INTERFACING OF 4x4 KEYPAD TO MICROCONTROLLER

INTERFACING OF 4x4 KEYPAD TO MICROCONTROLLER

• Interfacing of microcontroller to 4x4 Keypad is very simple.
• The Simple logic behind this is just scan all the key in the matrix.
• Let assume 4 line are output and 4 lines are input.
• Columns are input.
• Row are output.

	C1	C2	C3	C4
R1	0	1	2	3
R2	4	5	6	7
R3	8	9	A	B
R4	C	D	E	F

          C = Columns

          R = Rows

Case 0:

	C1	C2	C3	C4
R1	0	1	1	1
R2	1	1	1	1
R3	1	1	1	1
R4	1	1	1	1

•  When Row and Column are shorted then it is accepted as Key Pressed Now C1 & R1 = 0.
• That means “0”. 

Case 15:

	C1	C2	C3	C4
R1	0	1	1	1
R2	1	1	1	1
R3	1	1	1	1
R4	1	1	1	0

•  When Row and Column are shorted then it is accepted as Key Pressed Now C4 & R4 = 0.
• That means “F”.

Similarly all other Keys are checked. While pressed we must wait to 20msec i.e. Debounce effect of switch button or key. If Still key is pressed then it’s assumed as key pressed and Equivalent value is displayed.

Thank you and for any queries do comment .....

For Program download it below link:

For LCD : Click for Code

For Keyboard : Click for code

For Videos on Above Program : Click on the Link

INTERFACING OF LCD IN 4-BIT MODE USING MICROCONTROLLER

INTERFACING OF LCD IN 4-BIT MODE USING MICRO-CONTROLLER

In this method of Interfacing LCD to Microcontroller using 4-bit mode is to reduce the usage of pin.

Mostly the Circuit having multiple function uses this method.

In this method PORT0 of UC is connected to LCD as Follows:

P0.0 => rs;    Register select Pin

P0.1 => en;  Enable Pin

P0.4 => D4;  data line

P0.5 => D5;         “

P0.6 => D6;         “

P0.7 => D7;         “

In method we use same port for control pin as well as data line. So each data is send by breaking it into two 4bit part.

To initialize LCD in this method a command used is 0x28

Which means 16 x 2 LCD in 4-bit mode.

Before doing that we should send a sequence of 0x30, 0x30, and 0x20.

To send this we use only cmd_hf function which send only 3, 3, and 2 as sequence to LCD to enable in 4-Bit mode.

To send each data we should first clear the higher order bit i.e. from P0.4 – P0.7

And masking the input is properly shown in video.

• We should mask Higher bit and rest all bit are clear.
•  We send by latching.
• We should now mask lower bit and send to UC.

This is how a 4-Bit mode LCD works.

Thank you for reading.

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Source Code: click for code

For Videos on this Example: Click on the link

INTERFACING OF MICRO-CONTROLLER 8051 TO ADC (ADC 0804)

 INTERFACING OF MICRO-CONTROLLER 8051 TO ADC (ADC 0804)

Micro-controller 8051 does not has in-built ADC. So, we are using external ADC 0804. It is an 8-bit ADC so, resolution = 8-bit.

ADC 0804 Pin Details:

                            

DB7 - DB0 – Are 8 Data Pin which hold Converted Digital data.

CS - It is an Active low signal usually we can ground it, or use a pin from microcontroller to control it by passing high to low pulse in the pin.

RD – It is an Active low signal it use to read data from ADC0804 Data line (DB7-DB0).

WR - It is an Active low signal. When low to high signal is passed in that pin the adc conversion start.

INTR - It is an Active low signal. It is used to Check for End of Conversion.

Vref/2 – It is the References voltage is given to ADC for Step sizes Calculation of conversion.

AGND – Analog Ground.

DGND – Digital Ground.

Important Note:

Resolution of this ADC is 8bit, so that means the Steps ranges from (0-255)

Formula:

            Step sizes = Vref/(2ⁿ -1);              n = 8(Resolution of ADC).

                            = Vref/(256 - 1);

                                   =  Vref/255;  

• To convert and display the data into LCD we use a formula to convert it to ascii.

                                      if data = 125  

     for unit place data the formula is

•         (data%10) = 5 => now or with 30h we get ascii value i.e.( 5|0x30 ) = 35

                               35 in ascii means 5 numeric.

     for tenth place data the formula is

•          ((data/10)%10) = 2 => now or with 30h we get ascii value i.e.( 2|0x30 ) = 32

                               32 in ascii means 2 numeric.

     for send data the formula is

•        ((data/100)%10) = 1 => now or with 30h we get ascii value i.e.( 1|0x30 ) = 31

                               31 in ascii means 1 numeric.

• To convert the data into LCD in Hex format using lookup table
•  first Mask the low bits using 0xF0 and shift higher 4bit data to lower 4 bit and        get the equal data from lookup table.
•  then, mask the Higher bits using 0x0F and compare it with lookup table and          display it.

                 Ex:

              Higher bits = (data & 0xF0)>>4;

              Lower bits = (data & 0x0F);

• To Convert the Digital data to analog we have formula ie;

                       

                        D_out = V_in/step sizes;

                        So, when we alter it we get

                        V_in = D_{out *} Step size;

                        V_in = D_out * (Vref/2ⁿ-1);

Apply this formula we get input voltage;

Thus we have done the Coding for Interfacing of ADC to 8051. 


Program for ADC:click for code

Video on above Example: Click for videos

SIMPLE INTERFACE STEPPER MOTOR TO 8051

SIMPLE INTERFACE STEPPER MOTOR TO 8051

In this Program we have interface Stepper motor to 8051. Stepper motor is Driven by L293D IC.

L293D IC need Vss = +12V and Vs = +5V and en1 and en2 are used to enable Push-Pull Driver.

In this method we have used A unipolar Stepper motor.

• A unipolar stepper motor has one winding with centre tap per phase. Each section of windings is switched on for each direction of magnetic field. 

• Since in this arrangement a magnetic pole can be reversed without switching the direction of current, the commutation circuit can be made very simple (e.g., a single transistor) for each winding. 

• Typically, given a phase, the centre tap of each winding is made common: giving three leads per phase and six leads for a typical two phase motor. Often, these two phase commons are internally joined, so the motor has only five leads. 

• A micro controller or stepper motor controller can be used to activate the drive transistors in the right order, and this ease of operation makes unipolar motors popular with hobbyists; they are probably the cheapest way to get precise angular movements.

It Work According to the Table given below:

 

A	B	C	D	De
1	0	0	0	45
1	1	0	0	90
0	1	0	0	135
0	1	1	0	180
0	0	1	0	225
0	0	1	1	270
0	0	0	1	315
1	0	0	1	360 or 0

A = in1

B = in2

C = in3

D = in4

De = Degree of rotation

FOR PROGRAM REFER LINK:Click on this link for code

For videos on above example : click on this link