This is the application report from Texas Instruments about distance measurement using ultrasonic and MSP430 microcontroller. The report is provided in PDF file, you may download the application report at the end of this post.

This application report describes a distance-measuring system determined by ultrasonic sound using the MSP430F413 ultralow-power microcontroller. The system transmits a burst of ultrasonic sound waves towards the subject point and after that receives the corresponding echo.

This application is primarily based upon the reflection of sound waves. Sound waves are defined as longitudinal pressure waves in the medium in which they’re travelling. Subjects whose dimensions are greater than the wavelength of the impinging sound waves reflect them; the reflected waves are known as the echo. In the event the speed of sound in the medium is recognized and the time taken for the sound waves to travel the distance from the source towards the subject point and back to the source is measured, the distance from the source to the subject point will be computed accurately.

The devices applied to transmit and receive the ultrasonic sound waves within this application are 40-kHz ceramic ultrasonic transducers. The MSP430 drives the transmitter transducer using a 12-cycle burst of 40-kHz square-wave signal derived from the crystal oscillator, and therefore the receiver transducer receives the echo. The Timer_A in the MSP430 is configured to count the 40-kHz crystal frequency such that the time measurement resolution is 25 µs, that is more than enough for this application. The measurement time base is extremely stable because it is derived from a quartz-crystal oscillator. The echo received by the receiver transducer is boosted by an operational amplifier and the amplified output is fed towards the Comparator_A input. The Comparator_A senses the presence of the echo signal at its input and triggers a capture of Timer_A count value to capture compare register CCR1.

The capture is accomplished exactly at the immediate the echo arrives at the system. The captured count will be the measure of the time taken for the ultrasonic burst to travel the distance from the system to the subject point and back to the system. The distance in inches from the system towards the subject point is computed by the MSP430 implementing this measured time and displayed on a two-digit static LCD. Instantly right after updating the display screen, the MSP430 goes to LPM3 sleep mode to keep electrical power. The Basic Timer1 is programmed to interrupt the MSP430 every 205 milliseconds. The interrupt signal from the Basic Timer1 wakes up the MSP430 to repeat the measurement cycle and update the display screen.

Download the application report of distance measurement using ultrasonic and MSP430 microcontroller
» Download Link 1 (direct download from Texas Instruments)
» Download Link 1 (mirror download)

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

This is the tutorial of DC motor control system for robot application. The tutorial provided in powerpoint presentation sheet which is converted in PDF file. The tutorial contains information about motor control system especially for PID Closed loop control system: PID control system diagram, PID implementation, PID calculation, PID tuning and more.

You will also find the sample of simple PWM circuit, H-Bridge motor driver circuit and Optical encoder circuit in the document provided.

This Robot Tutorial of DC Motor Control System can be accessed at dprg.org or you can download the presentation file here

Robotic voice generator does not need the variety of complex chips. You can assemble using only ISD2500 ChipCorder® family and few components.The family of chip-coders ISD2500 firm Winbond contains almost everything you need to record and play back voice messages. As chips have mic preamps with AGC, working with the cheapest electret microphones, the output amplifier that runs on the speaker, memory, oscillator, ADC and DAC.

In a family of four basic models: 2560, 2575, 2590 and 25 120. The number following the numerals 25 denotes a maximum recording time in seconds. The amount of memory chips all the same, and long duration recording is achieved by a lower sampling rate. Ie, the chip with the lowest recording time provides the best sound quality.

Steps to follow when writing

First of all, set switch S3 to the recording mode (low level at pin 27). When you press S2 recording mode, which will end after pressing S2. With the third click again to start recording, etc. So you can continue for as long as the record will be nothing, or until the LED D2, indicating that the memory is full.

Steps to follow when playing

Playback can be started immediately, including the S1 and S3 in the switching mode “play”. Now, with every touch of S2, will consistently play the recorded messages. To record a new message over the old, turn S1, S3 switched to “record”, and pressing the S2, start recording again.

Some flexibility in the organization of the play mode allows you to connect together fragments of messages. Each piece ends with the flag of EOM (End Of Message – End of Posts), which is stored in the memory chip. So, instead of storing entire phrases, such as the “obstacle in front,” is much more efficient to keep an “obstacle”, “front”, “right”, “left”, “rear”. Similarly, for the numbers: from individual elements of the “one” “two”, “hundred”, “point”, etc. You can collect any number.

The Robotic voice generator scheme, managed by a microcontroller, is shown in the figure. Signals A0, PD, / CE and / EOM connected to a microcontroller that controls the robot.

To play you must first set to “0″ signal PD. To play the first message, the input / CE must submit a negative pulse. If this level of input A0 “0″, the playback will occur at normal speed, and if “1″ – a rate 800 times greater – a sort of “fast forward”. If you want after the first report was made, for example, the third, the microcontroller must set the “1″ to A0 and submit a negative pulse / CE, to “squander” the second message with great speed. Then, after waiting for the installation of the flag / EOM at a low level, A0 must be reset to “0″ and pulse / CE start playing the third message.

Due to the fact that the pulse duration / EOM may be less than 10 ms, it is better to use it to interrupt the processor, but do not check status / EOM interviews.

Here is the pcb layout :

Details :

L293D chip 
socket for the chip to 16 feet 
capacitor C6 to 1000 uF 25 volt 
capacitors C1-C5 0.1 uF 
Resistors R1-R6 100 ohm 
resistors R7-R12 at 220 ohms

There are many various schemes for motor control. They differ in how capacity and element basis on which they are made. We will focus on the simplest driver motor control, performed in a completely ready for operation in the chip. This chip is called the L293D is one of the most popular chips intended for this purpose.

