Category:

Arduino Sensors

Arduino MCP9808 digital temperature sensor

by shedboy71 8th July 2016

written by shedboy71

The MCP9808 digital temperature sensor converts temperatures between -20°C and +100°C to a digital word with ±0.5°C (max.) accuracy. The MCP9808 comes with user-programmable registers that provide flexibility for temperature sensing applications. The registers allow user-selectable settings such as Shutdown or low-power modes and the specification of temperature Event and Critical output boundaries.

When the temperature changes beyond the specified boundary limits, the MCP9808 outputs an Event signal. The user has the option of setting the event output signal polarity as an active-low or active-high comparator output for thermostat operation, or as temperature event interrupt output for microprocessor-based systems. The event output can also be configured as a Critical temperature output. This sensor has an industry standard 2-wire, SMBus and Standard I2C™Compatible compatible (100kHz/400kHz bus clock) serial interface, allowing up to eight sensors to be controlled in a single serial bus.
Features

Accuracy:
±0.25°C (typical) from -40°C to +125°C
±0.5°C (maximum) from -20°C to +100°C

User Selectable Measurement Resolution:
0.5°C, 0.25°C, 0.125°C, 0.0625°C

User Programmable Temperature Limits:
Temperature Window Limit
Critical Temperature Limit

User Programmable Temperature Alert Output
Operating Voltage Range: 2.7V to 5.5V

More details about the sensor at http://www.microchip.com/wwwproducts/en/MCP9808

This typically comes in a breakout such as the one in the breakout below

MCP9808 digital temperature sensor

Code

You will need the adafruit MCP9808 library which is available at https://github.com/adafruit/Adafruit_MCP9808_Library/archive/master.zip

[codesyntax lang=”cpp”]

#include <Wire.h>
#include "Adafruit_MCP9808.h"

// Create the MCP9808 temperature sensor object
Adafruit_MCP9808 tempsensor = Adafruit_MCP9808();

void setup() {
  Serial.begin(9600);
  
  if (!tempsensor.begin()) 
  {
    Serial.println("Couldn't find MCP9808!");
    while (1);
  }
}

void loop() {
  // Read and print out the temperature, then convert to *F
  float c = tempsensor.readTempC();
  float f = c * 9.0 / 5.0 + 32;
  Serial.print("Temp: "); 
  Serial.print(c); 
  Serial.print(" C\t"); 
  Serial.print(f); 
  Serial.println(" F");
  delay(250);
  
  tempsensor.shutdown_wake(1);
  delay(2000);
  tempsensor.shutdown_wake(0);
  
   
}

[/codesyntax]

Results

Open the serial monitor and you should see something like this

Temp: 21.69 C 71.04 F
Temp: 21.62 C 70.93 F
Temp: 24.50 C 76.10 F
Temp: 25.06 C 77.11 F
Temp: 25.37 C 77.68 F
Temp: 25.56 C 78.01 F
Temp: 24.25 C 75.65 F
Temp: 23.87 C 74.97 F

Links

Adafruit MCP9808 High Accuracy I2C Temperature Sensor Breakout Board [ADA1782]

8th July 2016 0 comment

Arduino Sensors

Arduino HDC1008 sensor example

by shedboy71 8th July 2016

written by shedboy71

The HDC1000 is a digital humidity sensor with integrated temperature sensor that provides excellent measurement accuracy at very low power. The device measures humidity based on a novel capacitive sensor. The humidity and temperature sensors are factory calibrated.

The sensing element of the HDC1000 is placed on the bottom part of the device, which makes the HDC1000 more robust against dirt, dust, and other environmental contaminants. The HDC1000 is functional within the full –40°C to +125°C temperature range.

