Rob Dobson / RdGasUseMonitor

Monitor for central heating system (e.g. 2zones+hw) Supports up to 15 temp probes (DS18B20/DS18S20) 3 valve monitors Gas pulse meter recording Use stand-alone or with nodeEnergyServer See http://robdobson.com/2015/09/central-heating-monitor

Dependencies:   EthernetInterfacePlusHostname NTPClient Onewire RdWebServer SDFileSystem-RTOS mbed-rtos mbed-src

Diff: RdDS18B20.cpp

Revision:
13:9ec0e11cf3c1
Parent:
10:72eb217def1f
Child:
16:89778849e9f7
--- a/RdDS18B20.cpp	Sun Feb 22 22:08:37 2015 +0000
+++ b/RdDS18B20.cpp	Sun Feb 22 22:33:25 2015 +0000
@@ -43,7 +43,7 @@
     _oneWire.writeByte(0xBE);
 
     // Temperature val
-    int temperatureVals[] = {0,0};
+    unsigned char temperatureVals[9];
 
     // Read values back
     for (int i = 0; i < sizeof(temperatureVals)/sizeof(int); i++)
@@ -52,8 +52,33 @@
     }
     _oneWire.init();
     
+    // Check the CRC
+    if (_oneWire.CRC(temperatureVals, sizeof(temperatureVals)/sizeof(int)-1) == temperatureVals[sizeof(temperatureVals)/sizeof(int)-1])
+    {
+#ifdef SHOW_18B20_DEBUGGING
+        printf("Temp CRC Fail\r\n");
+#endif
+        return INVALID_TEMPERATURE;
+    }
+    else
+    {
+#ifdef SHOW_18B20_DEBUGGING
+        double temperature = ((((int)(temperatureVals[1])) * 256) + temperatureVals[0])*0.0625;
+        printf("Temp = %0.1f", temperature);
+#endif
+    }
+    
     // Convert temperature
-    double temperature = ((temperatureVals[1] * 256) + temperatureVals[0])*0.0625;
+    double temperature = ((((int)(temperatureVals[1])) * 256) + temperatureVals[0])*0.0625;
+    
+    // Do a bounds check
+    if ((temperature < -10) || (temperature > 100))
+    {
+#ifdef SHOW_18B20_DEBUGGING
+        printf("Temp out of bounds\r\n");
+#endif
+        return INVALID_TEMPERATURE;
+    }
     _temperatureTable[addrIdx] = temperature;
     _timeOfReadingTable[addrIdx] = time(NULL);
     return temperature;