aon_batmon.c

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/******************************************************************************
*  Filename:       aon_batmon.c
*  Revised:        2015-10-21 16:28:04 +0200 (Wed, 21 Oct 2015)
*  Revision:       44798
*
*  Description:    Driver for the AON Battery and Temperature Monitor
*
*  Copyright (c) 2015, Texas Instruments Incorporated
*  All rights reserved.
*
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*  modification, are permitted provided that the following conditions are met:
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*
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*
*  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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******************************************************************************/

#include <driverlib/aon_batmon.h>
#include <inc/hw_fcfg1.h>

//*****************************************************************************
// Need to know the AON_BATMON:TEMP.INT field width in order to sign extend correctly
// (This is not given in the hw_aon_batmon.h file and therefore hard coded here)
//*****************************************************************************
#define AON_BATMON_TEMP_INT_FIELD_WIDTH   9
//*****************************************************************************
//
// AONBatMonTemperatureGetDegC()
// Returns sign extended temperature in Deg C (-256 .. +255)
//
//*****************************************************************************
int32_t
AONBatMonTemperatureGetDegC( void )
{
   int32_t  signedTemp        ; // Signed extended temperature with 8 fractional bits
   int32_t  tempCorrection    ; // Voltage dependent temp correction with 8 fractional bits
   int8_t   voltageSlope      ; // Signed byte value representing the TEMP slope with battery voltage, in degrees C/V, with 4 fractional bits.

   //
   // Shift left then right to sign extend the BATMON_TEMP field
   //
   signedTemp = ((((int32_t)HWREG( AON_BATMON_BASE + AON_BATMON_O_TEMP ))
     << ( 32 - AON_BATMON_TEMP_INT_FIELD_WIDTH - AON_BATMON_TEMP_INT_S ))
     >> ( 32 - AON_BATMON_TEMP_INT_FIELD_WIDTH - AON_BATMON_TEMP_INT_S ));

   //
   // Typecasting voltageSlope to int8_t prior to assignment in order to make sure sign extension works properly
   // Using byte read (HWREGB) in order to make more efficient code since voltageSlope is assigned to bits[7:0] of FCFG1_O_MISC_TRIM
   //
   voltageSlope      = ((int8_t)HWREGB( FCFG1_BASE + FCFG1_O_MISC_TRIM ));
   tempCorrection    = (( voltageSlope * (((int32_t)HWREG( AON_BATMON_BASE + AON_BATMON_O_BAT )) - 0x300 )) >> 4 );

   return ((( signedTemp - tempCorrection ) + 0x80 ) >> 8 );
}


// See aon_batmon.h for implementation of remaining functions