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

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

CPU Load Maximum

Modules Module Tasks Public Functions and Data Author Main.c User Interface Task Current State Data Dean Zimmermann Timeslice Task Current Time/Date Data Struct Local Time/Date Data Struct Time.c Clock Task Time_DateGet(), Time_DateSet() Dean Zimmermann Weather.c SD-Card R/W Task Weather Data Structure Dean Zimmermann Sensor Task WeatherDataGet() Key.c Key Task KeyInit() Todd Morton GetKey() SPIDriver.c - InitSPI(), Read SPI(), WriteSPI() Dean Zimmermann LCD.c - LcdClrDisp(), LcdDispChar() Todd Morton LcdDispByte(), LcdDispString() LcdMoveCursor(), LcdCursor() OCDelay.c - OCDelay(), GetmsCnt() Todd Morton

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

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

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

Data Flow: User Interface-Display Weather.c Main.c Time.c Time/Date Time_DateGet() Data Structure Time_DateSet() Clock Task Weather Data User Interface Structure Task WeatherDataGet() Port E LCD Display

Data Flow: User Interface-Keypad Main.c Key.c Port B GetKey() User Interface Key Task Task

Questions?