git.gag.com Git - debian/cc1111/blob - device/examples/ds390/i2c390/ds1621.c

   1 #include <tinibios.h>
   2
   3 #include "ds1621.h"
   4
   5 float ReadDS1621(char address) {
   6   float temperature;
   7   signed char counter, slope;
   8
   9   int id=DS1621_ID + (address<<1);
  10
  11   while (!I2CReset()) {
  12     //fprintf (stderr, "I2C bus busy, retrying.\n");
  13   }
  14
  15   i2cTransmitBuffer[0]=0xac; // access config command
  16   i2cTransmitBuffer[1]=0x09; // mode (8=continuous, 9=one-shot)
  17   if (I2CSend(id, 2)) return -999;
  18
  19   i2cTransmitBuffer[0]=0xee; // start conversion command
  20   if (I2CSend(id, 1)) return -999;
  21
  22   do {
  23     i2cTransmitBuffer[0]=0xac; // access config command
  24     if (I2CSendReceive(id, 1, 1)) return -999;
  25   } while ((i2cReceiveBuffer[0]&0x80)==0); // wait for conversion done
  26
  27   i2cTransmitBuffer[0]=0xaa; // read temperature command
  28
  29   if (I2CSendReceive(id, 1, 1)) return -999;
  30   temperature=i2cReceiveBuffer[0];
  31   i2cTransmitBuffer[0]=0xa8; // read counter command
  32   if (I2CSendReceive(id, 1, 1)) return -999;
  33   counter=i2cReceiveBuffer[0];
  34
  35   i2cTransmitBuffer[0]=0xa9; // read slope command
  36   if (I2CSendReceive(id, 1, 1)) return -999;
  37   slope=i2cReceiveBuffer[0];
  38
  39   temperature=temperature - 0.25 +
  40     ((float)slope-(float)counter)/(float)slope;
  41   return temperature;
  42 }