turbine flow meter
DESCRIPTION
Turbine Flow Meter. Kevin Hooks Senior Design Project. Overview. Micro Controller Kernel, Tasks, CPU Load Data Flow Diagrams State Machine Diagrams Module, Public Tasks, Functions and Variables Questions?. Micro Controller. HC9S12DP512 16-bit device - PowerPoint PPT PresentationTRANSCRIPT
Turbine Flow Meter
Kevin HooksSenior Design Project
Overview
• Micro Controller• Kernel, Tasks, CPU Load• Data Flow Diagrams• State Machine Diagrams• Module, Public Tasks, Functions and Variables• Questions?
Micro Controller
• HC9S12DP512• 16-bit device • 512K bytes Flash EEPROM, 14K bytes RAM, 4K
bytes of EEPROM• 2 SCI , 3 SPI, 8-channel IC/OC ECT, two 8-
channel, 10-bit ADC, 8 channel PWM, 29 GPIO, 20 GPIO with interrupts
• 24 MHz Bus Frequency
Micro Controller
• About < 300 Kbytes Flash EEPROM• 1 SCI • 1 SPI• 2 IC/IOC (1 input capture, 1 Pulse
Accumulator)
Kernel
• Time Slicing• Period of 1s• Total Tasks 5• 1 Interrupts
Tasks
• LCD_Update• Pulse_Count• Period_Count• Thermo_Get• Calculate_Values
LCD_Update
• Checks for Display Units• Compares Current LCD Value with new LCD
Value• If different then update LCD display• Run Time ~10ms max, ~1ms Average• CPU Load ~ 10ms/1s = 10% max, ~1ms/1s =
1% average
Pulse_Count
• Counts Pulses for 10ms• Stores Value in public variable *Pulse_Val• Run Time ~10ms• CPU Load ~10ms/1s = 10%, should always be
10ms
Period_Count
• Counts the period of one pulse • Stores value in public Variable *Period_Val• Run Time Varies based on Frequency (Max of
1ms at frequency of 10kHz average of .5ms at 50kHz)
• CPU Load ~1ms/1s = 1% max, ~.5ms/1s = .5% average
Thermo_Get
• Performs an SPI read for one 16-bit value from the MAX6675 and stores into variable Thermo_Val. Only 12 bits are used so it will need to be masked.
• At 24MHz clock the runtime is max ~10uS• CPU Load = ~10us/1s =.001%
Calculate_Values
• Receives variables from each get task and performs a series of calculations to provide one final 8-bit result New_Value
• Checks for variable set by touch screen ISR to determine calculations for correct units
• Run Time ~10us• CPU Load = ~10us/1s = .001%
Get_Touch ISR
• If a screen touch is detected, jump to ISR• This ISR simply sets a variable to a specific
value. This will be used to determine unit display
• Run Time is ~1uS
Final CPU Load
• Max CPU Load = 10ms/1s + 10ms/1s + 1ms/1s + 1us/1s + 1us/1s = 21.002%
• Average CPU Load = 16.502%
Data Flow Diagram: LCD_Update Task
Data Flow Diagram: Pulse_Count
Data Flow Diagram: Period_Count
Data Flow Diagram: Thermo_Get
Data Flow Diagram: Calculate_Values
Data Flow Diagram: SCI_Read_Isr
State Diagram for UI
Initial State
Modules, Tasks, Public DataModules Tasks Public Functions and Data
Main.c WaitForSlice(),
LCD.cModified from Trevor Wilcox
LCD_Update() Prev_ValDisp_Val()Get_Touch()Compare_Val()SCI_read_Isr()
Calculation.c Calculate_values() New_ValUnit_Val
OCDelay.cTodd MortonSPI.c Thermo_Get() Thermo_Val
ECT.c Pulse_Count(), Period_Count()
Pulse_Val, Period_Val
9S12DP256Start.cTodd Morton
Questions?