LV1Ex

Embedded Software Final Exercise – Level 1 Page 1
Level 1: Count-Down Timer
0. Prerequisites
 Attended the training on Embedded Software
1. Input
 RL78/G14 RDK board
 CubeSuite+ E2.02.00I
 StarUML
 Workspace: Common Workspace  Final Exercise  L1 (empty)
 Requirements for this level (see Requirements below)
2. Output
 Sequence diagram (using StarUML)
 State transition diagram for switches (draw it before writing code)
 Source code
3. Task Description
You are going to write a program simulating the function of a count-down timer. You will be using the 3 switches on the board to set the time and start/pause/resume/reset the timer. The time is displayed on LCD device and your final program will show something like the following:
4. Requirements
Detailed requirements of this task are described as below.
4.1 LCD display
 The first line of the LCD display will show a message which is:
o “Setting…” when the system has just been reset or when the timer has just finished counting
o “Counting…” when the timer is counting down
o “Paused…” when the timer is in pausing state (see requirement 4.2)
 The second line of the LCD display will show the time in the format of XX:XX
o If the system has just been reset, this line will display 00:00
Embedded Software Final Exercise – Level 1 Page 2
4.2 Switches (SW)
 SW1 is used to set the second that varies from 0 to 59. When it is pressed, the second is incremented by 1.
 SW2 is used to set the minute that varies from 0 to 59. When it is pressed, the minute is incremented by 1.
 SW3 is used to:
o Start the timer to count down if the set time is not 0 (e.g. 00:00)
o Pause the timer if it is counting down
o Resume the timer if it is being paused
 While the timer is in pausing state:
o If SW2 is pressed, the timer will be reset (e.g. 00:00)
 Chattering has to be eliminated (review Chapter 7).
4.3 Time management
In this level 1, you are required to use “software way” to manage the time (review Chapter 6).
 Write a C function that manages the time.
 The above C function has an option which allows switching between using C code and assembly code to manage the time.
Recommendation: After having done this requirement 4.3, you should test both cases (C vs. assembly code) to compare their performance (which one is more accurate?).
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