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   1 #include "i2clole.h"
   2 #include "ds1621.h"
   3
   4 #if USE_FLOAT // defined in ds1621.h
   5 static float temperature
   6 signed char counter, slope;
   7 float
   8 #else
   9 #include <stdio.h>
  10 static char temperature[10];
  11 char *
  12 #endif
  13
  14 ReadDS1621(char address) {
  15   int id=DS1621_ID + (address<<1);
  16
  17   while (!I2CReset()) {
  18     //fprintf (stderr, "I2C bus busy, retrying.\n");
  19   }
  20
  21   i2cTransmitBuffer[0]=0xac; // access config command
  22   i2cTransmitBuffer[1]=0x09; // mode (8=continuous, 9=one-shot)
  23   if (I2CSend(id, 2)) return -999;
  24
  25   i2cTransmitBuffer[0]=0xee; // start conversion command
  26   if (I2CSend(id, 1)) return -999;
  27
  28   do {
  29     i2cTransmitBuffer[0]=0xac; // access config command
  30     if (I2CSendReceive(id, 1, 1)) return -999;
  31   } while ((i2cReceiveBuffer[0]&0x80)==0); // wait for conversion done
  32
  33
  34   // if we did not do this, sdcc thinks i2cReceiveBuffer[0] is still in r3
  35   i2cReceiveBuffer[0]=0;
  36
  37   i2cTransmitBuffer[0]=0xaa; // read temperature command
  38
  39 #if !USE_FLOAT
  40   if (I2CSendReceive(id, 1, 2)) return -999;
  41   sprintf (temperature, "% 3bd.%c", i2cReceiveBuffer[0],
  42            i2cReceiveBuffer[1]?'5':'0');
  43   return temperature;
  44 #else
  45   if (I2CSendReceive(id, 1, 1)) return -999;
  46   temperature=i2cReceiveBuffer[0];
  47   i2cTransmitBuffer[0]=0xa8; // read counter command
  48   if (I2CSendReceive(id, 1, 1)) return -999;
  49   counter=i2cReceiveBuffer[0];
  50
  51   i2cTransmitBuffer[0]=0xa9; // read slope command
  52   if (I2CSendReceive(id, 1, 1)) return -999;
  53   slope=i2cReceiveBuffer[0];
  54
  55   temperature=(int)temperature - 0.25 +
  56     ((float)slope-(float)counter)/(float)slope;
  57     return temperature;
  58 #endif
  59 }
  60