(2016)
*
* hdc_raw_to_celcius.php --
*
* This is the backend tool for converting raw HDC sensor data
* into its proper celcius temperature reading.
*/
$scriptName="hdc_raw_to_celcius.php";
$version="0.2.2";
print ("Script name is $scriptName and version is $version
");
/* Function to convert raw HDC10xx ambient temp hex string into celcius temperature.
* Example calls: $chk_amb_temp = hex2temperature(substr($mood_key,20,4));
* Takes raw mood_key sensor data; converts LSB and MSB order; converts to binary;
* right shifts by 2 bits; and divides by 32 to arrive at degrees C value.
*
* Calls to function made as follows for examaple:
* http://serverIP/hdc_raw_to_celcius.php?rawValue=205C
*/
function hex2temperature($hex) {
$hex = strtoupper($hex);
$temperature = 0;
$LSBhex = substr($hex,0,2); // Isolate raw hex string
$MSBhex = substr($hex,2,2);
echo "
LSB value is ".$LSBhex."
";
echo "
MSB value is ".$MSBhex."
";
$MSBLSB = $MSBhex.$LSBhex;
echo "
Converted hex string before binary conversion is ".$MSBLSB."
";
echo "
Original raw hex string value was ".$hex."
";
$hexInBinary = "";
For ($i=0; $i <= (strlen($hex)-1); $i++) {
$hexDigit = substr($hex,$i,1);
switch ($hexDigit):
case '0':
$hexInBinary = $hexInBinary."0000";
break;
case '1':
$hexInBinary = $hexInBinary."0001";
break;
case '2':
$hexInBinary = $hexInBinary."0010";
break;
case '3':
$hexInBinary = $hexInBinary."0011";
break;
case '4':
$hexInBinary = $hexInBinary."0100";
break;
case '5':
$hexInBinary = $hexInBinary."0101";
break;
case '6':
$hexInBinary = $hexInBinary."0110";
break;
case '7':
$hexInBinary = $hexInBinary."0111";
break;
case '8':
$hexInBinary = $hexInBinary."1000";
break;
case '9':
$hexInBinary = $hexInBinary."1001";
break;
case 'A':
$hexInBinary = $hexInBinary."1010";
break;
case 'B':
$hexInBinary = $hexInBinary."1011";
break;
case 'C':
$hexInBinary = $hexInBinary."1100";
break;
case 'D':
$hexInBinary = $hexInBinary."1101";
break;
case 'E':
$hexInBinary = $hexInBinary."1110";
break;
case 'F':
$hexInBinary = $hexInBinary."1111";
break;
endswitch;
}
echo "
Manually converted hex to binary string is ".$hexInBinary."
";
$revString = "";
//$hex = double(base_convert($hex, 16, 2));
echo "
Binary version of original raw data before reversing is ".$hexInBinary."
";
$unsignedDec = 0;
For ($i=0; $i <= (strlen($hexInBinary)-1); $i++) {
$revString = substr($hexInBinary,$i,1).$revString;
if (substr($hexInBinary,$i,1) == "1"){$unsignedDec = $unsignedDec + pow(2,$i);}
}
echo "
Reversed binary version of raw submitted data is ".$revString."
";
echo "
Unsigned decimal value of reversed binary string is ".$unsignedDec."
";
//$rawTempBin = base_convert($MSBLSB, 16, 2);
//echo "
Binary version of raw data in corrected order before shifting is ".$rawTempBin."
";
//echo "
Binary version of raw data in original format is ".base_convert($hex, 16, 2)."
";
//$rawTempBinShift = substr($rawTempBin, 0, strlen($rawTempBin)-2);
//echo "
Binary value after right shift by 2 is ".$rawTempBinShift."
";
$rawTempDec = ($unsignedDec); // Converted reversed binary to decimal
//$rawTempDec = base_convert($revString, 2, 10); // Convert from original binary to decimal
$temperature = (($rawTempDec/65536)*165 - 40); // Calculate celcius value
return $temperature;
}
// End of hex2temperature function
echo "
";
///////////////////////////////////////////////////////////
$rawValue = $_GET['rawValue'];
$rawValue = trim($rawValue);
$result = hex2temperature($rawValue);
echo "01: The raw hex string value to be converted to celcius is the following:
";
echo $rawValue;
echo "
";
echo "02: The corresponding celcius value is the following:
";
echo $result;
echo "";
echo "
";
///////////////////////////////////////////////////////////
//End of hdc_raw_to_celcius
?>