Electronics EveryWhere: September 2009

Saturday, September 19, 2009

PIC16F84A Clock

Description:

This is a simple clock that uses PIC16F84A ucontroller,4050 CMOS, seven segment (common anode), and few other components.

Short the same pins of 7-segment (a with a, b with b and so on) and connect them with appropriate 4050 pin. Also make sure to invert D3 & D4 like this:

7-Segment CA pin out:

Schematic:

click on image to zoom

Top:

Bottom:

Components:

IC3 PIC61F84A
IC1 & IC2 Cmos 4050
Resistors, R1 - R3 10K ohm 0.25W
S1 - S2, Push Switches
Ceramic Capacitors,C1-C2 30pF
Q1 4 MHz Crystal
D1-D4 seven segment CA

Friday, September 11, 2009

This schematics is of dual power supply, having voltage output 3,5,6,9,12,15 and -3,-5,-6,-9,-12,-15. LM 317 is adjustable 3-terminal positive voltage regulator and LM 337 is adjustable 3-terminal negative voltage regulator.

Switch S1 is for +ve and S2 is for -ve voltage respectively.

Schematic:

click on image to zoom

Pin out:

Components:

All diodes are 1N4007

R1, R3 270 ohm

R2 1K2 ohm

R4, R10 390 ohm

R5, R11 820 ohm

R6, R12 1K ohm

R7, R13 1K65 ohm

R8, R14 2K35 ohm

R9, R15 3K ohm

LM317T

LM337T

C5, C8 2200uF 25v electrolyte

C6, C7, C9, C10 22uF 25v electrolyte

C1-C4 0.1uF Ceramic

F1 0.5A fuse

S Switch

S1, S2 6-way rotary switch

T1 Center taped transformer 15-0-15v 220v

Red LED

Friday, September 4, 2009

Parallel Port Interfacing

A parallel port is a type of socket found on personal computers for interfacing with various peripherals. It is also known as a printer port.

PC parallel port is 25 pin, D-shaped female connector in the back of the computer. Not all 25 are needed always. Usually you can easily do with only 8 output pins (data lines) and signal ground.

The original IBM-PC’s parallel port had a total of 12 digital outputs and 5 digital inputs accessed via 3 consecutive 8-bit ports in the processor’s I/O space.

Pin out:

Pin description:

You can not directly access the parallel port in windows xp, vista etc due to the security purpose. To access the port do the following:

1. first go to the BIOS setting.

2. then select advanced option.

3. under this option select peripheral configuration

4. then change the setting of parallel port as

a. enable

b. bi-diractional

c. IRQ-7

After doing these steps download the user port and follow the instructions. A window will open, when you will run userport.exe, asking the range.

To find this:

right click on my computer icon
select manage
from device manager select ports(com &LPT)
double click on printer port
a window will open, choose the resources tab you will find

Fill this range in both the spaces and then click on add button. Then click on start button three times, a message will appear just click ok.

Now your port is ready for interfacing.

Tutorial one:

LED Chaser:

Connect 8 LEDs to the data port of the parallel port as shown in the figure.

Connect ground to pin # 25.
Copy and paste the assembly program link it (in MASM) & create .exe file.
This program is basically LED chaser in which LEDs blink from left to right when you press ‘r’ and from right to left when you press ‘l’. to off these LEDs just press ‘ 0’ and ‘Esc’ button to exit.

Assembly code:

Dosseg

.model small

.stack 100h

.data

msg db 13,10,'Press r for right movement',13,10,'Press l for left movement',13,10, 'Press 0 to Off',13,10, 'Press Esc to exit','$'

.code

main proc

mov ax,@data

mov ds,ax

mov ah,09h

lea dx,msg

int 21h

set: mov al, 0ffh

mov dx, 378h

out dx,al

call delay

mov al,00h

out dx,al

call delay

mov al,10000000b

lop1:

push ax

push dx

mov ah,06h

mov dl,0ffh

int 21h

cmp al,27

je exit

cmp al,'0'

je off

cmp al,'r'

je loop2

pop dx

pop ax

ror al,1

out dx,al

call delay

jmp lop1

loop2:

mov dx,378h

mov al,01h

strt: out dx,al

call delay

rol al,1

push ax

push dx

mov ah,06h

mov dl,0ffh

int 21h

cmp al,27

je exit

cmp al,'0'

je off

cmp al,'l'

je set

pop dx

pop ax

jmp strt

off: mov al, 0h

mov dx, 378h

out dx, al

exit: mov ax, 4c00h

int 21h

main endp

delay proc

push ax

push dx

mov bx,00h

mov ah,2ch ;To Get System Time

int 21h

mov bh,dl ;Copy seconds into bh reg

getsec: mov ah,2ch

int 21h

cmp bh,dl

jne back ;Jump to back when get 1 sec.

jmp getsec

back: pop dx

pop ax

ret

delay endp

end main

Tutorial two:

Seven Segment Common Cathode Counter:

Common Cathode means all –ve terminals of LEDs are grounded & 1 for on, 0 for off.

Connect 8 LEDs to the data port of the parallel port as shown in the figure.

1^st construct the table for 7-segment

Digits	Hex
0	3f
1	06
2	5b
3	4f
4	66
5	6d
6	7d
7	07
8	7f
9	6f

This is basically 7-segment counter & timer in which you can set/reset, and pause it.

If any one interested in this, he can ask me about the assembly code of this project.

Enjoy playing with parallel port.

Electronics EveryWhere

Pages

Saturday, September 19, 2009

PIC16F84A Clock

Friday, September 11, 2009

Dual Power Supply

Friday, September 4, 2009

Parallel Port Interfacing