SOLAR POWERED FIELD WEATHER STATION System Software Design Dean - - PowerPoint PPT Presentation

SOLAR POWERED FIELD WEATHER STATION

System Software Design Dean Zimmermann

WWU Spring 2010

General System Design

 Freescale 9S08QE128 Microcontroller  24 MHz Bus Frequency  Available Memory:

128K Flash/8K RAM

 Required Memory:

10K Flash/4K RAM

 Timeslice Kernel – 10ms Period

• Timeslice Task
• User Interface Task
• Clock Task
• Sensor Task
• SD-Card Write/Read Task
• Key Task

Timeslice Kernel Tasks

Timeslice Task

 Period: 10ms  Waits for periodic timing event to initialize task

loop

 Puts the MCU to sleep to save power

User Interface Task

 Period: 50ms (periodic)  Execution Time ~ 2ms (max)  Displays information on the LCD and controls LEDs  Handles user inputs to:

 Change State  Set Time and Date  Set Sample Rate  Navigate Stored Data

Clock Task

 Period: 1s (periodic)  Execution Time ~ 4us (max)  Updates Time and Date information

Sensor Task

 Period: 500ms (periodic)  Execution Time ~ 3ms (max)  Receives information on A/D convertor  Reads timer channel  Communicates with pressure module through SPI  Performs necessary calculations and uses lookup

tables to convert data into meaningful forms

SD-Card Write/Read Task

 Period: Sample Rate (sporadic)  Execution Time ~ 1 ms (max)  Uses SPI to communicate with SD-Card module  Writes data to SD-Card

 Writes at the sample rate specified by user  Stores data blocks with time and date stamp

 Reads Data blocks to display on LCD

Key Task

 Period: 10ms (periodic)  Execution Time ~ 2 us (max)  Checks for key presses  Updates key buffer

Maximum

CPU Load

Modules

Module Tasks Public Functions and Data Author Main.c User Interface Task Timeslice Task Current State Data Current Time/Date Data Struct Local Time/Date Data Struct Dean Zimmermann Time.c Clock Task Time_DateGet(), Time_DateSet() Dean Zimmermann Weather.c SD-Card R/W Task Sensor Task Weather Data Structure WeatherDataGet() Dean Zimmermann Key.c Key Task KeyInit() GetKey() Todd Morton SPIDriver.c

• InitSPI(), Read SPI(), WriteSPI()

Dean Zimmermann LCD.c

• LcdClrDisp(), LcdDispChar()

LcdDispByte(), LcdDispString() LcdMoveCursor(), LcdCursor() Todd Morton OCDelay.c

• OCDelay(), GetmsCnt()

Todd Morton

Overall State Diagram

REC REC LIVE/PAST LIVE/PAST SET SET’ SET (3 sec.) SET Past Live (reset) Button Hold Set Record

Data Flow: Sensors

Weather.c ADC I/O SPIDriver.c SpiRead() Timer 3 Channel 0 PTF0 PTF1 Weather Data Structure Sensor Task

Data Flow: SD-Card

Weather.c Main.c SPIDriver.c SpiRead() Weather Data Structure SD-Card R/W Task SpiWrite() Time/Date Data Structure

Time_DateGet()

Data Flow: User Interface-Display

Main.c Weather.c Time.c Port E Time/Date Data Structure User Interface Task Clock Task Weather Data Structure

Time_DateGet() Time_DateSet()

LCD Display

WeatherDataGet()

Data Flow: User Interface-Keypad

Main.c Key.c User Interface Task Port B Key Task

GetKey()

Questions?