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Embedded Systems & Controls
Carving Out a Niche as a Mac SE Grad
Kevin Dagenais November 15 2007
Your Presenter
• McMaster SE 2003• McMaster MASc 2005
– Supervised by M.V.M– Theses: Alternate Fuel Injection Control
• ZENON Environmental/GE Water and Process
• Hy-Drive Technologies Ltd.– Embedded Systems Designer– Software Team Leader
State Machines and Medical Supplies
• We have a history– Intro to Professional Eng 2004-2005– I’m sorry if I tricked you into this!
• 3 Years later… Your Feedback… Please!
Relevant Projects
• Design of a Configurable Alternate Fuel Injection Controller
• Embedded Controls Development for A Hydrogen Generating System
• Design of gas flow regulation control system. (Just Underway)
• Telematics Integration, customized reporting.
A Green Alternative
• Natural Gas and Propane both burn cleaner than Petroleum.
• These fuels are usually more economical.
• Because they are Gaseous, injection pulses are longer.
• A viable solution for localized fleet operators (Taxi companies, Driving Schools).
Injection Control
• Fuel Injector Control
• Platform: PIC 18F452
• Hard Real Time Constraints
Injection ControlSystem Overview
Main Loop
• Evaluation of Safety and Diagnostic Conditions.
• Analogue Conversions
• State variable updates
ISR• Determine Cause of
Interrupt• Disable Interrupts and
clear flags• Handle event
– Change on Injection Signals (Ext I/O)
– Pulse Elongation complete (Timer Period Match)
– Unhandled Exception (Timer Overflow)
• Hydrogen Based Diesel Enrichment via Electrolysis.
• Improved Fuel Economy
• Reduced Exhaust Emissions
• Improved Horse Power
A Software Box(That makes Hydrogen)
• 2 Channel Safety with Monitoring• PID Pressure control• PWM Heater control• Telematics Integration • Co-operative Multitasking• OTAC• Periodic and Failure based reporting• Deployed Study performance• GPS Integtration
What is out of your control that Affects Timing?
• Characteristics of the related physical process• Hard Real Time Constraints • Frequency of Oscillation, Instruction Set, Pipeline Length• Available On Chip Peripherals
– Interrupt handler speed, available interrupts, max # of vectors– Timer speed, size, scaling, number, interaction
• Sensing response time, – TAQ, TAC, Sensing Mechanism
• External communication interfaces– Including on-board peripherals
• Total processor workload• The Rest is up to you!!.... (Is there anything left??)
The Stuff that’s Left
• System/State Design • Use of Interrupts• Extent of branching and conditionals in key
processes• Extent of context switching• Use of Assembly code• Task prioritization and scheduling• On-Chip peripheral configuration settings• Speed vs. Size• Task Offloading
Verifying Time Properties
• Design for Inspection, Inspect to Verify!• Limit the scope of inspection using
interrupts and appropriate priority assignment.
• Let the compiler documentation do the talking…
• Lose the printf’s, and all other debugging constructs.
• Scope it!
When Your Fastest Isn’t Fast EnoughSalvation Through Hardware
• Turn Analogues Inputs to Digitals
• Move Services off Chip to Dedicated Devices (Flexibility is about choice)
• Look for opportunities to trade size for speed.
I Never Thought…
Anyone would read my thesis.My Thesis includes complete code (PIC 18F452-C)
including:• Full Documentation• Examples of A/D conversion• Interrupt Handling• Serial Communication• Hard Real time control
It is available in the departmental office, and in the library.
Closing Thoughts
• Write the PPE Early, but not in Summer.
• Make good friends with your Hardware Guy/Gal.
• The Man Month isn’t mythical when you work on Salary.
• IntelliSense will only get you so far, and Nowhere in embedded.
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