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System Software Design. Doorbell Jukebox Henry Arbicor and Arthur Bingcang. General System Design. MCU – Freescale MCF52233 Bus Frequency – 60 MHz Memory Requirements 12 kB RAM 37 kB FLASH, no paging Timeslice Kernel Timeslice period: 10ms. Tasks. Start Task MP3 Task Push-button Task
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System Software Design Doorbell Jukebox Henry Arbicor and Arthur Bingcang
General System Design • MCU – Freescale MCF52233 • Bus Frequency – 60 MHz • Memory Requirements • 12 kB RAM • 37 kB FLASH, no paging • Timeslice Kernel • Timeslice period: 10ms
Tasks • Start Task • MP3 Task • Push-button Task • LCD Task • Play Task
Start Task • Initializes the system • Sets up the order in which the other tasks will run • Period: Once at Start-up • Execution Time: 100ms
MP3 Task • Reads MP3’s from MMC card and displays song names on the LCD • Sets pointer that will move when different songs are selected • Period: 100ms (periodic) • Execution Time: 5ms
Push-button Task • Recognizes push-button press • De-bouncing • Sets state • Up • Down • Select • Sequential • Doorbell • Period: 10 ms (sporadic) • Execution Time: 5 us
LCD Task • Display’s song names • Adjusts display according to current state • Period: 100ms (periodic) • Execution Time: 2.5ms
Play Task • When in Doorbell state, decodes and plays the selected song • Period: 10ms (periodic) • Execution Time: 3ms
CPU Load • Load (max) = 5ms/100ms + 5 us/10ms + 2.5ms/100ms + 3ms/10ms = .3755 = 37.55% • Load (average) = 5ms/100ms + 2.5ms/100ms = .075 = 7.5%
Dataflow Diagrams: LCD Jukebox.c LCD I/O Push-button Task Button LCD Task LCD MP3 Task
Dataflow Diagrams: Audio Out Jukebox.c External Hardware MMC Card MP3 Task Speaker DAC Push-button Clock Play Task