agc.c

ADS-B接收机DIY全套资料

/*********************************************************************
 * FileName:        agc.c
 * Dependencies:    See INCLUDES section below
 * Processor:       PIC18
 * Compiler:        C18 2.30.01+
 * Company:         sprut
 * Copyright:       2007-2010 Joerg Bredendiek (sprut)
 *
 *
 ********************************************************************/

/*
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */



/** I N C L U D E S **********************************************************/
#include <p18cxxx.h>
#include <usart.h>
#include "system\typedefs.h"
#include "system\usb\usb.h"
#include "io_cfg.h"             // I/O pin mapping

#include "delays.h"
//#include "system\interrupt\interrupt.h"
#include "user\user.h"
#include "user\adsbin.h"
#include "user\agc.h"


/** V A R I A B L E S ********************************************************/
#pragma udata


/** D E C L A R A T I O N S **************************************************/
#pragma code


void agc_init(void)
{
	// init COMP: Mode 001
	CMCON = 1;


	// init Ureferenz    0 .. 3,125 V
	// U =  zahl/24 *5 = zahl * 208mV
	CVRCON = 0xE5;			// 5 * 208mV = 1V an RA2


	// init ADC: input ist RA1
	// AN0 - Comp,vin-  (mit AN2 verbunden)
	// AN1 - Pegel
	// AN2 - Vref fuer Comparator (mit AN0 verbunden)

	ADCON0 = 0x05;				// AN1, idle, enabled
	ADCON1 = 0x0D;				// nur AN0 und AN1 analog
	//ADCON0 = 0x01;				// AN0, idle, enabled
	//ADCON1 = 0x0E;				// nur AN0 analog
	ADCON2 = 0xFE;				// rechts, 20 Tad, Fosc/64
}


// stellt Comparatorpegel neu ein
// auf HF-Pegel +200..400 mV
byte agc_avr(void)
{
	word pegel = agc_Pegel();		// HF-Pegel in mV
	byte step = pegel/200 + 2;		// in Ref-Stfen a 200 mV umrechnen
	if (step>15) step=15;			// ohoh, das ist viel zu viel
	CVRCON = 0xE0 | step;			// Spannung einstellen
	return step;
}


//misst HF-Pegel
// Ergebnis in mV
word agc_Pegel(void)
{

	ADCON0 = 0x05;					// Pegel, AN0, idle, enabled
	SleepMs(1);
	return agc_Adc();
}


//misst Ref-Pegel
// Ergebnis in mV
word agc_Ref(void)
{
	ADCON0 = 0x01;					// Referenz, AN1, idle, enabled
	SleepMs(1);
	return agc_Adc();
}


//misst ADC-Eingangsspannung
// Ergebnis in mV
word agc_Adc(void)
{
	WORD	wert;
	ADCON0bits.GO = 1;              // Start AD conversion
	while(ADCON0bits.NOT_DONE);     // Wait for conversion
    wert.byte0 = ADRESL;
    wert.byte1 = ADRESH;
	wert._word *= 5;				// Wandlung in mV
	return wert._word;
}


/** EOF agc.c ***************************************************************/