Arduino Tutorial: Use a Piezo Element to Detect Vibration. This tutorial shows you how to use a Piezo element to detect vibration, in this case, a knock on a door, table, or other solid surface.

A piezo is an electronic device that generates a voltage when it’s physically deformed by a vibration, sound wave, or mechanical strain. Similarly, when you put a voltage across a piezo, it vibrates and creates a tone. Piezos can be used both to play tones and to detect tones.

The sketch reads the piezos output using the analogRead() command, encoding the voltage range from 0 to 5 volts to a numerical range from 0 to 1023 in a process referred to as analog-to-digital conversion, or ADC.

If the sensors output is stronger than a certain threshold, your Arduino will send the string “Knock!” to the computer over the serial port.

Open the serial monitor to see this text.

Hardware Required

• Arduino Board
• (1) Piezo electric disc
• (1) Megohm resistor
• solid surface

Piezos are polarized, meaning that voltage passes through them (or out of them) in a specific direction. Connect the black wire (the lower voltage) to ground and the red wire (the higher voltage) to analog pin 0. Additionally, connect a 1-megohm resistor in parallel to the Piezo element to limit the voltage and current produced by the piezo and to protect the analog input.

It is possible to acquire piezo elements without a plastic housing. These will look like a metallic disc, and are easier to use as input sensors. PIezo sensors work best when firmly pressed against, taped, or glued their sensing surface.

Schematic Diagram:

A Piezo to attached to analog pin 0 with a 1-Megohm resistor

Code

In the code below, the incoming piezo data is compared to a threshold value set by the user. Try raising or lowering this value to increase your sensor’s overall sensitivity.

/* Knock Sensor
This sketch reads a piezo element to detect a knocking sound.
It reads an analog pin and compares the result to a set threshold.
If the result is greater than the threshold, it writes
“knock” to the serial port, and toggles the LED on pin 13.
The circuit:
* + connection of the piezo attached to analog in 0
* – connection of the piezo attached to ground
* 1-megohm resistor attached from analog in 0 to ground

http://www.arduino.cc/en/Tutorial/Knock

created 25 Mar 2007
by David Cuartielles
modified 4 Sep 2010
by Tom Igoe
This example code is in the public domain.
*/
// these constants won’t change:
const int ledPin = 13; // led connected to digital pin 13
const int knockSensor = A0; // the piezo is connected to analog pin 0
const int threshold = 100; // threshold value to decide when the detected sound is a knock
or not
// these variables will change:
int sensorReading = 0; // variable to store the value read from the sensor pin
int ledState = LOW; // variable used to store the last LED status, to toggle the light
void setup() {
pinMode(ledPin, OUTPUT); // declare the ledPin as as OUTPUT
Serial.begin(9600); // use the serial port
}
void loop()
// read the sensor and store it in the variable sensorReading:
sensorReading = analogRead(knockSensor);
// if the sensor reading is greater than the threshold:
if (sensorReading >= threshold) {
// toggle the status of the ledPin:
ledState = !ledState;
// update the LED pin itself:
digitalWrite(ledPin, ledState);
// send the string “Knock!” back to the computer, followed by newline
Serial.println(“Knock!”);
}
delay(100); // delay to avoid overloading the serial port buffer
}

Download the Arduino Tutorial: Use a Piezo Element to Detect Vibration in PDF document:
» Download Link

On the Internet there are many examples of code for AVR-GCC , written using functions and macros that are no longer supported in newer versions of the compiler. To use these examples and understand them with the essence of the ports of the microcontroller, you need to rewrite code or use special macros.

For starters, learn programming AVR microcontrollers, this approach can be difficult. As a result, many go to other compilers and never use a cult which has become for many a development environment WinAVR. Although there is a simple way to solve all the problems and return again rejected by the developers of the functions in AVR-GCC. You can use a specially crafted AVR-GCC myROBOT PATCH for WinAVR .

Before we proceed to the description of the patch, let’s see what kind of function it returns. The latest versions of libraries avr-libc, which is part of the compiler AVR-GCC, uses a WinAVR, more functions are not supported inp , outp , sbi and CBI . Made it to the best interpretation of the source code when it is compiled and determine how to handle the port – how to register or to memory. Support for these functions is not starting from WinAVR-20050214 version. This includes no support for such a popular and convenient for many of the former bit_is_set and bit_is_clear .

Of course, nobody calls using only the “old” functions return the patch is backward-compatible programs on the AVR -GCC. Using the patch, you will not lose the ability to work with the new notation, and only return the use of excluded functions. For example, checking the work of any one found on the Internet example, you can practice by rewriting it with the new syntax.
In conclusion, let us consider some examples of possible replacements.

Please note that _BV () is preferable because in this case, the compiler performs a bitwise shift and inserts the result in the compiled code. This ensures that no time spent during direct execution of code in the microcontroller.
As you can see, the possibilities of syntax in the AVR-GCC wide enough to consider him one of the most convenient and flexible means of programming microcontrollers Atmel AVR.

