Appendix 3: Schematics
Figure 1
The following diagram illustrates the generic transmission:
source: http://www.beyondlogic.org/keyboard/keybrd.htm
Figure 2
The following diagram shows the output pins of the keyboard, and how we connected them to the keyboard MCU:
source: http://www.beyondlogic.org/keyboard/keybrd.htm
Figure 3
The following figure shows the circuit for video output generation:
Figure 4
The following is the state diagram for decoding the keyboard:
Figure 5
The following is the diagram of the master/slave configuration for the SPI:
Source: Atmel Mega32 Specification