ntc.c

/*
        Thymio-II Firmware

        Copyright (C) 2011 Philippe Retornaz <philippe dot retornaz at epfl dot ch>,
        Mobots group (http://mobots.epfl.ch), Robotics system laboratory (http://lsro.epfl.ch)
        EPFL Ecole polytechnique federale de Lausanne (http://www.epfl.ch)

        See authors.txt for more details about other contributors.

        This program is free software: you can redistribute it and/or modify
        it under the terms of the GNU Lesser General Public License as published
        by the Free Software Foundation, version 3 of the License.

        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 Lesser General Public License for more details.

        You should have received a copy of the GNU Lesser General Public License
        along with this program. If not, see <http://www.gnu.org/licenses/>.
*/

#include <types/types.h>
#include <clock/clock.h>
#include <error/error.h>

#include "ntc.h"
#include "regulator.h"

static ntc_cb cb;
static unsigned int calib;

#define calib_off() do {_LATF3 = 0; }while(0)
#define ntc_off() do{_LATB13 = 0;  _LATF3 = 0;} while(0)
#define discharge_mode() do{_TRISG6 = 0; _TRISB13 = 0; } while(0)
#define mesure_mode() do{_TRISG6 = 1; } while(0)
#define calib_mode() do{_TRISG6 = 1; _TRISB13 = 1;} while(0)

#define comparator_output_enable() do {_TRISG7 = 0; CM1CONbits.COE = 1;}while(0)
#define comparator_output_disable() do{_TRISG7 = 1; CM1CONbits.COE = 0;}while(0)


#define R_CALIB 10000


unsigned long __udiv3216(unsigned long, unsigned int);

void _ISR _IC8Interrupt(void) {
	unsigned int temp;
	_IC8IF = 0;
	temp = IC8BUF;
	
	// All the mesurments are one-shots. 
	// Disable the module
	IC8CON1bits.ICM = 0x0;
	comparator_output_disable();
	
	if(!_TRISB13) {
		temp = __udiv3216(__builtin_muluu(temp,R_CALIB),calib);
		
		// Temp = 250 - (Rm - 5000)/9
		
		temp = (250*9 - ((int) temp) + 5000) / 9;
		
		ntc_off();
	} else {
		// Calibration
		if(calib)	
			calib = (__builtin_muluu(calib, 15) + temp + 8) >> 4;
		else
			calib = temp;
		calib_off();
	}
	if(cb)		
		cb(temp);
	
	discharge_mode();
}

	
static void calibrate(void) {
	int counter = 0;
	mesure_mode();
	
	calib = 0;
	
	comparator_output_enable();
	
	asm volatile(	"disi #2\n"
			"bset IC8CON1, #0\n" 
			"bset LATF, #3\n");
	
	while(!calib && counter++ < 1000) {
		clock_delay_us(10);
	}
}


void ntc_init(ntc_cb mes_done, int prio) {
	va_get(); // We are going to put 3.3 on IR receiver ... need to power it up.
	
	// Discharge circuit
	_LATG6 = 0;
	_TRISG6 = 0;
	_LATF3 = 0;
	_TRISF3 = 0;
	_LATB13 = 0;
	_TRISB13 = 1;
	clock_delay_us(1000);
	
	// Init voltage reference @ 2.06V (around 62.5% Vcc)
	_CVRR = 0;
	_CVR = 15;
	_CVRSS = 0; // Vdd/Vss range
	_CVREN = 1;
	
	// Init comparator
	CM1CONbits.CREF = 1; // CVref input
	CM1CONbits.CCH = 0x2; // C1IND input
	
	CM1CONbits.CEN = 1;
	
	clock_delay_us(10); // Comparator stabilisation time ...
	
	// Init the IC8.
	IC8CON2 = 0;
	IC8CON1 = 0;
	IC8CON1bits.ICTSEL = 7; // Fcy
	_IC8IF = 0;
	_IC8IE = 1;
	_IC8IP = prio;
	
	cb = 0;
	calibrate();
	
	_TRISB13 = 0;
	
	cb = mes_done;
}

void ntc_shutdown(void) {
	// Force everything to 0
	_LATG6  = 0;
	_LATF3 = 0;
	_LATB13 = 0;
	_TRISG6 = 0;
	_TRISF3 = 0;
	_TRISB13 = 0;
	
	// Shutdown Comparator 
	CM1CONbits.CEN = 0;
	
	// Shutdown voltage reference
	_CVREN = 0;
	
	// Shutdown IC
	IC8CON1 = 0;
	_IC8IE = 0;
	
	va_put();
}


void ntc_calibrate(void) {
	
	calib_mode();
	
	comparator_output_enable();
	
	asm volatile("disi #2\n"
				"bset IC8CON1, #0\n"
				"bset LATF, #3\n");
	
}


void ntc_mesure(void) {
	
	mesure_mode();
	
	comparator_output_enable();
	
	asm volatile(	"disi #3\n"
			"bset IC8CON1, #0\n"
			"bset LATB, #13\n"
			"bset LATF, #3\n");
	
}