Add strong pull-up for parasitic power

Not 100% sure this is exactly the right timing for these commands, but
it works.

Was unable to read more than 3 sensors unless doing it very slowly
before.

OneWire.cpp

@@ -98,6 +98,16 @@ uint8_t OneWire::readConfig()
 	return readByte();
 }
 
+void OneWire::setStrongPullup()
+{
+	writeConfig(readConfig() | DS2482_CONFIG_SPU);
+}
+
+void OneWire::clearStrongPullup()
+{
+	writeConfig(readConfig() & !DS2482_CONFIG_SPU);
+}
+
 // Churn until the busy bit in the status register is clear
 uint8_t OneWire::waitOnBusy()
 {
@@ -140,6 +150,11 @@ void OneWire::writeConfig(uint8_t config)
 uint8_t OneWire::wireReset()
 {
 	waitOnBusy();
+	// Datasheet warns that reset with SPU set can exceed max ratings
+	clearStrongPullup();
+
+	waitOnBusy();
+
 	begin();
 	writeByte(DS2482_COMMAND_RESETWIRE);
 	end();
@@ -155,9 +170,11 @@ uint8_t OneWire::wireReset()
 }
 
 // Writes a single data byte to the 1-Wire line.
-void OneWire::wireWriteByte(uint8_t data)
+void OneWire::wireWriteByte(uint8_t data, uint8_t power)
 {
 	waitOnBusy();
+	if (power)
+		setStrongPullup();
 	begin();
 	writeByte(DS2482_COMMAND_WRITEBYTE);
 	writeByte(data);
@@ -179,9 +196,11 @@ uint8_t OneWire::wireReadByte()
 // (see Table 2). A V value of 0b generates a write-zero time slot (Figure 5); a V value of 1b generates a 
 // write-one time slot, which also functions as a read-data time slot (Figure 6). In either case, the logic
 // level at the 1-Wire line is tested at tMSR and SBR is updated.
-void OneWire::wireWriteBit(uint8_t data)
+void OneWire::wireWriteBit(uint8_t data, uint8_t power)
 {
 	waitOnBusy();
+	if (power)
+		setStrongPullup();
 	begin();
 	writeByte(DS2482_COMMAND_SINGLEBIT);
 	writeByte(data ? 0x80 : 0x00);
@@ -389,7 +408,7 @@ void OneWire::skip(void)
 // Ignore the power bit
 void OneWire::write(uint8_t v, uint8_t power)
 {
-	wireWriteByte(v);	
+	wireWriteByte(v, power);	
 }
 
 // Read a byte.

OneWire.h

@@ -21,6 +21,10 @@
 		#define DS2482_STATUS_DIR 			(1<<7)
 	#define DS2482_POINTER_DATA			0xE1
 	#define DS2482_POINTER_CONFIG		0xC3
+		#define DS2482_CONFIG_APU			(1<<0)
+		#define DS2482_CONFIG_SPU			(1<<2)
+		#define DS2482_CONFIG_1WS			(1<<3)
+
 
 #define DS2482_COMMAND_WRITECONFIG	0xD2
 #define DS2482_COMMAND_RESETWIRE	0xB4
@@ -54,10 +58,12 @@ class OneWire
 	uint8_t waitOnBusy();
 	uint8_t readConfig();
 	void writeConfig(uint8_t config);
+	void setStrongPullup();
+	void clearStrongPullup();
 	uint8_t wireReset();
-	void wireWriteByte(uint8_t data);
+	void wireWriteByte(uint8_t data, uint8_t power = 0);
 	uint8_t wireReadByte();
-	void wireWriteBit(uint8_t data);
+	void wireWriteBit(uint8_t data, uint8_t power = 0);
 	uint8_t wireReadBit();
 	void wireSkip();
 	void wireSelect(const uint8_t rom[8]);