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nanoFramework.Iot.Device.Ds18b20 1.0.903

Ds18b20 - Temperature Sensor

The DS18B20 digital thermometer provides 9-bit to 12-bit Celsius temperature measurements and has an alarm function with nonvolatile user-programmable upper and lower trigger points.

Documentation

Product datasheet can be found here

Sensor Image

Circuit

• DATA - RX2 + TX2 shorted
• VCC - 3.3V
• GND - GND

Important: make sure you've connected data pin of sensor to two pins on the board!

Usage

Important: make sure you properly setup the Rx/Tx pins especially for ESP32 before creating the OneWireHost, make sure you install the nanoFramework.Hardware.ESP32 nuget:

Configuration.SetPinFunction(16, DeviceFunction.COM3_RX);
Configuration.SetPinFunction(17, DeviceFunction.COM3_TX);

Library supports three approaches to read the data from Ds18b20 sensors:

1. Reading from first found sensor on OneWire bus or sensor with address passed as second parameter to the constructor:

 private static void ReadingFromOneSensor()
 {
 OneWireHost oneWire = new OneWireHost();


 Ds18b20 ds18b20 = new Ds18b20(oneWire, null, false, TemperatureResolution.VeryHigh);

 ds18b20.IsAlarmSearchCommandEnabled = false;
 if (ds18b20.Initialize())
 {
 Console.WriteLine($"Is sensor parasite powered?:{ds18b20.IsParasitePowered}");
 string devAddrStr = "";
 foreach (var addrByte in ds18b20.Address)
 {
 devAddrStr += addrByte.ToString("X2");
 }

 Console.WriteLine($"Sensor address:{devAddrStr}");

 while (true)
 {
 if (!ds18b20.TryReadTemperature(out var currentTemperature))
 {
 Console.WriteLine("Can't read!");
 }
 else
 {
 Console.WriteLine($"Temperature: {currentTemperature.DegreesCelsius.ToString("F")}\u00B0C");
 }

 Thread.Sleep(5000);
 }
 }


 oneWire.Dispose();
 }

2. Notification mode from first found sensor on OneWire bus or sensor with address passed as second parameter to the constructor:

private static void NotificationWhenValueHasChanged()
{
 OneWireHost oneWire = new OneWireHost();

 Ds18b20 ds18b20 = new Ds18b20(oneWire, null, false, TemperatureResolution.VeryHigh);

 if (ds18b20.Initialize())
 {
 ds18b20.SensorValueChanged += (currentTemperature) =>
 {
 Console.WriteLine($"Temperature: {currentTemperature.DegreesCelsius.ToString("F")}\u00B0C");
 };
 ds18b20.BeginTrackChanges(TimeSpan.FromMilliseconds(2000));
 // do whatever you want or sleep
 Thread.Sleep(60000);
 ds18b20.EndTrackChanges();
 }

 oneWire.Dispose();
}

3. Using alarms - alarm is a mode when sensor has value either higher or lower than defined tresholds.

private static void UsingAlarms()
{
 using OneWireHost oneWire = new OneWireHost();

 Ds18b20 ds18b20 = new Ds18b20(oneWire, null, false, TemperatureResolution.VeryHigh);

 if (ds18b20.Initialize())
 {
 for (int i = 0; i < ds18b20.AddressNet.Length; i++)
 {
 string devAddrStr = "";
 ds18b20.Address = ds18b20.AddressNet[i];

 foreach (var addrByte in ds18b20.AddressNet[i])
 {
 devAddrStr += addrByte.ToString("X2");
 }

 Console.WriteLine("18b20-" + i.ToString("X2") + " " + devAddrStr);

 ds18b20.ConfigurationRead(false);
 Console.WriteLine("Alarm set-points before changes:");
 Console.WriteLine("Hi alarm = " + ds18b20.TemperatureHighAlarm.DegreesCelsius + " C");
 Console.WriteLine("Lo alarm = " + ds18b20.TemperatureLowAlarm.DegreesCelsius + " C");
 SetAlarmSetting();
 }
 alarmSearch();
 }
 else
 {
 Console.WriteLine("No devices found.");
 }

 oneWire.Dispose();

 void alarmSearch()
 {
 int loopRead = 1000;
 ds18b20.IsAlarmSearchCommandEnabled = true;

 while (loopRead > 0)
 {
 Console.WriteLine("LoopRead " + loopRead);

 if (ds18b20.SearchForAlarmCondition())
 {
 for (int index = 0; index < ds18b20.AddressNet.Length; index++)
 {
 ds18b20.Address = ds18b20.AddressNet[index];
 if (ds18b20.TryReadTemperature(out var currentTemperature))
 {
 break;
 }

 string devAddrStr = "";
 foreach (var addrByte in ds18b20.AddressNet[index]) devAddrStr += addrByte.ToString("X2");
 Console.WriteLine("DS18B20[" + devAddrStr + "] Sensor reading in One-Shot-mode; T = " + currentTemperature.DegreesCelsius.ToString("f2") + " C");

 ds18b20.ConfigurationRead(false);
 Console.WriteLine("Alarm set-points:");
 Console.WriteLine("Hi alarm = " + ds18b20.TemperatureHighAlarm.DegreesCelsius + " C");
 Console.WriteLine("Lo alarm = " + ds18b20.TemperatureLowAlarm.DegreesCelsius + " C");
 }
 }
 else
 {
 Console.WriteLine("***** No devices in alarm ****");
 }

 loopRead--;
 }

 Console.WriteLine("");
 }

 void SetAlarmSetting()
 {
 ds18b20.TemperatureHighAlarm = Temperature.FromDegreesCelsius(30);
 ds18b20.TemperatureLowAlarm = Temperature.FromDegreesCelsius(25);
 // Write configuration on ScratchPad.
 ds18b20.ConfigurationWrite(false);
 // Write configuration on EEPROM too.
 ds18b20.ConfigurationWrite(true);
 // Read configuration to check if changes were applied
 ds18b20.ConfigurationRead(true);
 Console.WriteLine("Alarm set-points after changes:");
 Console.WriteLine("Hi alarm = " + ds18b20.TemperatureHighAlarm.DegreesCelsius.ToString("F") + " C");
 Console.WriteLine("Lo alarm = " + ds18b20.TemperatureLowAlarm.DegreesCelsius.ToString("F") + " C");
 }
}

Check samples project for more usage examples.