Detecting Rotation Using a Gyroscope

Arduino-Detecting Rotation Using a Gyroscope:
         Most low-cost gyroscopes use an analog voltage proportional to rotation rate, although some also  output using I2C. This recipe works with a gyro with an analog output proportional to rotation rate. Figure 6-16 shows an LISY300AL breakout board from SparkFun. Many low-cost gyros, such as the one used here, are 3.3V devices and must not be plugged into the 5V power pin.The Gyro OUT connection is the analog output and is connected to Arduino analog input 0. The PD connection enables the gyro to be switched into low power mode and is connected to analog pin 1 (in this sketch, it is used as a digital output pin). You can connect PD to any digital pin; the pin used here was chosen to keep the wiring neater. If you don’t need to switch the gyro into low-power mode, you can connect the PD line to Gnd.

Reading RFID Tags using Arduino

RFID Connected with Arduino
A tag consists of a start character followed by a 10-digit tag and is terminated by an end character. The sketch waits for a complete tag message to be available and displays the tag if it is valid. The tag is received as ASCII digits (see Recipe 4.4 for more on receiving ASCII digits). You may want to convert this into a number if you want to store or compare the values received. To do this, change the last few lines as follows:
if( Serial.read() == endByte) // check for the correct end character
{
tag[bytesread] = 0; // terminate the string
long tagValue = atol(tag); // convert the ASCII tag to a long integer

Measuring Temperature LM35

Arduino-Measuring Temperature using LM35:
The LM35 temperature sensor produces an analog voltage directly proportional to temperature with an output of 1 millivolt per 0.1°C (10 mV per degree). The sketch converts the analogRead values into millivolts and divides this by 10 to get degrees. The sensor accuracy is around 0.5°C, and in many cases you can use integer math instead of floating point. The following sketch turns on pin 2 when the temperature is above a threshold:
       This recipe displays the temperature in Fahrenheit and Celsius (Centigrade) using the popular LM35

Detecting Vibration

Arduino-Detecting Vibration

           A Piezo sensor, also known as a knock sensor, produces a voltage in response to physical stress. The more it is stressed, the higher the voltage. The Piezo is polarized and the positive side (usually a red wire or a wire marked with a “+”) is connected to the analog input; the negative wire (usually black or marked with a “-”) is connected to ground. A high-value resistor (1 megohm) is connected across the sensor.
The voltage is detected by Arduino analogRead to turn on an LED. The THRESHOLD value determines the level from the sensor that will turn on the LED, and you can decrease or increase this value to
make the sketch more or less sensitive. Piezo sensors can be bought in plastic cases or as bare metal disks

Measuring Distance

Arduino-Measuring Distance using PING:
             Ultrasonic sensors provide a measurement of the time it takes for sound to bounce off an object and return to the sensor. The “ping” sound pulse is generated when the pingPin level goes HIGH for two microseconds. The sensor will then generate a pulse that terminates when the sound returns. The width of the pulse is proportional to the distance the sound traveled and the sketch then uses the pulseIn function to measure that duration. The speed of sound is 340 meters per second, which is 29 microseconds per centimeter. The formula for the distance of the round trip is: RoundTrip = microseconds / 29.So, the formula for the one-way distance in centimeters is: microseconds / 29 / 2.

Detecting Motion using Arduino

Detecting Motion-Integrating Passive Infrared Detectors
             This code is similar to the pushbutton. That’s because the sensor acts like a switch when motion is detected. Different kinds of PIR sensors are available, and you should check the information for the one you have connected. Some sensors, such as the Parallax, have a jumper that determines how the output behaves when motion is detected. In one mode, the output remains HIGH while motion is detected, or it can be set so that the output goes HIGH briefly and then LOW when triggered. The example sketch in this recipe’s Solution will work in either mode. Other sensors may go LOW on detecting motion. If your sensor’s output

Detecting Light using Arduino

AVR Arduino-Detecting Light:
       The circuit for this recipe is the standard way to use any sensor that changes its resistance based on some physical phenomenon. The circuit in will change the voltage on analog pin 0 when the resistance of the LDR changes with varying light levels. A circuit such as this will not give the full range of possible values from the analog input—0 to 1,023—as the voltage will not be swinging from 0 volts to 5 volts. This is because there will always be a voltage drop across each resistance, so the voltage where they meet will never reach the limits of the power supply. When using sensors such as these, it is important to check the actual values