# What's the output type of a keypad and how to get 8 bit binary data from keypad?

1. ## What's the output type of a keypad and how to get 8 bit binary data from keypad?

1)what's the output type of a Keypad?
2)How can i get 8 bit binary data from keypad?

•

2. ## Re: 2 questions...

If you are referring to the PS/2 keyboard:

All data is transmitted one byte at a time and each byte is sent in a frame consisting of 11-12 bits. These bits are:
• 1 start bit. This is always 0.
• 8 data bits, least significant bit first.
• 1 parity bit (odd parity).
• 1 stop bit. This is always 1.
• 1 acknowledge bit (host-to-device communication only)

http://www.computer-engineering.org/ps2protocol/
http://www.computer-engineering.org/ps2keyboard/

Please don't overlook the "Helped Me" button

•

3. ## 2 questions...

what in case of other keyboard?

•

4. ## Re: 2 questions...

I want for this keypad how it's output be..in binary form or what else..
What i want is to input two 8 bit number through keypad then those 8 bit number converted in binary form and go to adders and other circuit..
so what i need to do ? if the output of keypad is binary then it's not to difficult..
but if it is something else..then it is..

so plz tell me?

5. ## Re: 2 questions...

For the key board shown there will be total 8 wires coming out, 4 (say C1,C2,C3,C4) for 4 columns and 4 (say R1,R2,R3,R4) for 4 rows. To know which key is pressed first the the s/w will check the lines R1,R2,R3,R4 and then it will check the lines C1,C2,C3,C4. So if key 1 is pressed for first scan I will get a value of 0001( or 1110 based on the hardware circuitry present) and for second scan I will get 0001. Now thru s/w logic you can know which key is pressed.

so the outout is binary, but is 4-bit output.

•

6. ## Re: 2 questions...

Hi...!

Actually these days all peripheral devices (i/o) devices are comming with inbuilt microcontrollers, sothat there is very little burden on the CPU to process their interupts. if your application requires an input from keyboard use more prototypes avilabe in market for quitea lesser price and very simple to use..

all the best..!!

sai

7. ## Re: 2 questions...

Originally Posted by ivar4ever
For the key board shown there will be total 8 wires coming out, 4 (say C1,C2,C3,C4) for 4 columns and 4 (say R1,R2,R3,R4) for 4 rows. To know which key is pressed first the the s/w will check the lines R1,R2,R3,R4 and then it will check the lines C1,C2,C3,C4. So if key 1 is pressed for first scan I will get a value of 0001( or 1110 based on the hardware circuitry present) and for second scan I will get 0001. Now thru s/w logic you can know which key is pressed.

so the outout is binary, but is 4-bit output.
thank u...
well i have few more question ...
basically i have to input two numbers in decimal form whose binary equivalent will not exceed from 8 bit..
so as u said the output is of 4 bit so how can i have 8 bit output...
also i have to enter a numbers lets say 15 wheni hit so how can be the output ?..
is it first show me the 1 and then five or at a time of 15...

plz i am waiting for ur answer.....

--[[ ]]--