testtemp.c

/******************************************************************************

*

*  AVR Code example to read a TSIC-206 / TSIC-306 digital temperatur probe

*

*  Based on C++ Samplecode in 

*  "Tech Notes - ZACwireTM Digital Output, Rev. 2.3, October 17, 2006"

*

*  Tested with ATMega8, avr-gcc (GCC) 4.3.0 and a TSIC-206

*

*  see also discussion at http://www.mikrocontroller.net/topic/82087

*

******************************************************************************/

#define F_CPU 8000000UL    // Clock of target system

#include <avr/io.h>

#include <util/delay.h>

/******************************************************************************

* Hardware Connection of the TSIC-Sensor

******************************************************************************/

#define TSIC_PORT             PORTD  // Port to use

#define TSIC_PIN              PIND

#define TSIC_PORT_DDR         DDRD

#define TSCI_POWER_PIN        PD6    // Where TSIC-Sensors VCC is connected

#define TSIC_SIGNAL_PIN       PD7    // Where TSIC-Sensors "Signal"-Pin is con.

/******************************************************************************

* FUNCTION MACROS

******************************************************************************/

// Define TSCI_POWER_PIN as output, TSIC_SIGNAL_PIN as input

#define TSIC_INIT()           { TSIC_PORT_DDR |= (1<<TSCI_POWER_PIN); \

                              TSIC_PORT_DDR &= ~(1<<TSIC_SIGNAL_PIN); }

// Power up the TSIC-Sensor

#define TSIC_ON()             TSIC_PORT |=  (1<<TSCI_POWER_PIN)

// Power down the TSIC-Sensor

#define TSIC_OFF()            TSIC_PORT &= ~(1<<TSCI_POWER_PIN)

//#define TSIC_SIGNAL           (TSIC_PORT &   (1<<TSIC_SIGNAL_PIN))

// Low/High Signal of the TSIC-Sensor, e.g. "if(TSIC_SIGNAL_HIGH)..."

#define TSIC_SIGNAL_HIGH      TSIC_PIN & ( 1 << TSIC_SIGNAL_PIN )

#define TSIC_SIGNAL_LOW       !( TSIC_PIN & ( 1 << TSIC_SIGNAL_PIN ))

/******************************************************************************

* Function    :   getTSicTemp(*temp_value16);

* Description :   reads from the TSic its output value

* Parameters  :   pointer for return value

* Returns     :   1: reading sucessfull, 0: parity error

******************************************************************************/

uint8_t getTSicTemp (uint16_t *temp_value16) {

  uint16_t temp_value1 = 0;

  uint16_t temp_value2 = 0;

  uint8_t i;

  uint16_t Temperature;

  uint8_t parity;

  TSIC_ON();

  _delay_us(60);  // wait for stabilization

  _delay_us(60);

  while (TSIC_SIGNAL_HIGH); // wait until start bit starts

  // wait, TStrobe

  while (TSIC_SIGNAL_LOW);

  // first data byte

  // read 8 data bits and 1 parity bit

  for (i = 0; i < 9; i++) {

    while (TSIC_SIGNAL_HIGH);              // wait for falling edge

    _delay_us(60);

    if (TSIC_SIGNAL_HIGH)

        temp_value1 |= 1 << (8-i);         // get the bit

      else

        while (TSIC_SIGNAL_LOW);           // wait until line comes high again

  }

  // second byte

  while (TSIC_SIGNAL_HIGH);

  // wait, TStrobe

  while (TSIC_SIGNAL_LOW);

  // read 8 data bits and 1 parity bit

  for (i = 0; i < 9; i++) {

    while (TSIC_SIGNAL_HIGH);               // wait for falling edge

    _delay_us(60);

    if (TSIC_SIGNAL_HIGH)

        temp_value2 |= 1 << (8-i);          // get the bit

      else

        while (TSIC_SIGNAL_LOW);            // wait until line comes high again

  }

  TSIC_OFF();                               // switch TSic off

  // check parity for byte 1

  parity = 0;

  for (i = 0; i < 9; i++)

    if (temp_value1 & (1 << i))

        parity++;

  if (parity % 2)

  return 0;

  // check parity for byte 2

  parity = 0;

  for (i = 0; i < 9; i++)

    if (temp_value2 & (1 << i))

        parity++;

  if (parity % 2)

        return 0;

  temp_value1 >>= 1;                 // delete parity bit

  temp_value2 >>= 1;                 // delete parity bit

  Temperature = (temp_value1 << 8) | temp_value2;

  *temp_value16 = Temperature;

  return 1;                       // parity is OK

}

void ItoA( int z, char* Buffer )

{

  int i = 0;

  int j;

  char tmp;

  unsigned u;    // In u bearbeiten wir den Absolutbetrag von z.

    // ist die Zahl negativ?

    // gleich mal ein - hinterlassen und die Zahl positiv machen

    if( z < 0 ) {

      Buffer[0] = '-';

      Buffer++;

      // -INT_MIN ist idR. größer als INT_MAX und nicht mehr 

      // als int darstellbar! Man muss daher bei der Bildung 

      // des Absolutbetrages aufpassen.

      u = ( (unsigned)-(z+1) ) + 1; 

    }

    else { 

      u = (unsigned)z;

    }

    // die einzelnen Stellen der Zahl berechnen

    do {

      Buffer[i++] = '0' + u % 10;

      u /= 10;

    } while( u > 0 );

    // den String in sich spiegeln

    for( j = 0; j < i / 2; ++j ) {

      tmp = Buffer[j];

      Buffer[j] = Buffer[i-j-1];

      Buffer[i-j-1] = tmp;

    }

    Buffer[i] = '\0';

}

/******************************************************************************

* Test application

******************************************************************************/

int main (void) {

  uint16_t temperatur;  // 11-bit temperature value

  uint8_t returnvalue;  // return value of getTSicTemp(*temp);

  uint8_t Temp_celsius; // converted temperature in °C

  TSIC_INIT();          // set data direction of IO-Pins

  char asdf[20];

  while(1){

    returnvalue = getTSicTemp(&temperatur);  // pull the TSIC-Sensor

    // conversion equation from TSic's data sheet

    Temp_celsius = ((float)temperatur / 2047 * 200) - 50;

    // DO SOMETHING USEFUL WITH THE VALUES HERE!

    // e.g. display them ;)

  if(returnvalue==1){

    ItoA(Temp_celsius,asdf);

    }

  }

}