fix: Restored DS18S20 support

Author: milesburton

DallasTemperature.cpp

@@ -36,6 +36,10 @@ extern "C" {
 
 #define NO_ALARM_HANDLER ((AlarmHandler *)0)
 
+// DSROM FIELDS
+#define DSROM_FAMILY 0
+#define DSROM_CRC 7
+
 DallasTemperature::DallasTemperature() {
  _wire = nullptr;
  devices = 0;
@@ -554,6 +558,37 @@ int32_t DallasTemperature::calculateTemperature(const uint8_t* deviceAddress, ui
  | neg;
  }
 
+ /*
+ DS1820 and DS18S20 have a 9-bit temperature register.
+
+ Resolutions greater than 9-bit can be calculated using the data from
+ the temperature, and COUNT REMAIN and COUNT PER °C registers in the
+ scratchpad. The resolution of the calculation depends on the model.
+
+ While the COUNT PER °C register is hard-wired to 16 (10h) in a
+ DS18S20, it changes with temperature in DS1820.
+
+ After reading the scratchpad, the TEMP_READ value is obtained by
+ truncating the 0.5°C bit (bit 0) from the temperature data. The
+ extended resolution temperature can then be calculated using the
+ following equation:
+
+ COUNT_PER_C - COUNT_REMAIN
+ TEMPERATURE = TEMP_READ - 0.25 + --------------------------
+ COUNT_PER_C
+
+ Hagai Shatz simplified this to integer arithmetic for a 12 bits
+ value for a DS18S20, and James Cameron added legacy DS1820 support.
+
+ See - http://myarduinotoy.blogspot.co.uk/2013/02/12bit-result-from-ds18s20.html
+ */
+ 
+ if ((deviceAddress[DSROM_FAMILY] == DS18S20MODEL) && (scratchPad[COUNT_PER_C] != 0)) {
+ fpTemperature = (((fpTemperature & 0xfff0) << 3) - 32
+ + (((scratchPad[COUNT_PER_C] - scratchPad[COUNT_REMAIN]) << 7)
+ / scratchPad[COUNT_PER_C])) | neg;
+ }
+
  return fpTemperature;
 }
 

DallasTemperature.h

@@ -1,7 +1,7 @@
 #ifndef DallasTemperature_h
 #define DallasTemperature_h
 
-#define DALLASTEMPLIBVERSION "4.0.1"
+#define DALLASTEMPLIBVERSION "4.0.2"
 
 // Configuration
 #ifndef REQUIRESNEW

library.json

@@ -32,7 +32,7 @@
  {
  "paulstoffregen/OneWire": "^2.3.5"
  },
- "version": "4.0.1",
+ "version": "4.0.2",
  "frameworks": "arduino",
  "platforms": "*"
 }

library.properties

@@ -1,5 +1,5 @@
 name=DallasTemperature
-version=4.0.1
+version=4.0.2
 author=Miles Burton <mail@milesburton.com>, Tim Newsome <nuisance@casualhacker.net>, Guil Barros <gfbarros@bappos.com>, Rob Tillaart <rob.tillaart@gmail.com>
 maintainer=Miles Burton <mail@milesburton.com>
 sentence=Arduino library for Dallas/Maxim temperature ICs