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Bicycle Information Tracking System. System Software Design Review. BITS General System Software Design. MCU: NXP LPC2378 ARM7 32-bit 512 KB Flash, 8KB EEPROM and SRAM Bus Frequency: 20 MHz Approximate Memory requirements: ROM: ~220 KB maximum
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Bicycle Information Tracking System System Software Design Review
BITS General System Software Design • MCU: NXP LPC2378 ARM7 32-bit • 512 KB Flash, 8KB EEPROM and SRAM • Bus Frequency: 20 MHz • Approximate Memory requirements: • ROM: ~220 KB maximum • Includes FatFS file system, drivers for all peripherals • RAM: ~2 KB • SD Card: 1 KB on a FAT formatted 256 MB card • Resources used: • 5 GPIO, 1 SPI, Micro-SD card
BITS System Software Design: Kernel • Timeslice based system • Shared resources use flags • FatFS file system • Open-source system for SD card read/write • Tick period: 1 ms • Number of tasks: 4 • AppInit, Input Task, SDCard, UI Display
BITS System Software Design: Tasks • Start Task • Initializes all resources including LCD, SD card, and GPIO, checks SD card for previous data. Displays splash screen • Only runs at beginning • Execution time: 3 seconds • Input task • Monitors GPIO port P3 for input from Hall Effect Sensor • Uses this information to perform calculations • Monitors GPIO port P4 for input from switches, as well as information from the touchscreen • Toggles turn signals, changes data shown on screen • Monitors input from Touch Screen • Period: 1 ms • Execution time: ~10 us
BITS System Software Design: Tasks • SDCard task • Writes strings and data to SD card when prompted by the user • Period: ~20 ms (Sporadic) • Execution time: ~3 ms • UI Display task • Controls displayed information on the screen based on Touchscreen/GPIO input, also calculates information obtained from P3 to determine distance and speed. • Period: ~10 ms • Execution time: ~1 ms
BITS System Software Design: Tasks Maximum CPU load: 26% Average CPU load: 8%