L293D contains just two drivers to control the motors of low power (four independent channels, combined in two pairs). It has two sets of inputs for control signals and two pairs of outputs for connecting electric motors. In addition, the L293D has two entrances to the inclusion of each of the drivers. These inputs are used to control the speed of electric motors using pulse width modulated signal (PWM).

L293D division provides power for the chip and its controlled motors, allowing you to connect motors with high-voltage power supply than the chip. The separation of power circuits and electric motors may also be necessary to reduce interference caused by the Surge, work-related motors.

The principle of operation of each of the drivers included in the circuit is identical, so we consider the principle of one of them.

OUTPUT1 and OUTPUT2 connected to MOTOR1. The input ENABLE1, including the driver, will submit a signal (connected to the positive pole of power supply +5 V). If, in the inputs and INPUT1 INPUT2 does not beep, then the motor will not rotate. If the input INPUT1 connect the positive terminal of power supply and input INPUT2 – with the negative, the motor starts to rotate. Now let’s connect the input to the negative pole INPUT1 supply and input INPUT2 – positive. Motor starts to rotate in the opposite direction. Let us apply the same level of signals at once on both control inputs and INPUT1 INPUT2 (both inputs to connect the positive terminal of the power supply or a negative) – the motor will not rotate. If we remove the signal from the input ENABLE1, then for any variants having the input signals and INPUT1 INPUT2 motor will not rotate. Provide better principle of the driver motor can be, consider the following table:

ENABLE1	INPUT1	INPUT2	OUTPUT1	OUTPUT2
1	0	0	0	0
1	1	0	1	0
1	0	1	0	1
1	1	1	1	1

Now consider the appointment of pins L293D.

• Inputs and ENABLE1 ENABLE2 responsible for the inclusion of each of the drivers that are part of the chip.
• Inputs and INPUT1 INPUT2 run the engine, connected to the outputs and OUTPUT1 OUTPUT2.
• Inputs and INPUT3 INPUT4 run the engine, connected to the outputs and OUTPUT3 OUTPUT4.
• Contact Vs is connected to the positive pole of a power supply of engines or just the positive terminal of power supply when the power supply circuit and a single engine. Simply put, this contact is responsible for the supply of electric motors.
• Contact Vss is connected to the positive pole of power supply. This pin provides power to the chip itself.
• Four pins GND is connected to “ground” (the common wire or the negative pole of power supply). In addition, through these contacts typically provide heat from the chip, so it is best to unsolder a sufficiently wide contact area.

Characteristics of IC L293D

• voltage motors (Vs) – 4,5 … 36V
•  voltage integrated circuits (Vss) – 5V
• allowable load current – 600mA (per channel
• peak (maximum) output current – 1,2 A (per channel)
• logical “0″ input voltage – up to 1,5 V
• logical “1″ input voltage – 2,3 … 7V
• Switching speed of up to 5 kHz.
• Protection against overheating

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

Arduino UNO Board:

Arduino UNO Schematic:

Adruino UNO Schematic and PCB Design Download:
EAGLE files (rev2): arduino-uno-rev2-reference-design.zip
Schematic (rev2): arduino-uno-rev2-schematic.pdf
EAGLE files (original): arduino-uno-reference-design.zip
Schematic (original): arduino-uno-schematic.pdf

Arduino Tutorial:
» Go to this page

Ardunio Software Download:
» Go to this page

About Arduino UNO:
The Arduino UNO is really a microcontroller board based on the ATmega328. It has 14 digital input/output pins (of which 6 can be utilised as PWM outputs), 6 analog inputs, a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, along with a reset button. It contains every thing necessary to support the microcontroller; merely connect it to a computer having a USB cable or power it having a AC-to-DC adapter or battery to get began.

The UNO differs from all preceding boards in that it doesn’t use the FTDI USB-to-serial driver chip. Instead, it characteristics the Atmega8U2 programmed as a USB-to-serial converter.

“UNO” means one in Italian and is named to mark the upcoming release of Arduino 1.0. The Uno and version 1.0 is going to be the reference versions of Arduno, moving forward. The Uno is the latest in a series of USB Arduino boards, along with the reference model for the Arduino platform; for a comparison with previous versions, see the index of Arduino boards.

This is the project report for cellphone controlled mobile robot by Gaurav A.Khadasane, Tejas  Jethwa, Suraj,  Akshay Sonawale. You may use this document for your robot building project reference.

Detail module used for cellphone controlled mobile robot:

• DTMF Decoder: MT8870/CM8870
• Microcontroller: ATMEGA16
• Motor Driver: L293D
• Actuator: DC Motor 5-6V

Download Cellphone Controlled Mobile Robot Tutorial:
Download Link
Learn how to make mobile robot controlled
by a cellphone

• Simple 87LPC76x Microcontroller Tutorial
• Using the 87LPC76X microcontroller as an I²C bus master
• Using the 87LPC76X in multi-master I²2C applications
• Using the Philips 87LPC76x microcontroller as a remote control transmitter

About P87LPC760 Microcontroller:
The P87LPC760 is known as a 14-pin single chip microcontroller developed for applications demanding highintegration, minimal price solutions over a wide range of performance requirements. It’s based on an 80C51 processor architecture that executes instructions at twice the rate of standard 80C51 devices.

Download Philips 87LPC76x Microcontroller Tutorial and Application:
» Download Link