Key Features

Relative Humidity (RH) Operating Range 0% to 100%
14 Bit Measurement Resolution
Relative Humidity Accuracy ±3%
Temperature Accuracy ±0.2°C
Supply Voltage 3 V to 5 V
I2C Interface

Connection information

The easiest way is to purchase some sort of breakout

Connect Vin to 5VDC
Connect GND to ground
Connect SCL to A5 on UNO
Connect SDA to A4 on UNO

Code

The good folks at Adafruit have done the hard work and produced a library for this device – https://github.com/adafruit/Adafruit_HDC1000_Library . If you are using Arduino IDE 1.6.5 or later you can easily import this library by going to Sketch -> Include Library -> Manage Libraries

[codesyntax lang=”cpp”]

#include <Wire.h>
#include "Adafruit_HDC1000.h"


Adafruit_HDC1000 hdc = Adafruit_HDC1000();

void setup() 
{
  Serial.begin(9600);
  Serial.println("HDC100x test");

  if (!hdc.begin()) 
  {
    Serial.println("Couldn't find sensor!");
    while (1);
  }
}


void loop() 
{
  Serial.print("Temp: "); Serial.print(hdc.readTemperature());
  Serial.print("\t\tHum: "); Serial.println(hdc.readHumidity());
  delay(500);
}

[/codesyntax]

Links

Adafruit HDC1008 Temperature & Humidity Sensor Breakout Board

8th July 2016 0 comment

Arduino Sensors

Arduino BME280 sensor example

by shedboy71 8th July 2016

written by shedboy71

The BME280 is a humidity sensor features an extremely fast response time which supports performance requirements for emerging applications such as context awareness, and high accuracy over a wide temperature range. The pressure sensor is an absolute barometric pressure sensor with features exceptionally high accuracy and resolution at very low noise. The integrated temperature sensor has been optimized for very low noise and high resolution. It is primarily used for temperature compensation of the pressure and humidity sensors, and can also be used for estimating ambient temperature.

The best way to use the device is a module like the one pictured below

I found this schematic for a breakout online for the bme280, you’ll see in the sparkun image above they are using 4k7’s rather than 10K

Sparkfun has all of the design files for their module available from https://github.com/sparkfun/SparkFun_BME280_Breakout_Board ,

You can use this module in either SPI or I2C modes, in this case we went for SPI mode, here is the wiring for our module to our arduino Uno

Connect Vin to 5V.
Connect GND to ground
Connect the SCK pin to Digital #13
Connect the SDO pin to Digital #12
Connect the SDI pin to Digital #11
Connect the CS pin Digital #10

Code

The code uses the sparkfun library, I tried 2 others and couldn’t get them to compile. There are several examples available. I removed some code from a basic example

Library – https://github.com/sparkfun/SparkFun_BME280_Arduino_Library

[codesyntax lang=”cpp”]

#include <stdint.h>
#include "SparkFunBME280.h"
#include "Wire.h"
#include "SPI.h"

//Global sensor object
BME280 mySensor;

void setup()
{
  Serial.begin(57600);
  //SPI
  mySensor.settings.commInterface = SPI_MODE;
  mySensor.settings.chipSelectPin = 10;

  //Operation settings
  mySensor.settings.runMode = 3; //Normal mode
  mySensor.settings.tStandby = 0;
  mySensor.settings.filter = 0;
  mySensor.settings.tempOverSample = 1;
  mySensor.settings.pressOverSample = 1;
  mySensor.settings.humidOverSample = 1;
  
  Serial.print("Starting BME280... result of .begin(): 0x");
  delay(10);  //BME280 requires 2ms to start up.
  Serial.println(mySensor.begin(), HEX);
  
}

void loop()
{
  //Each loop, take a reading.

  Serial.print("Temperature: ");
  Serial.print(mySensor.readTempC(), 2);
  Serial.println(" degrees C");

  Serial.print("Temperature: ");
  Serial.print(mySensor.readTempF(), 2);
  Serial.println(" degrees F");

  Serial.print("Pressure: ");
  Serial.print(mySensor.readFloatPressure(), 2);
  Serial.println(" Pa");

  Serial.print("Altitude: ");
  Serial.print(mySensor.readFloatAltitudeMeters(), 2);
  Serial.println("m");

  Serial.print("Altitude: ");
  Serial.print(mySensor.readFloatAltitudeFeet(), 2);
  Serial.println("ft"); 

  Serial.print("%RH: ");
  Serial.print(mySensor.readFloatHumidity(), 2);
  Serial.println(" %");
  
