78 lines
2.5 KiB
C
78 lines
2.5 KiB
C
/* adccalib.c -- ADC calibration of internal temperature sensor */
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/* Copyright (c) 2020-2021 Renaud Fivet */
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#include <stdio.h>
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#include "system.h" /* uptime, adc_vnt() */
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#include "ds18b20.h" /* ds18b20_() */
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#define ABS( i) ((i < 0) ? -i : i)
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static void track( short *minp, short *maxp, short val) {
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if( val < *minp)
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*minp = val ;
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if( val > *maxp)
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*maxp = val ;
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}
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int main( void) {
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unsigned last = 0 ;
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short calV, calC ;
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short minC, maxC ; /* Track temperature from DS18B20 */
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short minV, maxV ; /* Track ADC raw Vref */
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short minT, maxT ; /* Track ADC raw Tsense */
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minC = minV = minT = 0x7FFF ;
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maxC = maxV = maxT = -32768 ;
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/* Initialize ADC and fetch calibration values */
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adc_vnt( VNT_INIT, &calV, &calC) ;
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printf( "%u, %u\n", calV, calC) ;
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int tconst = 6660 * calV / calC ;
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/* Initialize DS18B20 and initiate temperature conversion */
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ds18b20_init() ;
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ds18b20_resolution( 12) ; /* Set highest resolution: 12 bits */
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ds18b20_convert() ; /* start temperature conversion */
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/* main acquisition loop, reads samples every seconds */
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for( ;;)
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if( uptime == last)
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yield() ;
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else {
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short Vsample, Csample ;
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last = uptime ;
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/* Track DS18B20 temperature readings */
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switch( ds18b20_fetch( &Csample)) {
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case DS18B20_SUCCESS:
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track( &minC, &maxC, Csample) ;
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printf( "%i.%i, %i, %i, ", Csample / 10, ABS( Csample % 10),
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minC, maxC) ;
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break ;
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case DS18B20_FAIL_TOUT:
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printf( "Timeout, ") ;
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break ;
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case DS18B20_FAIL_CRC:
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printf( "CRC Error, ") ;
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}
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ds18b20_convert() ; /* start temperature conversion */
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/* Track Internal Temperature Sensor readings */
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adc_vnt( VNT_RAW, &Vsample, &Csample) ;
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track( &minV, &maxV, Vsample) ;
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track( &minT, &maxT, Csample) ;
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printf( "%i, %i, %i, %i, %i, %i, %i, %i, ",
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calV, Vsample, minV, maxV,
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calC, Csample, minT, maxT) ;
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Csample = 3630 - (1 + tconst * Csample / Vsample) / 2 ;
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Vsample = (660 * calV / Vsample + 1) / 2 ;
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printf( "%i.%i, %i.%i\n", Vsample / 100, ABS( Vsample % 100),
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Csample / 10, ABS( Csample % 10)) ;
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}
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}
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/* end of adccalib.c */
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