Wireless Optical USB Mouse

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

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

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 • 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 • Receives optical sensor movement, if any, and updates the buffer. Period: sporadic Execution Time: ~5 us

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

8. Encode Task • Priority: #8 • Description • 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

11. Power Management State Machine

12. Data Flow Diagram – Button Detection Task

13. Data Flow Diagram – Sensor Task