1. System Software Design by Chan-Chia (James) Chang
LED Display Panel
System Software Design
by Chan-Chia (James) Chang

2. General System Design MCU Motorola 9S12DP256B 24 MHz Bus Frequency
256K Byte Flash
12K Byte RAM
4K Byte EEPROM

3. Kernel Selection
MicroC/OS-II
Real-Time Preemptive Kernel

4. Priority of Tasks 4 – Start Task 5 – Clock Task 6 – TrafficLight Task
7 – LED Task
8 – KeyPress Task

5. Start Task Initialize the system Priority #4 Period: run it only once
Execution time: 2ms

6. Clock Task Counts every second Priority #5 Period: 1sec, periodic
Execution time: 1us

7. TrafficLight Task Control traffic lights Priority #6
Period: 0.5sec, periodic
Execution time: 1us

8. LED Task Controls LEDs flash, and input data into LED drivers
Priority #7
Period: 10ms, periodic
Execution time: 48us

9. KeyPress Task Determent if someone pushes the buttons Priority #8
Period: 10ms, periodic
Execution time: 2us

10. CPU Load Lmax = 1us + 1us + 48us + 2us 1s 0.5s 10ms 10ms Lmax = 0.5%
Lavg = 0.26%

11. Modules Task Public Functions and Data Main.c Start Task Traffic.c
TrafficLight Task
Traffic()
PICDisp.c
LED Task
PICDisp()
LEDWrite.c
LEDWrite()
KeyPress.c
KeyPress Task
KeyInit(), KeyPend()
Clock.c
Clock Task
Time()

12. Data Flow Diagram User Application Display Store Picture Display
KeyPress.c
LEDWrite.c
PICDisp.c
LED Display
Display
Traffic.c
Traffic LEDs