SCP1000 Drucksensor Problem - Gibt bei höherem Luftdruck einen niedrigeren Wert aus

//Pins definieren, werden durchgängig mit diesen Namen benutzt

#define SLAVESELECT 10

#define SPICLOCK 13

#define DATAOUT 11  //MOSI

#define DATAIN 12   //MISO

#define UBLB(a,b)  ( ( (a) << 8) | (b) )

#define UBLB19(a,b) ( ( (a) << 16 ) | (b) )

//Register Adressen

#define REVID 0x00  //ASIC Revision Nummer

#define OPSTATUS 0x04   //Operation Status

#define STATUS 0x07     //ASIC Status

#define START 0x0A      //Konstante Leserate

#define PRESSURE 0x1F   //Druck 3 MSB

#define PRESSURE_LSB 0x20 //Druck 16 LSB

#define TEMP 0x21       //16 bit Temperaut

char rev_in_byte;      

int temp_in;

unsigned long pressure_lsb;

unsigned long pressure_msb;

unsigned long temp_pressure;

unsigned long pressure;

void setup()

{

  byte clr;

  pinMode(DATAOUT, OUTPUT);

  pinMode(DATAIN, INPUT);

  pinMode(SPICLOCK,OUTPUT);

  pinMode(SLAVESELECT,OUTPUT);

  digitalWrite(SLAVESELECT,HIGH); //Sensor ausschalten und neue Konfiguration übernehmen

  SPCR = B01010011; //MPIE=0, SPE=1 (on), DORD=0 (MSB first), MSTR=1 (master), CPOL=0 (clock idle when low), CPHA=0 (samples MOSI on rising edge), SPR1=0 & SPR0=0 (500kHz)

  clr=SPSR;

  clr=SPDR;

  delay(10);

  Serial.begin(9600);

  delay(500);

  Serial.println("Initialisiere hohe Leserate");

  write_register(0x03,0x09);

}

void loop()

{

  rev_in_byte = read_register(REVID);

  pressure_msb = read_register(PRESSURE);

  pressure_msb &= B00000111;

  pressure_lsb = read_register16(PRESSURE_LSB);

  pressure_lsb &= 0x0000FFFF;

  pressure = UBLB19(pressure_msb, pressure_lsb);

  pressure /= 4;

  Serial.print("Druck in Pascal [");

  Serial.print(pressure, DEC);  

  Serial.print(" P");

  Serial.print("");

  Serial.println("]");

  Serial.print("Druck in Hekto-Pascal [");

  Serial.print(pressure/100, DEC);

  Serial.print(" hPa");

  Serial.print("");

  Serial.println("]");

  temp_in = read_register16(TEMP);

  temp_in = temp_in / 20;

  Serial.print("Temperatur in Grad Celcius [");     //Direkte Ausgabe

  Serial.print(temp_in , DEC);

  Serial.println("]");

  Serial.println("");

  delay(1500);

}

char spi_transfer(volatile char data)

{

  SPDR = data;        // SPDR auf Datenübergabe vorbereiten

  while (!(SPSR & (1<<SPIF)))     // Solange warten bis alle Bytes übertrage wurden

  {

  };

  return SPDR;        // return the received byte

}

char read_register(char register_name)

{

    char in_byte;

    register_name <<= 2;

    register_name &= B11111100; //Register lesen

    digitalWrite(SLAVESELECT,LOW); //SPI auswählen

    spi_transfer(register_name); //Datenbyte "in" SPI schreiben

    in_byte = spi_transfer(0x00); //Nichts senden. Gibt Register-Variable aus

    digitalWrite(SLAVESELECT,HIGH);

    delay(10);

    return(in_byte);

}

float read_register16(char register_name)

{

    byte in_byte1;

    byte in_byte2;

    float in_word;

    register_name <<= 2;

    register_name &= B11111100; //Register lesen

    digitalWrite(SLAVESELECT,LOW); //SPI auswählen

    spi_transfer(register_name); //Datenbyte "in" SPI schreiben

    in_byte1 = spi_transfer(0x00);    

    in_byte2 = spi_transfer(0x00);

    digitalWrite(SLAVESELECT,HIGH);

    in_word = UBLB(in_byte1,in_byte2);

    return(in_word);

}

void write_register(char register_name, char register_value)

{

    register_name <<= 2;

    register_name |= B00000010; //Register lsen

    digitalWrite(SLAVESELECT,LOW); //Datenbyte "in" SPI schreiben

    spi_transfer(register_name); //Send register location

    spi_transfer(register_value); //Send value to record into register

    digitalWrite(SLAVESELECT,HIGH);

}