  Serial.println();
  
  delay(1000);

}

[/codesyntax]

Output

All going well if you open your serial monitor window you should see something like this

Temperature: 22.55 degrees C
Temperature: 72.61 degrees F
Pressure: 100637.00 Pa
Altitude: 59.39m
Altitude: 194.01ft
%RH: 0.00 %

Temperature: 22.54 degrees C
Temperature: 72.57 degrees F
Pressure: 100640.00 Pa
Altitude: 59.13m
Altitude: 194.58ft
%RH: 0.00 %

Temperature: 22.53 degrees C
Temperature: 72.59 degrees F
Pressure: 100638.00 Pa
Altitude: 59.31m
Altitude: 195.99ft
%RH: 0.00 %

The temperature looked accurate, I looked up the air pressure and altitude of my location on the internet. Not bad on air pressure as I looked it up a bit later than when I gathered the readings

Pressure	1011.2 mb, Steady [Min 1010.5 Max 1012.5]

Altitude was about 40m out, according to http://elevationmap.net. I’ll need to investigate this as that’s not that good

Links

You can pick up one of these breakout/modules for under $8
BME280 Embedded high-precision barometric pressure sensor module

8th July 2016 0 comment

Arduino Sensors

Arduino and AM2302 humidity and temperature sensor

by shedboy71 5th July 2016

written by shedboy71

In this example we use the DHT22 (or AM2302) humidity/temperature sensor and the Arduino UNO board to read data and print it out to the serial monitor.

The DHT22 is better than the DHT11 because it has a wider range of measurement, 0 to 100% for humidity and -40°C to +125°C for temperature. Also it has a digital output that provides greater data accuracy.

I used a breakout , again it makes the job easier and doesn’t really add to the cost of a project

DHT22 Digital Humidity AM2302 and Temperature Sensor Module For Arduino

Breadboard layout

The resistor should be 4.7k in the layout below

dht22 breadboard layout

Code

Import the DHT11 library from Adafruit, in later versions of the Arduino IDE you can do this in the library manager. You can see this in the screenshot below

[codesyntax lang=”cpp”]

#include "DHT.h"
 
#define DHTPIN 6     // what pin we're connected to
#define DHTTYPE DHT22   // DHT 22  (AM2302)

 
DHT dht(DHTPIN, DHTTYPE);
 
void setup() 
{
  Serial.begin(9600); 
  dht.begin();
}
 
void loop() 
{
  // Wait a few seconds between measurements.
  delay(2000);
 
  float hum = dht.readHumidity();
  // Read temperature as Celsius
  float tempC = dht.readTemperature();
  
  // Check if readings have failed
  if (isnan(hum) || isnan(tempC)) 
  {
    Serial.println("Failed to read from DHT sensor!");
    return;
  }     
  
  Serial.print("Humidity: "); 
  Serial.print(hum);
  Serial.print(" %\t");
  Serial.print("Temperature: "); 
  Serial.print(tempC);
  Serial.println(" *C ");
 
}

[/codesyntax]

Links

DHT22 Digital Humidity AM2302 and Temperature Sensor Module

http://akizukidenshi.com/download/ds/aosong/AM2302.pdf

5th July 2016 0 comment

Arduino Sensors

Arduino and SHT21 humidity and temperature sensor

by shedboy71 5th July 2016

written by shedboy71

Description

The digital SHT2x humidity sensor series is used in high volumes in a wide variety of applications and has today become the de facto industry standard. The SHT2x series consists of a low-cost version with the SHT20 humidity sensor, a standard version with the SHT21 humidity sensor, and a high-end version with the SHT25 humidity sensor. The open cavity mold package – which encapsulates the complete chip except for the humidity sensor area – protects the capacitive humidity sensor against external impact and facilitates excellent long-term stability.

