Monday, July 12, 2010
Interfacing the Keyboard to 8051 microcontroller.
When ever a key is pressed, a row and a column gets shorted through that pressed key and all the other keys are left open. When a key is pressed only a bit in the port goes high. Which indicates microcontroller that the key is pressed. By this high on the bit key in the corresponding column is identified.
Once we are sure that one of key in the key board is pressed next our aim is to identify that key. To do this we firstly check for particular row and then we check the corresponding column the key board.
To check the row of the pressed key in the keyboard, one of the row is made high by making one of bit in the output port of 8051 high . This is done until the row is found out. Once we get the row next out job is to find out the column of the pressed key. The column is detected by contents in the input ports with the help of a counter. The content of the input port is rotated with carry until the carry bit is set.
The contents of the counter is then compared and displayed in the display. This display is designed using a seven segment display and a BCD to seven segment decoder IC 7447.
The BCD equivalent number of counter is sent through output part of 8051 displays the number of pressed key.
to check that whether any key is pressed
start: mov a,#00h
mov p1,a ;making all rows of port p1 zero
mov a,#0fh
mov p1,a ;making all rows of port p1 high
press: mov a,p2
jz press ;check until any key is pressed
after making sure that any key is pressed
mov a,#01h ;make one row high at a time
mov r4,a
mov r3,#00h ;initiating counter
next: mov a,r4
mov p1,a ;making one row high at a time
mov a,p2 ;taking input from port A
jnz colscan ;after getting the row jump to check
column
mov a,r4
rl a ;rotate left to check next row
mov r4,a
mov a,r3
add a,#08h ;increment counter by 08 count
mov r3,a
sjmp next ;jump to check next row
after identifying the row to check the colomn following steps are followed
colscan: mov r5,#00h
in: rrc a ;rotate right with carry until get the carry
jc out ;jump on getting carry
inc r3 ;increment one count
jmp in
out: mov a,r3
da a ;decimal adjust the contents of counter
before display
mov p2,a
jmp start ;repeat for check next key.
Saturday, July 10, 2010
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Saturday, April 3, 2010
Wednesday, March 24, 2010
Tuesday, March 2, 2010
Monday, March 1, 2010
"The Avianca Flight 52 accident"
"I was totally dis hearted, when I saw the show on The Avianca Flight 52 accident on a popular channel. Avianca Flight 52 was a regularly scheduled flight from Bogotá to New York's John F. Kennedy International Airport via Medellín, Colombia's José María Córdova International Airport."
"On Thursday, January 25, 1990, the aircraft performing this flight, the Boeing 707-321B registered as HK-2016, crashed into the village of Cove Neck, Long Island, New York after running out of fuel. 8 of 9 crew members and 65 of 149 passengers on board were killed."
Accident summary
Date: January 25, 1990
Type: Fuel exhaustion and pilot error
Site: Cove Neck, New York
Passengers: 149
Crew: 9
Injuries: 85
Fatalities: 73
Survivors: 85
Operator: Avianca
Flight origin: El Dorado International Airport
Stopover: José María Córdova International Airport
Destination: John F. Kennedy International Airport
Source - wikipedia
for more info visit: http://en.wikipedia.org/wiki/Avianca_Flight_52
"May such accidents never ever happen again."
Sunday, February 28, 2010
"The basic comes from - Static electricity"
As I was going through the basics of electronics, I wondered from where did the evolution of electronics came from. Then I got this site which explained to me, (not deeply mentioned in any of the books) about the importance of Static electricity. Static electricity is a beautiful phenomena to learn. The basic of electronics comes from Static electricity !
visit - http://www.learningelectronics.net/ ,you will find all the terms related to electronics needed to clear your basics, as I did so!
Saturday, February 27, 2010
"Maha Krishna said...."
Maha Krishna said,
"Whatever has happened, has happened for good.
Whatever is happening, is also for good.
Whatever will happen, shall also be good
What have you lost, that you cry for?
What did you bring, that you have lost?
What did you create that you have destroyed?
