VR Stamp development kit by mikroElektronika

For those who dream about embedding speech, music & voice recognition in their systems, Sensory Inc. has built a powerful RSC-4128 based stamp.
MikroElektronika released in March 2006 a complete development kit system for this stamp, with a board named Easy-VR Stamp, and a C compiler named RSC-4x mikroC compiler.
As a user of this tools, here is a little review of what you have to know about it.
Later, I will add some VR Stamp C source code examples, just like I do for PICs.

1/ What comes with the MikroElektronika Easy VR-Stamp development system
Unpacking the box, here is what I found :
From top to bottom, and from left to right :

• the CD with software. I did not use it, I explain why below
• the most important : the board, with a VR Stamp plugged into its socket
• a 2 lines x 16 characters LCD display (not included in the base package, sold separately)
• the USB cable to connect the on-board programmer to the host computer
• a serial cable to connect the VR Stamp to a host computer (RS232 level adapter is on the board)
• the board manual with schematic.

Automatic LED display dimmer | microcontroller Project

This example shows how to use a simple LED as light sensor, and to dim a 7-segments LED display with PWM automatically in the dark.
You will use :

• the PIC analog input and its ADC
• the PIC timer 0
• a 4 digits 7 segments LED display
• 2 buttons
• a simple LED diode

Did you ever use 7 segments LED display ? Of course yes.
Then you surely adjusted the brightness of the LED, so that it is clearly readable in the day light.
But what happens in the dark ? Your display is simply too much bright !
How to know if it is bright or dark, without adding an analog extra-circuit ?
How to control the brightness of the display, without adding an analog extra-circuit ?

1. A LED as light sensor ?

Simple & Cheap Thermometer

This example shows how to rapidly build a simple and cheap thermometer with a PIC, and to experiment in on an EasyPic2 or EasyPic3 board.
You will use :

• the PIC analog input and its ADC
• the PIC timer 0
• a 4 digits 7 segments LED display
• 3 buttons
• a simple silicon diode

Did you ever have to control a fan speed rotation ?
Did you ever need to have an idea about the air temperature in your fridge ? in your PC case ?  in your basement ? in your attic ?
Did you ever need to automatically shut down a device, to prevent it from overheating ? or to power it up, in order to pre-heat it ?
Is a 2°C accuracy good enough for your project ?
You don't mind to calibrate it once ?
You don't want to spend too much for it ?
You want to build it right now ?
GOOD ! if you have a PIC with an internal ADC, and a diode in your drawers, you are ready !

 1. Select a temperature sensor

Temperature sensors are widely used, here are most common families :

Family	Output	Accuracy	Integration	Cost
NTC & PTC Resistors (Thermistors)	ANALOG	GOOD	Easy	Low
Thermocouples	ANALOG	HIGH	Hard	High
Resistance temperature detectors (RTDs)	ANALOG	HIGH	Hard	High
IR Thermometers	ANALOG	HIGH	Hard	High
ICs	DIGITAL	HIGH	Easy	Medium
Bimetal	BINARY	LOW	Very Easy	Low
Diodes	ANALOG	GOOD	Easy	Very Low

Creat easily Multiple non-blocking delays with 1 timer

This example shows you how to create multiple non-blocking delays with only one timer, using :

• timer 1
• interrupts
• arrays of pointers to functions
• structures

It is made for a P18F452 but it could be used with others pics with just minor adjustments.

/*
 * this source code shows how to use pic timers, interrupts, 

and arrays of pointers to functions
 * and how to make non-blocking multiples delays, using a single timer
 *
 * Bruno Gavand, march 2006
 * www.micro-examples.com
 *
 * P18F452 @8Mhz, HS clock, EASYPIC2 / EASYPIC3
 * pull-down on PORTB
 * pull-up on keyboard
 * enable PORTB, PORTC and PORTD LEDs
 *
 * pressing RB0 key will toggle PORTC after a 2s non-blocking delay
 * pressing RB1 key will toggle PORTD after a 3s non-blocking delay
 *
 * used ROM : 1676 bytes
 */

More click on title..

Single-Tube nixie clock | Microcontroller Project

Here is the nixie clock !

• PIC16F84A microcontroller
• Single-digit Nixie, sequential hours, minutes and seconds display 
• DCF-77 atomic clock, with automatic or manual time set-up
• high voltage power supply for Nixie with only 4 components
• 24 hours cycle programmable extinction time
• no MikroC compiler licence needed !

 This project will show you how to drive a nixie tube display with a PIC16F84A simple microcontroller.
The nixie is a vertical-mount, front-reading IN-14 russian tube (thanks Alex !), very convenient for prototyping because of its long solderable pins.
  How to power the nixie ?
A 170 volt power supply must be applied between the anode of the tube and one of its cathod, to light the corresponding number from 0 to 9. The lightened number needs around 1.5 mA to glow.
If the voltage is lower, the number is not completely lightened and may even extinguish (under 140 V).
If the voltage is higher, digits will randomly light at the same time, and no digit will be clearly readable.
It is possible to get the high voltage from the main power supply, but it is highly dangerous because live parts may be exposed to dangerous voltage.
That's why is use a DC/DC converter, which gives the +170V needed by the nixie from the +5V power supply of the circuit.
The PIC16F84A generates a software PWM, and drives the MOSFET's gate. The MOSFET switches on an off the current into a 300 µH coil. The inducted high voltage is collected by a fast recovery diode and then fed into a capacitor.