NanoVM is a open-source implementation of the Java virtual machine. The NanoVM was initially developed to run on the Atmel AVR ATmega8 utilized in the Asuro Robot. It was ported to run on the C’t-Bot and the Nibo-robot and can easily be ported to other AVR-based systems.

The virtual machine uses almost 8 kilobytes of code memory (entire flash in case of ATmega8) and 256 bytes of RAM. Each and every user’s .class are processed by NanoVM’s Converter which transforms it into 1 bytecode file. Unique tools next send this file via serial line into device. For this operation is valuable NanoVM’s bootloader (alternatively you are able to use ISP programmer like: PonyProg) which store this content on-chip EEPROM.

NanoVM is not a full featured Java VM and it will never be.  It will constantly be limited to a tiny subset of the java language along with the regular java libraries plus a few application certain strategies. Furthermore, it really is not meant to replace C as the standard way of programming microcontrollers. It is much less flexible and has a lower performance than C or assembler programs.

The NanoVM is actually a method to present a limited but controllable programming interface to a microcontroller based device. With most of essentially the most hardware specific code being portion of the NanoVM itself, the user can focus on the application itself. If a user is given a device equipped using the NanoVM he is not needed to consider the hardware itself. Moreover, he does not need any target distinct compilers or the like. All he wants is a standard java compiler as well as the NanoVMTool which itself is written in java. Thus, the whole development chain works on any device that has a java compiler and can run java code. Using the hardware abstraction the NanoVM gives, the user doesn’t even have to care about the microcontroller type the target is based on. The very same java compiler as well as the identical NanoVMTool could be used with any NanoVM based program running on any sort of microontroller.

NanoWM documentation and download area: go to this page

Download the document of step by step Make a Robot tutorial:
Download Link

Go to online page of how to make a robot:
Visit the page

This tutorial explains all things related to the Atmel bootloader, including source code, how to install, programming, modification and uploading bootloader.

Tutorial document of Bootloader Tutorial for Atmel ATMega Microcontroller:
Download Link

Note: You must have the files required, go to this original page to download the files.

ROS is a robot operating system originally developed (2007) in the Stanford Artificial Intelligence Laboratory in support of the Stanford AI Robot (STAIR) project but now (as of 2008) developed primarily by Willow Garage, a robotics research institute/incubator. It is free for commercial and research use under a BSD license. The library runs primarily on Linux but is intended to be cross-platform for Mac OS X and Windows. ROS provides standard operating system services such as hardware abstraction, low-level device control, implementation of commonly-used functionality, message-passing between processes, and package management. It is a graph based architecture where processing takes place in nodes that may receive, post and multiplex sensor, control, state, planning, actuator and other messages.

ROS has two basic “sides”: The operating system side ros as described above and ros-pkg, a whole series of user contributed nodes that implement functionality such as Simultaneous localization and mapping, planning, perception, simulation etc.

ROS is released under the terms of the BSD license, and is open source software.

Applications

• ROS areas include
• A master coordination node
• Publishing or Subscribing to data streams (images, stereo, laser, control, actuator, contact …)
• Multiplexing information
• Node creation and destruction
• Nodes are seamlessly distributed, allowing distributed operation over multi-core, multi-processor, GPU and clusters.
• Logging
• Parameter server
• Test systems

ROS Package application areas will include

• Perception
• Object Identification
• Segmentation and Recognition
• Face Recognition
• Gesture Recognition
• Motion Tracking
• Ego-motion
• Motion Understanding
• Structure from motion (SFM)
• Stereopsis Stereo vision: depth perception from 2 cameras

Web site community for open source robot operating system is www.ros.org. If you wish to find out about Willow Garage’s role in developing ROS, please visit the Willow Garage Web site.

Ho it can be..?
There are many robot tutorial has been written and published through blog or web. I found interesting robot tutorial from this web. The author said that he build the robot just in 2 hours, you also can see the video there… just visit the web…

Plermjai Inchuay, plermjai@loxinfo.co.th

Award winner from VingPeaw Competition 2543, the robot built with 2051, L293D, and four IR sensors. Simple circuit and platform, quick tracking and easy-understand program using C language.

I designed my robot, which use two motors control rear wheels and the single front wheel is free. It has 4-infrared sensors on the bottom for detect black tracking tape, when the sensors detected black color, output of comparator, LM324 is low logic and the other the output is high. Microcontroller AT89C2051 and H-Bridge driver L293D were used to control direction and speed of motor.

Fig 1. Circuit diagram of my Robot.

Fig 2. Circuit diagram of Infrared sensors and comparators.

Fig 4. Position of sensors, left hand side is side view and right hand side is top view.

Software
Software for write to AT89C2051 is robot1.hex ,which was written by C-language ,the source code is robot1.c compiled by using MC51 in TINY model with my start up code robot.asm .MPEG files

Sample of competition between 2051 and 68HC11.

• movie1.mpg (1,303kB)
• movie2.mpg (373kB)

Source: www.kmitl.ac.th