Using LEDs, LCDs and GLCDs in Microcontroller Projects

15.1 PROJECT 15.1 – Countdown Timer

15.1.1 Project Description

This project describes the design of a countdown timer using the MikroMMB board for PIC18FJ (from now onwards, this board will be called the MikroMMB board). The screen consists of a soft keypad with numbers 0 to 9, a START button, a CLR button and a display box. The operation of the project is as follows: the user enters a starting number and clicks the START button. The display counts down in 1 second intervals until the count reaches zero and then it stops. Clicking the CLR button clears the display and the system is ready for the next count.

15.1.2 Block Diagram

The block diagram of the MikroMMB board is shown in Figure 15.1. A detailed circuit diagram can be obtained from the manufacturer's product guide.

Figure 15.1 Block diagram of the MikroMMB board

The steps for creating this project are given below:

1. Create Project File

Start the Visual TFT software. Select Project -> New from the top-down menu. Enter the project name and choose the desired project path. Then click OK. The name STOPWATCH is given to the project.

2. Configure Project

In the Project Settings window, make the following settings:

15.1.2.1 General (see Figure 15.2)

• Hardware patterns: MikroMMB_for_PIC18FJ_hw_rev_1.05;
• Target Compiler: mikroC Pro for PIC PRO for PIC;
• Target Device: PIC18F87J50;
• Device Clock (Hz): 48 000 000.

Figure 15.2 ...