Simple Frequency Meter | Microcontroller Project

This section will show you how to build this f-meter :

• PIC16F84 microcontroller
• RS232 text output
• one output per second
• basic frequency range from 0 to 83 KHz with 20 Mhz crystal
• 1 Hz accuracy
• no extra component !
• can be build without MikroC compiler licence !

and make it run on a EasyPic development circuit board.
The C language source code is freely provided !

This is the source code for building a very simple, but efficient frequency-meter, you can test it directly with an EasyPic board with no extra component.
The program counts the pulses on the RB0 pin during 1 second, and send the result to a software emulated serial communication line on RB1 and RB2.
Each level transition from 0V to +5V on the RB0 pin triggers a software interrupt, which increments the cntr counter.
We only have to wait 1 second to know how much times the counter has been increased, this will give us directly the signal frequency.
A simple delay loop with Delay_ms(1000) will not be accurate enough. When interrupts are enabled, like in our case, the delay function lasts longer than expected, that's why we will have to find another way to wait 1 second :
A timer is started at the beginning of each mesure, its overflow will produce another software interrupt, which will increment the ovrflw counter.
When the counter rises to the number corresponding to one second delay, the interrupts are disabled and the cntr counter is converted to string and written to the serial communication line. A new reading cycle is then started.
This simple frequency meter will give a 1 Hz accuracy in the range from 1 Hz to 67 KHz approximately with a 16 MHz crystal.
The maximum frequency depends on the speed of the microcontroller : with a 20 Mhz clocked pic, the maximum frequency range should be around 83 KHz.
You can also make it run with a high-speed PIC : 40 MHz or 48 MHz, which should allow more than 160 KHz.
The limitation comes from the interrupt routine : have a look on the asm file produced by the MikroC compiler, you will see that around 60 clock cycles are needed to complete the call. If the transitions on the RB0 pin are too fast, they will overlap, and the cntr counter will not be incremented at each edge.
If you need higher frequency range, just add a cheap decade counter like the 4017 : it will multiply by 10 the maximum frequency range, but you will lost the last significiant digit.
Add another divider if you want to multiply it by 100, or a programmable divider : you have enough free I/O pins on the pic to control it.
Here is the ultra simple code for MikroC compiler :

DCF77 LED Clock C Source Code | Microcontroller Project

/*
* DCF-77 LED CLOCK
*
* PIC16F84A
* 10 Mhz crystal, HS clock
*
* PORTA.0->3, out : 7 segment cathod control
* PORTA.4, in ; DCF pulse input
*
* PORTB.0->7, out : 7 segment output
* PORTB.7, in : button input
*
* Author : Bruno Gavand, november 2005
* see more details on www.micro-examples.com
*
*/

/*
* constant definitions
*/
#define MAXCOUNT 9766 // number of TMR0 overflows in 1 second
#define ADJUST 96 // extra ticks in 1 second

/*
* this values are reduced in practice
* to give some flexibility to DCF-77 pulse reception
*/
#define timer_d_min 14000 // number of TMR0 overflows in 2 seconds : 19531
#define timer_h_0 640 // number of TMR0 overflows in 0.1 second : 976
#define timer_h_1 1400 // number of TMR0 overflows in 0.2 second : 1953 more..........

DCF-77 PIC LED clock | Microcontrollers Project

1. What is DCF77 ?

DCF77 is the name of a german radio station on 77.5 KHz, which gives official time and date from an atomic clock located in Francfort. The time and date is coded into a 59 bit length frame, and is sent on the air through an antenna, by a 50 kilowatt power amplifier.
A simple and tiny receiver can catch the signal, from approximately 2000 kilometers around the antenna. The pulse contained in the radio frequency signal is filtered by the receiver : a 100 ms pulse is a value of 0, a 200 ms pulse is a value of 1, there is a pulse per second, and the last second of a minute lacks (there is 2 seconds without pulse) to allow synchronisation with the next minute.
There are many good web sites about DCF77, I strongly recommend to visit the official DCF77 web site :
it contains all that you have to know about DCF-77. You can also try a Google search on DCF77 and select the most appropriate result for your convenience.

