Bidirectional datatransfer of Keyboard HELP HELP EMERGENCY !!!!!!!!!!!!!!!!!!!!!!!!!!

[harpre]

I am working on the wireless keyboard. In keyboard with PS-2 protocol there are two lines data and the clock lines. Both of these lines are the bidirectional lines. I am planning to have a keyboard and then connect it to the microcontroller and then to the transreciever. Similarly on the CPU side also.


I am working with 89C51 microcontroller. I have connected these clock and data lines to any of the port pins acting as the Input and the outport. In clock line when i am using it as output line at the same instant there can be a signal input to the port of the microcontroller from the CPU which cannot be predicted except detecting it at regular intervals. But by doing this it takes lot of time which might be required for execution of some data transfer taking place somewhere else. Even i cannot use the Interrupt for the regular interval checkup for the same reason of time. So if i can get this clock line and make some arrangements such that if the input signal from CPU comes it would be diverted to some other pin and if a output signal wants to be send on the same clock line then it would be send via different pin.

For that i have founded circuit for the same wireless keyboard with the use of the AVR microcontroller Atmeg32. This circuit shows the arrangement that by connecting the 510 ohm resistor between the 2 pins of the port one can act as the input while the other can as an output. The circuit diagram can be found on this link

https://instruct1.cit.cornell.edu/courses/ee476/FinalProjects/s2003/lph2/WirelessKybd/index.html


I wanted to know that is the similar arrangement possible with the 89C51 microcontroller also.

Also please please reply let me know that if this is not possible is there any such arrangement possible with any other IC or anything else also??????


PLEASE REPLY SOON ITS REAL EMERGENCY...........................................................

 

[ericgibbs]

hi,
I have seen this method used on other PIC's OK.

Ive been searching my library for a sample image, no luck.

From memory the input pin is the pin connected to the junction of the outgoing wire and the resistor.
The driving output is the pin with just the resistor.

As you probably know the data and clock are high at rest for the AT keyboard. Pull low is active state.

Hope this helps
EricG

 

[justDIY]

is it an emergency, as in, a terrorist has a gun to your head, your life is in jeopardy and if you don't get your keyboard gizmo working it's curtains?

or is an emergency, as in, you've waited to the last minute to start your final project?

 

[ericgibbs]

hi justdiy,

Its all gone quiet. I didn't hear a bang?, perhaps its just the final curtain.

Eric

 

[justDIY]

Eric,

My guess is "harpre" had to run to class, or perhaps is off posting the question to other forums ... maybe they are getting some text books from professor or library to figure it out the old fashioned way!

 

[harpre]

Keyboard

hi people i have been working on the programming of it and still have time till april end. But i believe this is the way i should work on otherwise it will be hard to complete it. Any way thanks for your reply but still can u confirm that it has worked on PICs and AVRs so that i can carry on my programming in this way. Thanks for reply.

 

[House0Fwax]

Typing 'Keyboard interface pic' into Google brought this up.

https://www.electronic-engineering.ch/microchip/projects/keyboard/v1xx/keyboard_v1xx.html

Emergency over ?