----------------------------------------------------------------------------
// 16-bit SFR Definitions for 'F00x
// -----------------------------------------------------------------------------

__sfr __no_init volatile unsigned short DP 		@ 0x82;	// data pointer
__sfr __no_init volatile unsigned short TMR3RL 	@ 0x92;	// Timer3 reload value
__sfr __no_init volatile unsigned short TMR3 	@ 0x94;	// Timer3 counter
__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 RCAP2 	@ 0xca;	// Timer2 capture/reload
__sfr __no_init volatile unsigned short T2 		@ 0xcc;	// Timer2
__sfr __no_init volatile unsigned short DAC0 	@ 0xd2;	// DAC0 data
__sfr __no_init volatile unsigned short DAC1 	@ 0xd5;	// DAC1 data

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

#define BAUDRATE     9600		// Baud rate of UART in bps
#define SYSCLK       18432000	// SYSCLK frequency in Hz
#define SAMPLE_RATE  50000		// Sample frequency in Hz
#define INT_DEC      4096		// integrate and decimate ratio

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

#define ADCEN ADC0CN_bit.ADCEN
#define EA IE_bit.EA
#define TR1 TCON_bit.TR1
#define TI SCON_bit.TI
#define ADCINT ADC0CN_bit.ADCINT

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

void SYSCLK_Init(void);
void PORT_Init(void);
void UART0_Init(void);
void ADC0_Init(void);
void Timer3_Init(int counts);
__interrupt void ADC0_ISR(void);

// -----------------------------------------------------------------------------
// 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
    UART0_Init();				// initialize UART0

    Timer3_Init(SYSCLK / SAMPLE_RATE);		// initialize Timer3 to overflow
    										// at sample rate
    ADC0_Init();				// init ADC

    ADCEN = 1;					// enable ADC

    EA = 1;						// Enable global interrupts

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

		// calculate temperature in hundredths of a degree
		temperature = temperature - 42880;
		temperature = (temperature * 100L) / 156;
		temp_int = temperature / 100;
		temp_frac = temperature - (temp_int * 100);
		printf("Temperature is %+02d.%02d\n", temp_int, temp_frac);

		LED = ~SW1;				// LED reflects state of switch
    }
}

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

// -----------------------------------------------------------------------------
// SYSCLK_Init
// -----------------------------------------------------------------------------
//
// This routine initializes the system clock to use an 22.1184MHz crystal
// as its clock source.
//
void SYSCLK_Init(void)
{
    int i;						// delay counter

    OSCXCN = 0x67;				// start external oscillator with
    							// 18.432MHz crystal

    for (i = 0; i < 256; i++);	// XTLVLD blanking interval (>1ms)

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

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

// -----------------------------------------------------------------------------
// PORT_Init
// -----------------------------------------------------------------------------
//
// Configure the Crossbar and GPIO ports
//
void PORT_Init(void)
{
    XBR0 = 0x04;		// Enable UART0
    XBR1 = 0x00;
    XBR2 = 0x40;		// Enable crossbar and weak pull-ups
    PRT0CF |= 0x01;		// enable TX0 as a push-pull output
    PRT1CF |= 0x40;		// enable P1.6 (LED) as push-pull output
}

// -----------------------------------------------------------------------------
// UART0_Init
// -----------------------------------------------------------------------------
//
// Configure the UART using Timer1, for <baudrate> and 8-N-1.
//
void UART0_Init(void)
{
    SCON = 0x50;						// SCON: mode 1, 8-bit UART, enable RX
    TMOD = 0x20;						// TMOD: timer 1, mode 2, 8-bit reload
    TH1 = -(SYSCLK / BAUDRATE / 16);	// set Timer1 reload value for baudrate
    TR1 = 1;							// start Timer1
    CKCON |= 0x10;						// Timer1 uses SYSCLK as time base
    PCON |= 0x80;						// SMOD = 1
    TI = 1;								// Indicate TX ready
}

// -----------------------------------------------------------------------------
// ADC0_Init
// -----------------------------------------------------------------------------
//
// Configure ADC0 to use Timer3 overflows as conversion source, to
// generate an interrupt on conversion complete, and to use left-justified
// output mode.  Enables ADC end of conversion interrupt. Leaves ADC
// disabled.
//
void ADC0_Init(void)
{
    ADC0CN = 0x05;		// ADC0 disabled; normal tracking
    					// mode; ADC0 conversions are initiated
    					// on overflow of Timer3; ADC0 data is
    					// left-justified

    REF0CN = 0x07;		// enable temp sensor, on-chip VREF,
					    // and VREF output buffer

    AMX0SL = 0x0f;		// Select TEMP sens as ADC mux output
    ADC0CF = 0x80;		// ADC conversion clock = SYSCLK/16
    ADC0CF |= 0x01;		// PGA gain = 2

    EIE2 |= 0x02;		// enable ADC interrupts
}

// -----------------------------------------------------------------------------
// Timer3_Init
// -----------------------------------------------------------------------------
//
// Configure Timer3 to auto-reload at interval specified by <counts> (no
// interrupt generated) using SYSCLK as its time base.
//
void Timer3_Init(int counts)
{
    TMR3CN = 0x02;		// Stop Timer3; Clear TF3;
					    // use SYSCLK as timebase

    TMR3RL = -counts;	// Init reload values
    TMR3 = 0xffff;		// set to reload immediately
    EIE2 &= ~0x01;		// disable Timer3 interrupts
    TMR3CN |= 0x04;		// start Timer3
}

// -----------------------------------------------------------------------------
// Interrupt Service Routines
// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------
// ADC0_ISR
// -----------------------------------------------------------------------------
//
// ADC0 end-of-conversion ISR
// Here we take the ADC0 sample, add it to a running total <accumulator>,
// and decrement our local decimation counter <int_dec>.
// When <int_dec> reaches  zero, we post the decimated result in
// the global variable <result>.

#pragma vector=0x7B
__interrupt void ADC0_ISR(void)
{
    static unsigned int_dec = INT_DEC;	// integrate/decimate counter
									    // we post a new result when
									    // int_dec = 0

    static long accumulator = 0L;		// here's where we integrate the
    									// ADC samples

    ADCINT = 0;							// clear ADC conversion complete
    									// indicator

    accumulator += ADC0;				// read ADC value and add to running
    									// total

    int_dec--;							// update decimation counter

    if (int_dec == 0) {					// if zero, then post result
		int_dec = INT_DEC;				// reset counter
		result = accumulator >> 12;
		accumulator = 0L;				// reset accumulator
    }
}