Features

Size : 3 x 3 x 1.1 mm
Output : I²C digital, PWM, SDM
Supply voltage range : 2.1 to 3.6 V
Energy consumption : 3.2µW (at 8 bit, 1 measurement / s)
RH operating range : 0 – 100% RH
T operating range : -40 to +125°C (-40 to +257°F)

Its an I2C device so again is very simple to connect to any arduino

This is the breakout for the sensor that I bought, as you can see its a tricky part to use for the hobbyist, so a breakout makes like easier

Here is a simple schematic, again be careful as Vcc is 3.3v with this device

Schematic

SHT21 schematic

Lets look at the required libraries and a basic code example, there is not much to this to be honest most of the work is done in the library

Code

There are a couple of libraries to help you out

https://github.com/misenso/SHT2x-Arduino-Library
https://github.com/elechouse/SHT21_Arduino

I used the latter one

[codesyntax lang=”cpp”]

#include <Wire.h>
#include <SHT2x.h>


void setup()
{
  Wire.begin();
  Serial.begin(9600);
}

void loop()
{
  Serial.print("Humidity: ");
  Serial.println(SHT2x.GetHumidity());
  Serial.print("Temperature(C): ");
  Serial.println(SHT2x.GetTemperature());
  Serial.println();
  delay(1000);
}

[/codesyntax]

Links

these come in at about $7 for a useful breakout board with this sensor

SHT21 Digital Humidity And Temperature Sensor Module

5th July 2016 0 comment

Arduino Sensors

Arduino and ML8511 UV light sensor

by shedboy71 5th July 2016

written by shedboy71

Description

The ML8511 measures the amount of ultra violet rayses contained in sunlight, and it is used for the equipment which displays the suntan by a ultra violet rays, the guidance for UV care of skin, etc

The sensor detects 280-390nm light most effectively. This is categorized as part of the UVB (burning rays) spectrum and most of the UVA (tanning rays) spectrum. It outputs a analog voltage that is linearly related to the measured UV intensity (mW/cm2). If your microcontroller can do an analog to digital signal conversion then you can detect the level of UV!

Its breakout time again as this sensor is difficult to use otherwise for the normal hobbyist as it would require very good soldering skills due to the type of package

ML8511 module

For those at are interested here is a schematic of this module

Connections

3.3V = 3.3V source
OUT = A0
GND = GND
EN = 3.3V

Code

[codesyntax lang=”cpp”]

int UVsensorIn = A0; //Output from the sensor

void setup()
{
pinMode(UVsensorIn, INPUT);
Serial.begin(9600); //open serial port, set the baud rate to 9600 bps
}

void loop()
{
int uvLevel = averageAnalogRead(UVsensorIn);

float outputVoltage = 3.3 * uvLevel/1024;
float uvIntensity = mapfloat(outputVoltage, 0.99, 2.9, 0.0, 15.0);

Serial.print(” UV Intensity: “);
Serial.print(uvIntensity);
Serial.print(” mW/cm^2″);
Serial.println();
delay(200);
}

//Takes an average of readings on a given pin
//Returns the average
int averageAnalogRead(int pinToRead)
{
byte numberOfReadings = 8;
unsigned int runningValue = 0;

for(int x = 0 ; x < numberOfReadings ; x++)
runningValue += analogRead(pinToRead);
runningValue /= numberOfReadings;

return(runningValue);

}

float mapfloat(float x, float in_min, float in_max, float out_min, float out_max)
{
return (x – in_min) * (out_max – out_min) / (in_max – in_min) + out_min;
}
[/codesyntax]

Links

ML8511 UVB Ray Detection Module

5th July 2016 0 comment

Arduino Sensors

Arduino and DHT11 Temperature and Humidity Sensor example

by shedboy71 5th July 2016

written by shedboy71

Description

In this example we will show a basic example of connecting a DHT11 Temperature and Humidity Sensor to your Arduino. This is a very nice little, low cost sensor which requires only a pull up resistor to VDD. This can easily be constructed on a mini bread board and then joined up to your Arduino. using some connecting cables

The DHT sensors are made of two parts, a capacitive humidity sensor and a thermistor. There is a chip inside that does some a/d conversion and outputs a digital signal with the temperature and humidity. Again you can purchase the sensor and resistor seperately but I prefer to use a little module/breakout, there are many options available such as the one below

DHT11 temperature and humidity sensor module

I wont go into the technical details of the DHT11, there is a link at the bottom to a PDF datasheet which explains all you need to know.