What you have taken, has been form here.
What you gave, has been given here.
What belongs to you today, belonged to someone yesterday,
Shall belong to third person day after,
So why worry unnecessarily? Change is the law of universe."
"Lord Krishna said..."
"Your right is to work only,
But never to it's fruits;
Let not the fruits of action be thy motive,
Nor let thy attachment be to inaction."
Saturday, February 20, 2010
"Check out Save Our Tigers | Join the Roar"
Link: http://gotaf.socialtwist.com/redirect?l=316546803632731638221
"From around 40,000 at the turn of the last century, there are just 1411 tigers left in India. What started as a Royal Sport during the olden times is now a target of Poaching and Depleting Habitat. Our National Animal is fighting for its life! The rich biodiversity and natural capital of India can be witnessed in the Tiger Sanctuaries."
"Knowledge of these sanctuaries helps build awareness for the cause."
"From around 40,000 tigers at the turn of the last century, there are just 1411 tigers left in India. 2009 was the worst year for tigers in India, with 86 deaths reported.There are 37 Tiger sanctuaries in India. However, 17 sanctuaries are on the verge of losing their tiger population."
"Corbett National Park is the oldest tiger park in India. It was created in 1936 as ‘Hailey National Park’.The Kanha National Park’s lush sal and bamboo forests, grassy meadows and ravines provided inspiration to Rudyard Kipling for his famous novel, The Jungle Book."
"A small contribution will help save our national animal !"
click to enlarge the picture
Friday, February 19, 2010
"miniProject - a battery-eliminator-circuit"
"This is a great mini project to generate 9V dc supply as a linear PSU."
"This battery eliminator circuit can be used as a replacement for 9V PP3 batteries. The circuit given here can be used to power any device that operates from a 9V battery. The transformer T1 steps down the mains voltage and bridge D1 performs the job of rectification. Capacitor C1 is a filter. IC LM317T is the regulator here. The value of R1, R2 and R3 are so selected that the output voltage of IC1 will be steady 9 volts."
"But people here are some of the important notes that one must take care."
"Note-
Assemble the circuit on a good quality PCB.
Transformer T1 can be a 230V primary, 9V secondary, 1.5A step down transformer.
If 1A Bridge is not available, then make one using four 1N 4007 diodes.
Do not connect loads that consume more than 1.5A to this circuit.
A heat sink is recommended for IC1."
Thursday, February 18, 2010
"Lord Krishna is the King of this universe !"
"He is my king:He is my Gem!"
"I was here because of him,I am here because of him,and I will be here because of him !"
"He is the supreme soul,he is the father of all,he is the perfect,his persona is infinite,his thoughts are most beautiful of all and I only desire him! Let the world live happily, and let there be peace. Let us get mukti and onto his lotus feet."
Wednesday, February 17, 2010
"Fabregas is the best of the best"
"I have been a die heart fan of Arsenal Football Club ever since I started my football career. Watching them play every week- end became a part of my time-table."
"The kind of football they play is too different in terms of passing, passing and more passing, and not being selfish to score like the others. Their young talented attacking midfield leaded by their captain Csec, and a beautiful approach towards the opponents goal is surely a rare sight among other big clubs."
"Arsenal's Francesc Fàbregas i Soler, formly known as Csec Fabregas is the best of the best among the rising young midfielders. He Started his Youth career as a midfield player in Mataró and Barcelona. Joining Arsenal in 2003, the star initially played as a defensive midfielder. Sensing that he would have limited opportunities at Barcelona he joined Arsenal, and this was the turning point for us. Now the no.4 is the captain of our team, roaming around the attacking side of the field, trying to score with his venomous strikes and beautiful passing."
"INE - my worst paper given in 3 years"
Friday, February 12, 2010
"Now comes the memory part"
"The motherboard has several specs that will tell you what the optimal memory component is. There are usually several differences, but they generally fall into these categories:
1.RD RAM, also known as Rambus RAM, is pretty expensive (per megabyte) versus other types of RAM and is generally not used in the consumer market, although you may see it in higher-end motherboards.
