Merge https://github.com/milesburton/Arduino-Temperature-Control-Library

Author: RobTillaart

DallasTemperature.cpp

@@ -152,7 +152,7 @@ bool DallasTemperature::isConnected(const uint8_t* deviceAddress) {
 bool DallasTemperature::isConnected(const uint8_t* deviceAddress,
 		uint8_t* scratchPad) {
 	bool b = readScratchPad(deviceAddress, scratchPad);
-	return b && (_wire->crc8(scratchPad, 8) == scratchPad[SCRATCHPAD_CRC]);
+	return b && !isAllZeros(scratchPad) && (_wire->crc8(scratchPad, 8) == scratchPad[SCRATCHPAD_CRC]);
 }
 
 bool DallasTemperature::readScratchPad(const uint8_t* deviceAddress,
@@ -614,6 +614,17 @@ float DallasTemperature::rawToFahrenheit(int16_t raw) {
 
 }
 
+// Returns true if all bytes of scratchPad are '\0'
+bool DallasTemperature::isAllZeros(const uint8_t * const scratchPad, const size_t length) {
+	for (size_t i = 0; i < length; i++) {
+		if (scratchPad[i] != 0) {
+			return false;
+		}
+	}
+
+	return true;
+}
+
 #if REQUIRESALARMS
 
 /*

DallasTemperature.h

@@ -239,6 +239,9 @@ class DallasTemperature {
 
 	void blockTillConversionComplete(uint8_t);
 
+	// Returns true if all bytes of scratchPad are '\0'
+	bool isAllZeros(const uint8_t* const scratchPad, const size_t length = 9);
+
 #if REQUIRESALARMS
 
 	// required for alarmSearch