Parts List

Label	Part Type
DHT1	DHT11 Humitidy and Temperature Sensor	
Part1	Arduino Uno (Rev3)
R1	4.7k Ω

Schematic

Arduino and DHT11 schematic

Breadboard layout

Arduino and DHT11 breadboard layout

Code

You will need either the DHT11 library from the DHT library. Download, extract and copy this to your Arduino libraries folder location.

In later versions of the Arduino IDE you can use the library manager and search for the DHT11 library from Adafruit and add it, you can see this in the screenshot below

dht11 library manager

This is a simple example which outputs the humidity and temperature, place a heat source such as your hand on the DHT11 and you will see the readings fluctuate

[codesyntax lang=”cpp”]

#include <dht11.h>

dht11 DHT;
//Pin 4 of Arduino to Data of DHT11
#define DHT11_PIN 4

void setup()
{
Serial.begin(9600);
int check;
Serial.print(“DHT11 STATUS – \t”);
check = DHT.read(DHT11_PIN);
//check status
switch (check)
{
case DHTLIB_OK:
Serial.print(“OK\n”);
break;
case DHTLIB_ERROR_CHECKSUM:
Serial.print("Checksum error\n");
break;
case DHTLIB_ERROR_TIMEOUT:
Serial.print("Timeout error\n");
break;
default:
Serial.print("Unknown error\n");
break;
}
}

void loop()
{

//humidity and temperature output
Serial.print(“Humidity is “);
Serial.print(DHT.humidity,1);
Serial.print(“\n”);
Serial.println(“Temperature is “);
Serial.println(DHT.temperature,1);

delay(1000);
}

[/codesyntax]
Output

Upload the sketch above and open the Serial Monitor window and you should see something like the following

Links
DHT11 Temperature And Relative Humidity Sensor Module
DHT11 Datasheet in PDF format

5th July 2016 0 comment

Arduino Sensors

Arduino and DS18B20 temperature sensor example

by shedboy71 5th July 2016

written by shedboy71

Description

The DS18B20 is a temperature sensor that can be used in various simple projects. This part uses the 1 wire (I2C) bus and you can connect multiple sensors up to your Arduino.

The part is also relatively low cost and only requires an additional 4k7 pull up resistor. In the example below we shall make a basic example that reads the temperature and outputs via serial and can be verified using the serial monitor in the Arduino IDE.

Parts List

Label	Part Type
DS1	DS18B20 1-Wire Temperature Sensor
Part1	Arduino Uno (Rev3)
R1	4.7k Ω Resistor

As always be careful not to get the connections incorrect, you can refer to the pinout for the device below to help . The DS18B20 can be powered by between 3.0V and 5.5V so you can simply connect its GND pin to 0V and the VDD pin to +5V from the Arduino.

ds18b20 pinout

I personally find that using a module is the easiest way, the components are soldered for you and the connections come out to a header, here is a module that I have used

AliExpress.com Product – DS18B20 temperature module temperature sensor module

Breadboard layout

Here is the connection diagram showing how to connect your arduino to the resistor and sensor.

ds1820 breadboard layout

Code

There are a couple of libraries and copy them into your Arduino libraries folder.

Dallas 18b20 Temperature Library
“1-Wire” Library

Now copy and paste the following code into a new sketch

[codesyntax lang=”cpp”]

#include <OneWire.h>
#include <DallasTemperature.h>

//the pin you connect the ds18b20 to
#define DS18B20 2

OneWire ourWire(DS18B20);
DallasTemperature sensors(&ourWire);

void setup()
{
Serial.begin(9600);
delay(1000);
//start reading
sensors.begin();
}

void loop()
{
//read temperature and output via serial
sensors.requestTemperatures();
Serial.print(sensors.getTempCByIndex(0));
Serial.println(" degrees C");
}

[/codesyntax]

Output

When you upload the sketch, go to Tools -> Serial Monitor and you should see something like the following.

ds18b20 serial output

Links
DS18B20 Stainless Steel Waterproof Temperature Probe Sensor For Arduino

DS18B20 temperature module temperature sensor module

5th July 2016 0 comment