1 / 19

System Software Design and Documentation

System Software Design and Documentation. Zach Hill Western Washington University. General System Design. MCU – Freescale MC9S12DP512 Bus Frequency of 16MHz Memory Requirements 12kB RAM 256kB Flash 4kB EEPROM MicroC/OS-II Tick period ~ 1mS. Tasks. Start Task User Interface Task

wvillegas
Télécharger la présentation

System Software Design and Documentation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. System Software Design and Documentation Zach Hill Western Washington University

  2. General System Design • MCU – Freescale MC9S12DP512 • Bus Frequency of 16MHz • Memory Requirements • 12kB RAM • 256kB Flash • 4kB EEPROM • MicroC/OS-II • Tick period ~ 1mS

  3. Tasks • Start Task • User Interface Task • Key Task • SPI Task

  4. ISRs • MP3_ISR • USB_ISR

  5. Task Design • Main: • Initializes I²C, SPI, MicroC/OS-II, and LCD • Creates Start Task • Start Task: • Displays Boot up message • Initializes USB, PWM, Key • Creates Other Tasks • Task Priority: 4 • Task Period – once

  6. Task Design • SPI Task • Waits for semaphore from MP3_ISR and USB_ISR • Sends or receives data over SPI depending on the semaphore posted • Priority: 5 • Execution Time: ?? • Period: ??

  7. Task Design • User Interface • Handles button presses from user • Task Priority: 6 • Execution Time: 4 mS • Task Period: 10 mS • CPU Load: .4

  8. Task Design • Key Task • Scans buttons, if one was pressed updates buffer • Priority: 7 • Task Period: 10 mS • Execution Time: 50 uS • CPU Load: .005

  9. MP3_ISR • Generates a semaphore when Data Request pin on the MP3 decoder goes high • Period: 1 mS (Sporadic) • Execution time ~ 291 nS (max)

  10. USB_ISR • Generates a semaphore when SPI ready pin on USBWiz OEM board goes high • Period: 1 mS (Sporadic) • Execution time ~ 291 nS (max)

  11. Overall CPU Load • CPU load L max= .4 + .005 + .000291 + .000291 = .405582 L max= 40.56% L average = 20.2%

  12. Kernel Selection • MicroC/OS-II • Real-time preemptive multitasking kernel

  13. Modules

  14. KeyFlag Dataflow Diagram Buttons Button Input Application Button Driver Module KeyInit() KeyPend() KeyTask() key KeyCodeTable

  15. Dataflow Diagram LCD Module LCD I/O Application UITask()

  16. USB_DATARDY MP3_RDY Dataflow Diagram SPI Module SPI I/O MP3 Data to decoder SPITask() MP3 Data From USB

  17. Dataflow Diagram Application IIC Module IIC I/O Decoder Control Commands UITask() IIC PWM Control Commands

  18. MP3_RDY Dataflow Diagram ISR SPI.c MP3_SPKR.c Interrupt SPITask Pend Post ISR MP3_Isr PORTH

  19. USB_DATARDY Dataflow Diagram ISR SPI.c MP3_SPKR.c Interrupt SPITask Pend Post ISR USB_Isr SCI

More Related