Simple Counter with PIC16F877A

Config Proteus like this

And here is the source code

;; -----------------------------------------------------------------------------
;; File name: 7SegmentsLedx4_Counter.asm
;; Email: dmtmd2010@yahoo.com.vn
;; Blog: tdmblogging.blogspot.com
;; Date: March 3rd, 2014
;; Description: a simple counter from 0000 to 9999 using PIC16F877A and 7 segments leds.
;; -----------------------------------------------------------------------------

include P16F877A.inc

; define constants

num_0 equ  20
num_1 equ  21
num_2 equ  22
num_3 equ  23

time_delay  equ  24
time_delay1  equ  25
time_delay2  equ  26

counter  equ  27
rate  equ  28
tmp   equ  29


org 0
goto 100

org 10
table ; look up for 7 segments code
movfw counter
addwf PCL
retlw H'3F'  ; 0
retlw H'06'  ; 1
retlw H'5B'  ; 2
retlw H'4F'  ; 3
retlw H'66'  ; 4
retlw H'6D'  ; 5
retlw H'7D'  ; 6
retlw H'07'  ; 7
retlw H'7F'  ; 8
retlw H'6F'  ; 9

org 100
start
; config and init ports
bsf  STATUS, 5    ; select bank 1

clrw
movwf TRISB    ; mark port B as an output port
movwf TRISC    ; mark port C as an output port

bcf  STATUS, 5    ; select bank 0

clrf PORTB
clrf num_0
clrf num_1
clrf num_2
clrf num_3
clrf rate

movlw H'FF'
movwf PORTC

; main program start here
loop
; control the counting speed
incf rate   ; increase rate
btfsc rate, 6   ; if rate equals 01000000
call incNum0   ; do count
btfsc rate, 6   ; and then clear rate
clrf rate

call display   ; scan the leds
goto loop


display
bsf  PORTC, 0   ; port C equals 11111111

movf num_0, w   ; look for the 7 segments code of num_0 value
movwf counter
call table
movwf PORTB   ; display to port B
bcf  PORTC, 3   ; port C equals 11110111
call delay

bsf  PORTC, 3

movf num_1, w
movwf counter
call table
movwf PORTB
bcf  PORTC, 2
call delay

bsf  PORTC, 2

movf num_2, w
movwf counter
call table
movwf PORTB
bcf  PORTC, 1
call delay

bsf  PORTC, 1

movf num_3, w
movwf counter
call table
movwf PORTB
bcf  PORTC, 0
call delay
return

incNum0
incf num_0   increase num_0
; test if num_0 equals 10 (1010 in binary)
clrf tmp
btfsc num_0, 1   ; xxxxxx1x
bsf  tmp, 0
btfsc num_0, 3   ; xxxx1xxx
incf tmp
btfsc tmp, 1
call incNum1   ; num_0 = 10 -> increase the next
return

incNum1
clrf num_0
incf num_1
clrf tmp
btfsc num_1, 1
bsf  tmp, 0
btfsc num_1, 3
incf tmp
btfsc tmp, 1
call incNum2
return

incNum2
clrf num_1
incf num_2
clrf tmp
btfsc num_2, 1
bsf  tmp, 0
btfsc num_2, 3
incf tmp
btfsc tmp, 1
call incNum3
return

incNum3
clrf num_2
incf num_3
clrf tmp
btfsc num_3, 1
bsf  tmp, 0
btfsc num_3, 3
incf tmp
btfsc tmp, 1
clrf num_3
return

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
delay
movlw H'5'
movwf time_delay2
delay3
movlw H'5'
movwf time_delay1
delay2
movlw H'5'
movwf time_delay
delay1
decfsz time_delay
goto delay1
decfsz time_delay1
goto delay2
decfsz time_delay2
goto delay3
return

END

Textbox with placeholder by C#

It's here. A textbox with placeholder. Look like input control in html. Create a file named STextBox.cs and paste this code:

// -----------------------------------------------------------------------------
// File name: STextBox.cs
// Author: Smart Goat
// Email: dmtmd2010@yahoo.com.vn
// Blog: knowledgesharez.net
// Date: 2013-12-09
// Description: a text box with placeholder, similar the web input control.
//   - Properties:
//      + Placeholder: string - The content of the placeholder
//   - Methods:
//      + IsEmpty(): bool - Check if the text box is empty (recommended)
// -----------------------------------------------------------------------------

using System;
using System.Drawing;
using System.Windows.Forms;

namespace FooBar
{
    class STextBox : TextBox
    {
        private bool textInputted;
        private Color backupForeColor = Color.Empty;
        private string placeholder = string.Empty;

        public string Placeholder
        {
            get { return placeholder; }
            set
            {
                placeholder = value;
                SetPlaceHolder();
            }
        }