Introduction to Operations Research

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HYDRAULIC CONDUCTIVITY: The Peremeater

DEFINITION :


The hydraulic conductivity of a soil is a measure of the soil's ability to transmit water when submitted to a hydraulic gradient. Hydraulic conductivity is defined by Darcy's law, which, for one-dimensional vertical flow, can be written as follows:



where U is Darcy's velocity (or the average velocity of the soil fluid through a geometric cross-sectional area within the soil), h is the hydraulic head, and z is the vertical distance in the soil. The coefficient of proportionality, K, in Equation 5.1 is called the hydraulic conductivity. The term coefficient of permeability is also sometimes used as a synonym for hydraulic conductivity. On the basis of Equation 5.1, the hydraulic conductivity is defined as the ratio of Darcy's velocity to the applied hydraulic gradient. The dimension of K is the same as that for velocity, that is, length per unit of time (IT^-1).


Hydraulic conductivity is one of the hydraulic properties of the soil; the other involves the soil's fluid retention characteristics. These properties determine the behavior of the soil fluid within the soil system under specified conditions. More specifically, the hydraulic conductivity determines the ability of the soil fluid to flow through the soil matrix system under a specified hydraulic gradient; the soil fluid retention characteristics determine the ability of the soil system to retain the soil fluid under a specified pressure condition.

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Fundamentals of Thermodynamics

Fundamentals of Thermodynamics 

Lecture #1, Introduction, laws of thermodynamics, notation. 

Lecture #2, work and Progress 

Lecture #3, First and second laws. 

Lecture #4, Gibbsian equations, chemical potential.

Lecture #5, Mathematical methods, Legendre transforms.

Lecture #6, Partial derivative game.

Lecture #7, Process evaluation. Residual functions.

Lecture #8, Residual functions and example problems.

Lecture #9, Introduction to statistical mechanics and quantum mechanics.

Lecture #10, Quantum mechanics I.

Lecture #11, Quantum mechanics II.

 

Check out This link for a description of the rotational energy of a molecule.

 

Lecture #12, Statistics and ensembles.

Lecture #13, Ensembles and partition functions.

Lecture #14, Semi-classical partition function.

Lecture #15, Properties of ideal gases.

Lecture #16, Properties of ideal gases, examples.

Lecture #17, Chemical equilibria: ideal and real fluids.

Lecture #18, Pair potentials and nonideal behavior.

Lecture #19, Conformal solution theory.

Lecture #20, Conformal solution theory, pure fluids and mixtures.

Lecture #21, Ideal solutions and partial molar quantities. 

Lecture #22, Partial molar properties and fugacity.

Lecture #23, Local composition models

Lecture #24, Mixture thermodynamics calculations.

Lecture #25, Local compositions.

Review.

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Rotational energy of a molecule (Description)

How do we know the bondlength for CO, for example, is 112.83 pm? One technique among many is the application of "rotational spectroscopy." In this method, electromagnetic radiation from the microwave region of the spectrum, is absorbed by a molecule causing the molecule to rotate faster. The wavelength or wavenumber or frequency of the microwave photon absorbed is related to the difference in energy of the molecule before and after absorbtion (as you know). In this case, the energy is rotational energy.

The classical energy of a rotation body depends on how the mass is distributed about the center of rotation. CO would be treated as a barbell shape as pictured below. The "bond" itself would have zero mass, the mass of the carbon atom would be 12.0000 (if the carbon were ¹²C) and that of the oxygen would be 15.9949 (if it were ¹⁶O) mass units. We can abbreviate these masses now as m₁₂ and m₁₆.

Notes on Thermal Physics

Notes on Thermal Physics 

• Diagrams of Stirling engine. 

A Stirling engine is a heat engine operating by cyclic compression and expansion of air or other gas, the working fluid, at different temperature levels such that there is a net conversion of heat energy to mechanical work

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• Summary of the Thermal Physics

 Thermal physics, generally speaking, is the study of the statistical nature of physical systems from an energetic perspective. Starting with the basics of heat and temperature, thermal physics analyzes the first law of thermodynamics and second law of thermodynamics from the statistical perspective, in terms of the number of micro states corresponding to a given macro state. In addition, the concept of entropy is studied via quantum theory.

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• Solutions to the Final Examination

• Problem Set 1.

• Problem Set 2.

• Problem Set 3

• Problem Set 4.

• Problem Set 5.

• Problem Set 6.

• Problem Set 7. 

• Solutions to Midterm Examination.

• Introduction and Notes on Fluids

• Notes on Temperature

• Notes on Heat and the First Law

• Notes on Kinetic Theory

• Notes on the Second Law

• Notes on Entropy 

 Entropy is a thermodynamic property that is a measure of the energy not available for useful work in a thermodynamic process, such as in energy conversion devices, engines, or machines. Such devices can only be driven by convertible energy, and have a theoretical maximum efficiency when converting energy to work. During this work entropy accumulates in the system, but has to be removed by dissipation in the form of waste heat.

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Thermodynamic Formulas | Chemical Engineering

Thermodynamic Formulas:

 

Piping Systems Manual

Introduction to Power Electronics notes

Introduction_to_Power_Electronics_notes

Introduction to Power Electronics

Low Impact Development Technique

Concrete Foundation and Slab Inspection

Concrete Foundation and Slab Inspection

builders foundation handbook