/***************************************************************************
 * This code and information is provided "as is" without warranty of any   *
 * kind, either expressed or implied, including but not limited to the     *
 * implied warranties of merchantability and/or fitness for a particular   *
 * purpose.                                                                *
 *                                                                         *
 * Copyright (C) 2005 Teridian Semiconductor Corp. All Rights Reserved.    *
 ***************************************************************************/
//**************************************************************************
//  DESCRIPTION: 71M652x POWER METER - battery test code.
//  If BME, bit 6 of 0x2020, is set, then a load is applied and on the
//  next alternate conversion cycle, the battery voltage is measured.
//  Since this loads the battery, it should be as short as possible,
//  and done only rarely, e.g. once per day.
//  Therefore, the real-time logic is in the CE interrupts in ce.c
//  In xfer_busy, which starts the almux cycle to mesure temperature,
//  there's code to start a battery test.  In ce-busy, which runs
//  after every mux cycle, there's code to collect the battery test
//  data.
//  The code here commands the battery test, and then interprets it.
// 
//  AUTHOR:  RGV
//
//  HISTORY: See end of file.
//**************************************************************************
// File: BATTEST.C
//               
#include "options.h"
#if BATTERY_TEST
#include "meter.h"       // access to day of month
#include "ce.h"          // memget_ce()
#include "lcd.h"         // liquid crystal display
#include "battest.h"     // test the fn prototypes
                                                                              
/*** External variables referenced by this module ***/
// See "math.h"
// Refer to "ce652x.h"  include file.
// VBat is in Totals, in meter.h (so it can be displayed, saved, etc.)
// VBatMin is in Totals.Parms, in meter.h (so it can be calibrated)

/*** Public variables declared within this module ***/
uint8_t data bat_sample_cnt = 0;  // counts samples not yet collected
int32_t xdata bat_samples; // sum of samples

/*** Private functions declared within this module ***/
static int32_t mVBat (int32_t v); // calculate the battery voltage, in mV

/*** Private variables declared within this module ***/
#if REAL_TIME_DATE
static uint8_t last_day = 0;  // the last day that a battery test was done
#elif OPERATING_TIME
static uint32_t last_day = 0;  // the last day that a battery test was done
#else
#error battery test needs a way to find the next day
#endif

// This routine may be called from the command line to start a battery
// test.  The xfer_busy_interrupt, in ce.c, reads bat_sample_cnt to start
// a measurement.
void battest_start (void)
{
    if (bat_sample_cnt)  // if a measurement is in progress, don't mess it up
        return;
    #if REAL_TIME_DATE
    last_day = Rtc_Date;
    #elif OPERATING_TIME
    last_day = OperatingSeconds + 86400L;
    #else
    #error needs a day sensor
    #endif
    LCDX |= BME;  // start reading the battery
    bat_sample_cnt = 3;
}

// This routine is called from the part of meter_run() that only
// operates when the CE is active.  This is because the battery test
// can only run when the CE is active.  It can't run in brownout mode,
// for example.
void battest_run (void)
{
    // Schedule a battery test every day at midnight, and ASAP when the meter 
    // is turned on.  With a 3.6V battery at the worst case battery load 
    // resistor, 27 kiloOhms, this nominally draws 133 microamps for 
    // 2 seconds each day. 
    // If mains power never fails, this depletes a 1Amp/Hour battery 
    // (typical small 3.6V lithium) in ten years.
    #if REAL_TIME_DATE
    if (last_day != Rtc_Date)
    #elif OPERATING_TIME
    if (last_day < OperatingSeconds)
    #else
    #error needs a day sensor
    #endif
    {
        battest_start ();
    } 
    else if (bat_sample_cnt > 0)
    {
        --bat_sample_cnt;
        if (bat_sample_cnt == 0)
        {
            VBat = ((uint32_t) memget_ce (&vbat) ) >> 9;
            LCDX &= ~BME;  // stop measuring
        }
    }
    // if mesurement is done, and the battery exists
    else if (bat_sample_cnt == BATTERY_MODE_ENABLE)
    {
        // report the results
        // VBatMin can be calibrated. It's in the parameter table 
        // in meter\meter.h with other calibrations.
        // NOT AN ERROR!! The ADC count is bigger for smaller VBat voltage
        if (VBat > VBatMin) // e.g. 0V = 7FFFFF adc counts, 5V = 0x600000
        {
            // report an error
            Status |= BATTERY_BAD;
        }
        else
        {
            // report a success
            Status &= ~BATTERY_BAD;
        }
    }
}

// display the most recent battery voltage on the LCD
void battest_lcd (void) // there's only one battery! Don't pass the value.
{
   LCD_Number (mVBat(VBat), 6, 3);     
   LCD_3DP ();		  	// Three decimal places.
   battest_start ();  	// start another measurement, so display adjusts
}

// calculate the battery voltage in millivolts
int32_t mVBat (int32_t v)
{
    // The ADC sample has to be shifted right 9 bits.  
    // So the float constant (-2.298e-6, from official testing) is divided by 2.
    // The most accurate place in the ADC is 3.3V, roughly 0x69d800
    // For a perfectly accurate scheme, the chip-to-chip variations in
    // offset and LSB have to be calibrated, and they have 5% variations.
    // This is not done, because the display is a gross mesurement.
    // The code is designed so the failure voltage can be calibrated.
    return (3300L + (int32_t)((-2.298e-3) * (float)((v - 0x69D800L))));
}


/***************************************************************************
 * History
 * $Log: battest.c,v $
 * Revision 1.9  2006/09/27 01:34:19  tvander
 * Battery mode moved to DIO-8
 *
 * Revision 1.8  2006/09/12 02:44:49  gmikef
 * *** empty log message ***
 *
 * Revision 1.7  2006/08/09 00:57:33  tvander
 * *** empty log message ***
 *
 * Revision 1.6  2006/07/07 01:04:19  tvander
 * Only reports a battery error when there's supposed to be a battery.
 *
 * Revision 1.5  2006/06/14 02:41:26  tvander
 * New, derated battery test runs at 1/8 MPU speed, but uses 150x more battery
 * current.
 *
 * Revision 1.4  2006/06/06 03:57:33  tvander
 * Modified to run with hardware timers as well as software timers.
 *
 * Revision 1.3  2006/05/30 17:18:49  tvander
 * Made it possible to compile this on non-6520s
 *
 * Revision 1.2  2006/05/18 23:18:50  tvander
 * 16K and 32K
 * First cut at new requirements.
 * 32K 6521 is grossly tested.
 * All others have a clean compile with C51 8.02
 *
 * Revision 1.1  2006/05/17 19:07:59  tvander
 * Battery test works.
 * Power factor works for instantaneous value.  Periodic value compiles, but is
 * untested.
 *
 *
 * Copyright (C) 2005 Teridian Semiconductor Corp. All Rights Reserved.    *
 * this program is fully protected by the United States copyright          *
 * laws and is the property of Teridian Semiconductor Corporation.         *
 ***************************************************************************/
/* battest.c */
#endif // BATTERY_TEST