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Update README.md #62

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Expand Up @@ -116,7 +116,14 @@ This is the male connector at the keyboard cable.
<img src="doc/ps2.jpg" width="30%" />
<img src="doc/gpio.png" width="80%" />

Most keyboards seem to work if powered with 3.3V. However if your keyboard does not and needs 5V, make sure you use a bidirectional level shifter between the Raspberry Pi and your keyboard on data and clock. If you bring 5V to the GPIO you will destroy the Pi.
Most keyboards seem to work if powered with 3.3V. However if your keyboard does not and needs 5V, make sure you use a bidirectional level shifter between the
Raspberry Pi and your keyboard on data and clock. If you bring 5V to the GPIO you will destroy the Pi.

It may also be necessary to install a .1uF decoupling capacitor between 3.3v and ground, as close to the PS/2 connector where the keyboard plugs in, to stabilize the
connection to the keyboard. if your keyboard is locking up this may be the issue.  IBM's schematics for the PS/2 Model 30-286 depict a current limiting resistor of
240ohms on the PS/2 Power pin as well as a decoupling capacitor, though with a modern keyboard this might not be necessary.   It's also important to remember that
PS/2 is not hot pluggable.  If you are concerned about hardware damage to your keyboard or Pi computer installing a fuse on the 3.3v line is also recommended; the
original schematics depict a 5amp fuse to prevent damage caused by accidental current spikes in the event the keyboard is accidentally unplugged.

|PS/2 Pin |Pi Pin | Function
|------- |----- |---------
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