1. Wireless Optical USB Mouse
System Software Design
By: Reza Afshari
April 26, 2005

2. Kernel Selection Micro C/OS-II
Real-time Preemptive Multitasking Kernel
Task Synchronization

3. Task Priorities Startup Task – 4 Power Management Task – 5
Sensor Task – 6
Button Detection Task – 7
Encode Task - 8

4. Startup Task Priority: #4 Description Initializes System Creates Tasks
Period: One time through (at startup)
Execution Time: ~50us

5. Power Management Task Priority: #5 Description Period: ~1 ms
Places mouse in lower levels of power consumption during times of no movement
Period: ~1 ms
Execution Time: ~15 us

6. Sensor Task Priority: #6 Description Period: sporadic
Receives optical sensor movement, if any, and updates the buffer.
Period: sporadic
Execution Time: ~5 us

7. Button Detection Task Priority: #7 Description Period: Sporadic
Checks the status of the two mouse buttons and updates the buffer.
Period: Sporadic
Execution Time: ~5 us

8. Encode Task Priority: #8 Description Period: sporadic
Converts the movement data and button status into mouse report format using the microsoft mouse protocol
Period: sporadic
Execution Time: ~20 us

9. CPU Load L max = 15 us + 5 us + 5 us + 20 us 1 ms 1 ms 1 ms 1 ms
= 4.5%

10. Module Description Reused Code: SPI_DRIVER.c, written by Jon Peterson
Mouse.c
SPI_DRIVER.C
Power.c
Input.c
Encode.c
Tasks
Main()
Startup()
PowerManage()
Sensor()
Button()
Encode()
Functions/Data
InitSPI()
WriteSPI()
ReadSPI()
PowerState
Left button status
Right button status
Movement data
Reused Code: SPI_DRIVER.c, written by Jon Peterson

11. Power Management State Machine

12. Data Flow Diagram – Button Detection Task

13. Data Flow Diagram – Sensor Task