The PS2 port was developed by IBM for interface keyboards and pointing devices. It uses synchronous serial signals to communicate between the keyboard and mouse to the computer. All the signals are TTL logic level voltages i.e., 0 volts for logical 0 and +5 volts for logical 1. It also supports bi-directional communications.
When a PS2 mouse sends its information it must send 3 consecutive data packets in a row. Each packet sent has different information i.e., for button pressed, movement and direction of movement.
PS/2
|
Pin |
SIGNAL NAME |
|
1 |
Data |
|
2 |
Reserved |
|
3 |
Ground |
|
4 |
+ 5 Volts |
|
5 |
Clock |
|
6 |
Reserved |
Data: Mouse data packets / Keyboard scan codes are sent serially from the mouse or keyboard to the computer on this single wire.
Clock: This signal is sent from the mouse or keyboard to synchronize the data signal.
Ground: This is a common ground signal used as a return path for data and is a reference to logical 0.
