Another PC keyboard interfacing question...

[mcoster]

Hi,

i decided to start playing with my PC keyboard input (PS2) and i want to build a keyboard emulator.

My questions are:

Is it easy to burn the PC (PS2) input port if i do something stupid ?

I read that, since the PS2 is a input and output port it is open colector. Does this means i have to be more carefull or it is more robust or maybe none of the above ?

Since it is open collector and i am using a AT89S52 shuld i connect my uC to the PC using its open collector port ?


that´s all

Thanks a lot
mcoster

 

[computer_terminator]

Most of time you will burn down the inductors between your keyboard and PC chipset.

It would be better to use open collector to PC.

 

[barny451]

You really are best to use an open collector driver such as 7407.

7407 is best also because it is non-inverting. That means that during power-up when your uC has its ports defaulting to high, the 7407 output won't be pulling the lines to the PC low. This is important because the keyboard controller on the PC motherboard checks the clock and data lines aren't low. You could also use two inverters as long as the one driving the PC is open collector.

HTH
Barny

 

[Taro]

You can find some useful information at www.beyondlogic.org