PS2 keyboard

State of the part

This part is fully built and tested. We are currently working on integration testing.
Participators: Ferdinand, Johannes K., Julian D., Mona

Protocol

Schematics

Layout

Flash Program:

Main Pinout

INT		A0	A1	A2	A3		D0 (clk enable)	D1 (PS2_clk pull)	D2 (latch shift)	D3 (interrupt)		INT
0		0	0	0	0		0	0	0	0		0
1		1	0	0	0		1	0	0	0		1
2		0	1	0	0		1	0	0	0		1
3		1	1	0	0		1	0	0	0		1
4		0	0	1	0		1	0	0	0		1
5		1	0	1	0		1	0	0	0		1
6		0	1	1	0		1	0	0	0		1
7		1	1	1	0		1	0	0	0		1
8		0	0	0	1		1	0	0	0		1
9		1	0	0	1		0	0	0	0		0
10		0	1	0	1		0	1	1	0		6
11 (end of protocol)		1	1	0	1		0	1	0	1		10
12		0	0	1	1		0	0	0	0		0
13		1	0	1	1		0	0	0	0		0
14		0	1	1	1		0	0	0	0		0
15		1	1	1	1		0	0	0	0		0

Addressing

0x0008-0x000f on address bus
Equivalent to A4=1, A5-A16=0
So at address 16-31 D4 is high

Testing

We used an Arduino Mega in order to simulate address and data bus and resolve the received keycodes to chars.
The code can be found here.

Limitations

As of now, our design is not able to handle print screen, pause, arrows and other multicode keys.

Findings

• First proof of concept of our hardware interrupt setup successful
• Keyboard buffers data until our hardware is ready to receive
• Scan codes are very different for each standardized keyboard layout