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

Chapter 3 problems

      - B3.8 -

Designing an 8-bit comparator (μC - C)

Problems

B3.7

B3.9

1. Specifications

Design the 8-bit comparator represented in Fig. 1 using a PIC18F4520.

The same project is proposed in D1.8 as a combinational circuit based on logic gates.

Comparator 8 bit

Fig. 1. Comp_8bit symbol.

Some questions to organise the project:

- Use the pin connections represented in Fig. 1.

- List all the RAM variables involved in this design.

From a simiar tutorial in P9 or LAB9 where to copy and adapt to the project location folder:

- Draw an sketch of the hardware circuit and capture it in Proteus Comp_8bit.pdsprj

- Write the software source file Comp_8bit.c. Start an MPLABX - XC8 project targeted to the PIC18F4520 chip. Use our software organisation.

As we have decided, start compiling and testing one input or output at a time:

- Write the funcion init_system(). Start configuring only one input, compile and test. Describe using pictures and annotations how you are configuring registers.

- Write the funcion read_inputs(). Start reading only one input, compile and test. Describe using pictures and annotations how you are reading an input using bitwise C instructions.

- Write the funcion write_outputs(). Start writing only one output, compile and test. Describe using pictures and annotations how you are writing a RAM variable in the corresponding pin using bitwise C instructions.

- Translate the truth table to C code and complete truth_table().

- Check the full project and report.