gas_mon.c

DS2438 one wire (ow) battery monitor code for renesas M16c... (-:cool:-)

    writebyte(READ_ROM); // read ROM
    
    //read family code and discard
    readbyte();

    monitor_id.asbytes.lowbyte = readbyte(); // read first byte of ID
    monitor_id.asbytes.highbyte = readbyte(); // read second byte of ID

    // to do:  read all 4 bytes of ID
  
    // terminate read sequence since we don't want anything else

    // to do: read more bytes
     

    asm("fset I");  // enable interrupts    


    return (monitor_id.asword);
}


//_____________________________________________________________________________
//  gas_mon_readTemp
//_____________________________________________________________________________
// read the Temperature
// Units: degrees Celsius
//_____________________________________________________________________________
float gas_mon_readTemp(void)
{
    word_union temperature;
    int this_reading;
    double accumulatedTemperature = 0;

    asm("fclr I");  // disable interrupts 

    for(this_reading = 0; this_reading < MON_TEMP_READINGS_TO_AVERAGE ; this_reading++)
    {
        // start temp conversion
        resetDQ(); // modify to check for presence pulse was received OK
        writebyte(SKIP_ROM); // Skip ROM
        writebyte(CONVERT_T); // start conversion
        while (!readBit()); // the monitor outputs all zeros on the DQ line
                                // until the conversion is complete, at which
                                // time it outputs all ones.
        //recall page 0 to scratchpad
        resetDQ(); 
        writebyte(SKIP_ROM); // Skip ROM
        writebyte(RECALL_MEMORY); // recall SP command
        writebyte(0x00); // page number to read
    
    
        //read scratchpad
        resetDQ(); 
        writebyte(SKIP_ROM); // Skip ROM
        writebyte(READ_SP); // read SP command
        writebyte(0); // page number to read
        readbyte(); // throw away first byte
        temperature.asbytes.lowbyte = readbyte(); // read LSB of temperature
        temperature.asbytes.highbyte= readbyte(); // read MSB of temperature
         
        // convert from 13 bit signed int where each count represents 0.03125 degrees
        // Celsius.  The last 3 bits are always 000.  
        // 11001001 00000000 = 0xC900 = -55.0000 degrees Celsius
        // MSB is whole parts of degrees, MS bit is a sign bit
        // LSB is whole fractional parts of degrees
        // See page 4 of the DS2438 data sheet
    
        // terminate read sequence since we don't want anything else
    
        // to do: CRC check 
        accumulatedTemperature += (double)(temperature.asSignedInt)/256.0; // convert 
      
    }

    asm("fset I");  // enable interrupts    

    return (float)(accumulatedTemperature / MON_TEMP_READINGS_TO_AVERAGE )+getTempFromGasMonitorCalOffset();
}


//_____________________________________________________________________________
//  gas_mon_readCurrentRegisterword
//_____________________________________________________________________________
// N.B.:  If you have just set the IAD bit, you must wait 80ms to be safe that
//        the current A/D is operating and updating the current register before
//        calling this function.
// Read the current and return the actual content of the current register
// Units: mA
//_____________________________________________________________________________
word gas_mon_readCurrentRegisterword(void)
{
    word_union currentRegister;

    asm("fclr I");  // disable interrupts 

    
    //recall page 0 to scratchpad
    resetDQ(); 
    writebyte(SKIP_ROM); // Skip ROM
    writebyte(RECALL_MEMORY); // recall SP command
    writebyte(0x00); // page number to read


    //read scratchpad
    resetDQ(); 
    writebyte(SKIP_ROM); // Skip ROM
    writebyte(READ_SP); // read SP command
    writebyte(0x00); // page number to read
    readbyte(); // throw away these
    readbyte(); // throw away these
    readbyte(); // throw away these
    readbyte(); // throw away these
    readbyte(); // throw away these
    currentRegister.asbytes.lowbyte = readbyte(); // read LSB of current
    currentRegister.asbytes.highbyte = readbyte(); // read LSB of current

     

    asm("fset I");  // enable interrupts    

    // to do: add CRC check
    return currentRegister.asword;
}


//_____________________________________________________________________________
//  gas_mon_readCurrent
//_____________________________________________________________________________
// N.B.:  If you have just set the IAD bit, you must wait 80ms to be safe that
//        the current A/D is operating and updating the current register before
//        calling this function.
// Read the current and return a signed float indicating current magnitude
// and direction.  -ve means discharging, +ve means charging. Units: mA
//_____________________________________________________________________________
float gas_mon_readCurrent(void)
{
    word_union currentRegister;    
    
    currentRegister.asword = gas_mon_readCurrentRegisterword();
    
    // from signed int, convert to mA
    return (float)currentRegister.asSignedInt/(4096.0f*getGascellSenseResistor())*1000.0f; 
}


//_____________________________________________________________________________
//  gas_mon_readCurrentAbs
//_____________________________________________________________________________
// N.B.:  If you have just set the IAD bit, you must wait 80ms to be safe that
//        the current A/D is operating and updating the current register before
//        calling this function.
// read the current and take the absolute value of it
// will return +ve value both for charging and discharging
// Units: mA
//_____________________________________________________________________________
float gas_mon_readCurrentAbs(void)
{
    float signed_current;
    
    signed_current = gas_mon_readCurrent();
    return (signed_current > 0)? signed_current:-signed_current;
}


