- fix 145 - readPowerSupply extended + example added

Author: RobTillaart

DallasTemperature.cpp

@@ -233,17 +233,25 @@ void DallasTemperature::writeScratchPad(const uint8_t* deviceAddress,
 
 }
 
-bool DallasTemperature::readPowerSupply(const uint8_t* deviceAddress) {
-
-	bool ret = false;
+// returns true if parasite mode is used (2 wire)
+// returns false if normal mode is used (3 wire)
+// if no address is given (or nullptr) it checks if any device on the bus
+// uses parasite mode.
+// See issue #145
+bool DallasTemperature::readPowerSupply(const uint8_t* deviceAddress)
+{
+	bool parasiteMode = false;
 	_wire->reset();
-	_wire->select(deviceAddress);
+	if (deviceAddress == nullptr)
+		_wire->skip();
+	else
+		_wire->select(deviceAddress);
+
 	_wire->write(READPOWERSUPPLY);
 	if (_wire->read_bit() == 0)
-		ret = true;
+		parasiteMode = true;
 	_wire->reset();
-	return ret;
-
+	return parasiteMode;
 }
 
 // set resolution of all devices to 9, 10, 11, or 12 bits

DallasTemperature.h

@@ -1,7 +1,7 @@
 #ifndef DallasTemperature_h
 #define DallasTemperature_h
 
-#define DALLASTEMPLIBVERSION "3.7.9" // To be deprecated
+#define DALLASTEMPLIBVERSION "3.8.1" // To be deprecated -> TODO remove in 4.0.0
 
 // This library is free software; you can redistribute it and/or
 // modify it under the terms of the GNU Lesser General Public
@@ -37,6 +37,11 @@
 #define DEVICE_DISCONNECTED_F -196.6
 #define DEVICE_DISCONNECTED_RAW -7040
 
+// For readPowerSupply on oneWire bus
+#ifndef nullptr
+#define nullptr NULL
+#endif
+
 typedef uint8_t DeviceAddress[8];
 
 class DallasTemperature {
@@ -82,7 +87,7 @@ class DallasTemperature {
 	void writeScratchPad(const uint8_t*, const uint8_t*);
 
 	// read device's power requirements
-	bool readPowerSupply(const uint8_t*);
+	bool readPowerSupply(const uint8_t* deviceAddress = nullptr);
 
 	// get global resolution
 	uint8_t getResolution();

examples/readPowerSupply/readPowerSupply.ino

@@ -0,0 +1,92 @@
+//
+// FILE: readPowerSupply.ino
+// AUTHOR: Rob Tillaart
+// VERSION: 0.1.0
+// PURPOSE: demo
+// DATE: 2020-02-10
+//
+// Released to the public domain
+//
+
+// Include the libraries we need
+#include <OneWire.h>
+#include <DallasTemperature.h>
+
+// Data wire is plugged into port 2 on the Arduino
+#define ONE_WIRE_BUS 2
+
+// Setup a oneWire instance to communicate with any OneWire devices
+OneWire oneWire(ONE_WIRE_BUS);
+
+// Pass our oneWire reference to Dallas Temperature. 
+DallasTemperature sensors(&oneWire);
+
+// arrays to hold device addresses
+DeviceAddress insideThermometer, outsideThermometer;
+// Assign address manually. The addresses below will beed to be changed
+// to valid device addresses on your bus. Device address can be retrieved
+// by using either oneWire.search(deviceAddress) or individually via
+// sensors.getAddress(deviceAddress, index)
+// DeviceAddress insideThermometer = { 0x28, 0x1D, 0x39, 0x31, 0x2, 0x0, 0x0, 0xF0 };
+// DeviceAddress outsideThermometer   = { 0x28, 0x3F, 0x1C, 0x31, 0x2, 0x0, 0x0, 0x2 };
+
+int devCount = 0;
+
+/*
+ * The setup function. We only start the sensors here
+ */
+void setup(void)
+{
+  Serial.begin(115200);
+  Serial.println("Arduino Temperature Control Library Demo - readPowerSupply");
+
+  sensors.begin();
+
+  devCount = sensors.getDeviceCount();
+  Serial.print("#devices: ");
+  Serial.println(devCount);
+
+  // report parasite power requirements
+  Serial.print("Parasite power is: ");
+  if (sensors.readPowerSupply()) Serial.println("ON");  // no address means "scan all devices for parasite mode"
+  else Serial.println("OFF");
+
+  // Search for devices on the bus and assign based on an index.
+  if (!sensors.getAddress(insideThermometer, 0)) Serial.println("Unable to find address for Device 0");
+  if (!sensors.getAddress(outsideThermometer, 1)) Serial.println("Unable to find address for Device 1");
+
+  // show the addresses we found on the bus
+  Serial.print("Device 0 Address: ");
+  printAddress(insideThermometer);
+  Serial.println();
+  Serial.print("Power = parasite: ");
+  Serial.println(sensors.readPowerSupply(insideThermometer));
+  Serial.println();
+  Serial.println();
+
+  Serial.print("Device 1 Address: ");
+  printAddress(outsideThermometer);
+  Serial.println();
+  Serial.print("Power = parasite: ");
+  Serial.println(sensors.readPowerSupply(outsideThermometer));
+  Serial.println();
+  Serial.println();
+}
+
+// function to print a device address
+void printAddress(DeviceAddress deviceAddress)
+{
+  for (uint8_t i = 0; i < 8; i++)
+  {
+    // zero pad the address if necessary
+    if (deviceAddress[i] < 0x10) Serial.print("0");
+    Serial.print(deviceAddress[i], HEX);
+  }
+}
+
+// empty on purpose
+void loop(void)
+{
+}
+
+// END OF FILE

library.json

@@ -34,7 +34,7 @@
     "authors": "Paul Stoffregen",
     "frameworks": "arduino"
   },
-  "version": "3.8.0",
+  "version": "3.8.1",
   "frameworks": "arduino",
   "platforms": "*"
 }

library.properties

@@ -1,5 +1,5 @@
 name=DallasTemperature
-version=3.8.0
+version=3.8.1
 author=Miles Burton <[email protected]>, Tim Newsome <[email protected]>, Guil Barros <[email protected]>, Rob Tillaart <[email protected]>
 maintainer=Miles Burton <[email protected]>
 sentence=Arduino Library for Dallas Temperature ICs