UPC EETAC Bachelor's Degree in Telecommunications Systems and in Network Engineering EEL

Chapter 2 problems

     - D2.15 -

Registered 16-key matrix encoder with handshake




1. Specifications

The idea is to add communication signals to the basic Matrix_encoder_16key to be able to connect this keyboard controller (slave peripheral) to a master device or a microcontroller, like data available (DA) and data acknowledged (D_Ack) in Fig 1. Note that the CLK frequency for scanning keys (MCLK) may be very different to the system CLK (SCLK) running in the computer.


Fig 1. Symbol for the proposed top entity  Matrix_encoder_16key_registered with handshake capabilities for buffering and synchronising the matrix encoder to the system CLK (SCLK).


In Fig. 2 we have inferred a circuit to be able to register the code of the key pressed until the computer can read it, thus establishing a kind of handshaking between computer and peripheral (the matrix keyboard) using signals like data available and data acknowledged.

Fig 2. Proposed architecture including project Matrix_encoder_16key as Chip1.


Some hints for starting this project at this discussion: state diagram and example of timing diagram.