//_____________________________________________________________________________
//  gas_mon_readICA
//_____________________________________________________________________________
// Read the integrating current accumulator
// Note:  The ICA counts DOWN when the gascell is discharging
// Units: mA*hours
//_____________________________________________________________________________
float gas_mon_readICA(void)
{
    byte ICA_register;

    ICA_register = gas_mon_readRegister(1, 4);  //  ICA register is byte 4 on page 1
    return(  ((float)ICA_register)/(2048.0f*getGascellSenseResistor())*1000.0f  ); // convert to mAhr
}


//_____________________________________________________________________________
//  gas_mon_readICA_Registerbyte
//_____________________________________________________________________________
// Read the integrating current accumulator
// Note:  The ICA counts DOWN when the gascell is discharging
// Returns the raw register value.
//_____________________________________________________________________________
byte gas_mon_readICA_Registerbyte(void)
{
    return gas_mon_readRegister(1, 4);  //  ICA register is byte 4 on page 1
}

//_____________________________________________________________________________
//  gas_mon_read_V_at_Vad_Pin
//_____________________________________________________________________________
// Note:  Vad means Vad pin on gascell monitor pin, not necessarily Vad
//        in the application.
//_____________________________________________________________________________
float gas_mon_read_V_at_Vad_Pin(void)
{
    gas_mon_changeToVad();    
    return gas_mon_readVoltage();
}



//_____________________________________________________________________________
//  gas_mon_read_V_at_Vdd_Pin
//_____________________________________________________________________________
// Note:  Vdd means Vdd pin on gascell monitor pin, not necessarily Vdd
//        in the application.
//_____________________________________________________________________________
float gas_mon_read_V_at_Vdd_Pin(void)
{
    gas_mon_changeToVdd();    
    return gas_mon_readVoltage();
}


//_____________________________________________________________________________
//  gas_mon_readRegister
//_____________________________________________________________________________
// reads a register given a register and page number
//_____________________________________________________________________________
byte gas_mon_readRegister(byte page, byte byteToRead)
{
    int i;

    asm("fclr I");  // disable interrupts 

    //recall page to scratchpad
    resetDQ(); 
    writebyte(SKIP_ROM); // Skip ROM
    writebyte(RECALL_MEMORY); // recall SP command
    writebyte(page); // page number to read
    
    //read scratchpad and discard all bytes before required one
    resetDQ(); 
    writebyte(SKIP_ROM); // Skip ROM
    writebyte(READ_SP); // read SP command
    writebyte(page); // page number to read
    for (i=0; i<byteToRead; i++)
    {
         readbyte(); // discard bytes until we get to the right one
    }
     

    asm("fset I");  // enable interrupts    

    return(readbyte());
}
    

//_____________________________________________________________________________
//  gas_mon_writeRegister
//_____________________________________________________________________________
// Writes a register to a given register and page number.
// First, all bytes up to the byte to be written are read and saved.
// This is because you can't write to a byte in the page except as part
// of a sequence of writing to bytes in that page starting from byte 0.
// The saved bytes are replayed when the page is re-written with the new byte.
//_____________________________________________________________________________
void gas_mon_writeRegister(byte page, byte byteToChange, byte data)
{
    int i;
    byte storedbytes[8];

    asm("fclr I");  // disable interrupts 
    
    //recall page to scratchpad
    resetDQ(); 
    writebyte(SKIP_ROM); // Skip ROM
    writebyte(RECALL_MEMORY); // recall SP command
    writebyte(page); // page number to read
    
    //read scratchpad and store all bytes before required one
    resetDQ(); 
    writebyte(SKIP_ROM); // Skip ROM
    writebyte(READ_SP); // read SP command
    writebyte(page); // page number to read

    for (i=0; i<byteToChange; i++)
    {
         storedbytes[i]=readbyte(); // store all bytes before the right one
    }
    
    //write to scratchpad page
    resetDQ(); 
    writebyte(SKIP_ROM); // Skip ROM
    writebyte(WRITE_SP); // write to scratch pad
    writebyte(page); // scratch pad 
    for (i=0; i<byteToChange; i++)
    {
         writebyte(storedbytes[i]); // write stored bytes until we get to the right one
    }

    writebyte(data); // write the given byte

    // don't bother writing the rest - just reset it
    resetDQ(); 
    
    //copy scratchpad page to memory
    writebyte(SKIP_ROM); // Skip ROM
    writebyte(COPY_SP); // copy scratch pad
    writebyte(page); // page number to copy
    while (!readBit()); // the monitor outputs all zeros on the DQ line
                            // until the NV writing is complete, at which
                  // time it outputs all ones.

    asm("fset I");  // enable interrupts    
}



//_____________________________________________________________________________
//  gas_mon_setIAD
//_____________________________________________________________________________
// IAD turns the current A/D on and off and must be off for performing some functions
// such as writing the threshold register.
// N.B.:  When you set the IAD bit, you must wait 80ms to be safe that
//        the current A/D is operating and updating the current register before
//        reading the current register.
//_____________________________________________________________________________
void gas_mon_setIAD(void)
{
    byte_union status_config_reg;
   
    status_config_reg.asbyte = gas_mon_readRegister(0, 0); 
    status_config_reg.asBits.b0 = 1;
    gas_mon_writeRegister(0, 0, status_config_reg.asbyte);
}


//_____________________________________________________________________________
//  gas_mon_clearIAD