        public bool IsEmpty()
        {
            return string.IsNullOrEmpty(Text) || !textInputted;
        }

        private void SetPlaceHolder()
        {
            if (string.IsNullOrEmpty(Text))
            {
                Text = placeholder;
                ForeColor = Color.Gray;
                textInputted = false;
            }
        }

        protected override void OnTextChanged(EventArgs e)
        {
            base.OnTextChanged(e);
            textInputted = !string.IsNullOrEmpty(Text);
        }

        protected override void OnEnter(EventArgs e)
        {
            base.OnEnter(e);
            if (!textInputted)
            {
                Text = string.Empty;
                ForeColor = backupForeColor;
            }
        }

        protected override void OnLeave(EventArgs e)
        {
            base.OnLeave(e);
            SetPlaceHolder();
        }

        protected override void OnForeColorChanged(EventArgs e)
        {
            base.OnForeColorChanged(e);
            if (backupForeColor == Color.Empty)
            {
                backupForeColor = ForeColor;
            }
        }

        protected override void OnKeyDown(KeyEventArgs e)
        {
            base.OnKeyDown(e);
            if (e.Control && e.KeyCode == Keys.A)
            {
                SelectAll();
            }
        }
    }
}

Simple photoshop script

This is my simple script to join images using photoshop:

// create a new document size 30000x500 pixels at 72ppi
var doc = app.documents.add (30000, 500, 72);

// prepare the real width of the joined image
var wid = new UnitValue(0, "px");

// loop through all images
// 3 is the number of images
// images are store in c:\img folder
// images' file name: img1.jpg, img2.jpg, ...
for (i = 1; i <= 3; i++) {
    // take a file
    var fileRef = File("C:\\imgs\\img" + i + ".jpg");

    // open the image in a new document
    var imgdoc = app.open(fileRef);

    // resize the opened image to height 500px
    var ws = 500 * imgdoc.width / imgdoc.height;
    imgdoc.resizeImage(ws, 500);

    // copy the resized image to working document
    imgdoc.selection.selectAll();
    imgdoc.selection.copy();
    app.activeDocument = doc;
    doc.paste();

    // get the top layer
    var pslayer = doc.layers[0];

    // move the pasted image to the right position
    var position = pslayer.bounds;
    position[0] = wid - position[0];
    position[1] = 100 - position[1];
    pslayer.translate(position[0], -position[1]);

    // close the opened image and update the real width
    app.activeDocument = imgdoc;
    wid += imgdoc.width;
    imgdoc.close(SaveOptions.DONOTSAVECHANGES);
}

How the gearbox work

This is how the gearbox work:

[Tutorial] Move form with no border

Just add the below snippet to your code (C#):

private const int WM_NCHITTEST = 0x84; // Mouse capture.
private const int HTCLIENT = 0x1;      // Client area.
private const int HTCAPTION = 0x2;     // Title bar.

// This function intercepts all the commands sent to the application.
// It checks if user click (WM_NCHITTEST) on the form area (HTCLIENT)
// It fakes the result as the title bar (HTCAPTION)
// This makes the form thinks user clicked on the title bar.
// So we can click and move form by (fake) title bar.
protected override void WndProc(ref Message message)
{
    base.WndProc(ref message);

    if (message.Msg == WM_NCHITTEST && (int)message.Result == HTCLIENT)
    {
        message.Result = (IntPtr)HTCAPTION;
    }
} 

[Tutorial] Add offline javadoc to eclipse

If you are working with eclipse, the javadocs come from internet. And eclipse takes a bit delay to show the docs. You can config your eclipse to use offline javadocs. This will make eclipse faster and you can see the docs without internet. These are the step:
1. Download javadocs:
Java 6: http://docs.oracle.com/javase/6/docs/
Java 7: http://docs.oracle.com/javase/7/docs/
Download the javadocs zip file and put in any where that you want.
2. Config eclipse:

Select Preferences

Select Installed JREs

Select the java version that you want to add docs and then select Edit

Select rt.jar package and then select Javadoc Location

Select Javadoc in archive and browse the zip that you downloaded

Done

How the CPU works

Every computer, smartphone, ... has a CPU inside. It's the brain of these devices. But how it works? After surfing around for a while, I found this. Take a look at how a CPU works:

Summary:
First, all devices have their own machine code to tell them what to do.
CPU takes a string of bits (machine code - designed by the manufacturer) and output another string of bits that do some special tasks or tell the devices what to do.
'The strings of bits' - intructions, are stored in RAM (random access memory). CPU read (input) these instructions and execute an output. The output maybe tell the hard disk to write somethings. Maybe store somethings to RAM again.