2.DDR, DDR2, DDR3 are the more common types of RAM. DDR is an outdated technology. DDR2 is the current standard, but that is slowly being replaced with DDR3. While DDR3 is the latest technology, its performance isn't currently up to par with the top of the line DDR2 (but this will change pretty quickly!)."
"Check your motherboard specs - it should list four important pieces of information:"
"Memory type, which is RDRAM, DDR, DDR2, or DDR3. If it's another type, you've either bought a high-end server motherboard or a really old motherboard.
Memory speed, which is typically represented in MHz. common speeds include 500, 600, 667, 1033, etc...
Memory size, which represents the amount of memory your particular motherboard supports. This is usually represented in GB (Gigabytes) as 1, 2, 3, 4, 16, 32, etc... Currently, 4GB and 8GB are the standard, but 16GB and 32GB standards are not far behind. Number of modules tells you how many sticks of RAM can be used.
Typically a motherboard will hold anywhere from 1 to 4 sticks of RAM (and some high-end server motherboards can support upwards of 32 sticks of RAM!)"
"-But remember,PC will support the maximum memory module size (eg.1 GB,2 GB) as, the maximum capacity the system can take (eg.my motherboard can take maximum 2 GB of ram) divided by, the maximum number of slots (2 DIMM slots in my case)."
"Max. RAM piece = 2 GB/2 slots
Max. RAM piece = 1 GB
So i have connected two 512 MB RAM in my 2 slots. I can connect max. 1 GB (as per calculations) of ram in each slot ( 2 slots), of the 2 GB max. supported by my motherboard."
Thursday, February 11, 2010
"Choose compatible processor with the right motherboard"
"There are some of the important things to consider for selecting the proper CPU according to the motherboard- "
1.check the socket type of board - socket 448,socket T6600 etc. for intel processors and AM2,Am2+,AM3 etc. for AMD processors.
2.check the clock frequency of board - eg.1600/1333/1066/800etc. FSB should be compatible with the processor.
3.check the proper label (I do not know what it is called),please check the specification list.It will be given as, for eg."Processor Types : AMD Phenom II X3, X4 (X4 810) as writen for Gigabyte GA-790FXTA-UD5 Motherboard manual."
"I only found these main rules while studying. And sometime later I will surely try to virtually assemble - a motherboard,CPU and graphic card with the right compatibility soon and post it too."
"This would be a powerfull system"
"This system is just an example composition towards the compatibity learning procedure of assembling a new PC."
Motherboard : Gigabyte GA-790FXTA-UD5 Motherboard
Supporting AM3+DDR3+USB 3.0 and SATA 3.0 using the 790FX chipset.
Marvell SE9128 SATA3 interface
AM3 CPU Support
Advanced 8+2 phase CPU VRM power design
Dual Channel DDR3 1866+
3 PCI-E 2.0 x16 graphics interface
Socket Socket AM3
Memory speed 1866 (OC)/1600/1333/1066/800 DDR3
Processor Types AMD Phenom II X3, X4 (X4 810)
Memory Type DDR3
Memory Channels Double
Maximum Memory 16GB
External Graphics PCI Express x16 x3
IGP N/A
IDE 133/100/66
SCSI None
SATA 6.0 GB/s
Form Factor : ATX
"..We can also choose the AMD Phenom II X3 processors, but I choose the X4, not much price difference though."
Processor : AMD Phenom II X4 810 Deneb, 2.6GHz, 4 x 512KB L2 Cache, 4MB L3 Cache, Socket AM3, 95W Quad-Core Processor
"...And any of the Graphic video card:"
Radeon HD 4670 Video Card (1GB, PCI-Express 2.0 x16, Dual DVI)
Radeon HD 4670 1.0 GB SDDR3 HDMI (HD-467X-DDF2)
Radeon HD 4670 1GB DDR2 (HD-467X-ZDQ7)
"..and any other compatible Graphic video card device...
I will be taking the memory (RAM) into consideration the next time"