Embedded System Design

1
Embedded System Design

• Paul J. Weber
• October 12, 2006

2
Teaching at UMD

• ECE 1315
• Fall 2006
• Lab Instructor
• Spring 2006
• Lecture Lab Instructor
• ECE 2006
• Lecture Lab Instructor
• Senior Design Projects

3
Some ECE 2006 Basics

• Ohms Law
• v iR
• Kirchoffs Voltage Law
• ? v 0 (around a loop)
• Kirchoffs Current Law
• ? i 0 (at a node)
• Physics
• p iv
• i dq/dt

www.ece.uwaterloo.ca
4
Some ECE 2006 Basics

• Ohms Law
• v iR
• Kirchoffs Voltage Law
• ? v 0 (around a loop)
• Kirchoffs Current Law
• ? i 0 (at a node)
• Physics
• p iv
• i dq/dt

http//www.morphet.org.uk/images/ferro/ferro-log7s
ervice/circuit-150-16.gif
5
Projects atMichigan Tech
6
Electronic Design with Microprocessors

• CME11E9-EVBU
• Motorola 68HC11 Lab Development Kit
• LCD
• Keypad
• I/O
• Dragon
• 68HC12
• Programming
• Assembly
• Embedded C

1
2
3
A
B
4
6
5
I Love ECE!
7
8
C
9
D
0


7
I/O Options

• Polled I/O
• Are We There Yet?
• Busy Waiting
• Interrupts
• Flag When Ready
• CPU Free to Do Other Things
• Counters
• Flag When Rolling Over
• Time-stamping
• Precision

8
Stepper Motor Control (1 of 2)

• Hardware
• Parallel I/O
• 4 Control Signals
• Driver
• uC Current
• Software
• Stepping Sequence
• Gray Code
• 8 Step Sequence
• ISR Determines Timing
• Precision

9
Stepper Motor Control (2 of 2)

• Timer
• Interrupt Subroutines
• Goals
• Fixed RPM
• Bi-Directional
• Controlled Curve

10
Pulse Width Modulation

• DC Motor
• Analog
• Digital Control Device
• High/Low Voltage
• Variable Output
• Solution
• Pulse Width Modulation
• Duty Cycle

11
Steering Functionality (1 of 4)

• Variable Steering
• Greater Control
• Better Efficiency
• Different Speeds
• Different Functionality
• Three Ranges
• Normal
• Negative-Phase
• In-Phase

12
Steering Functionality (2 of 4)

• Normal Steering
• Front Wheels Always Turn
• Rear Wheels Straight
• Intermediate Speeds

13
Steering Functionality (3 of 4)

• Slower Speeds
• Negative-Phase Steering
• Rear Wheels Opposite
• Tighter Turning Radius

14
Steering Functionality (4 of 4)

• Faster Speeds
• In-Phase Steering
• Rear Wheels Follow
• Efficient Lane Changes

15
Mimicking Quadrasteer?

• Step 1 Wheel Speed
• DC Motor with Slotted Disk
• Pulse Accumulation
• Determines RPM
• Photo Emitter-Detector Pair

16
Mimicking Quadrasteer?

• Step 2 Drive Circuit Design
• 68HC11
• Low Power
• Drive Circuit
• Digital
• PWM

17
Mimicking Quadrasteer?

• Potentiometer
• Determines Steering Wheel Position
• Speed of Vehicle
• LCD Display
• Keypad Entry

Inc.
1
2
3
A
B
4
6
5
50 MPH
7
8
C
9
D
0

Dec.

Enter New
18
Steering Design Goals (1 of 2)

• Functionality
• Revolutions Per Minute
• Motor/Disc
• Hall Effect Sensor
• Pulse Accumulation
• Steering Wheel Position
• Potentiometer
• Look-Up Table (LUT)
• Current Vehicle Speed
• Front Wheel Position

19
Steering Design Goals (2 of 2)

• Functionality (Continued)
• Stepper Motor
• Front and Rear Wheels
• (Only One Pair for Project)
• Ensuring Safety
• Limited Turning Degree
• Boundary Cases
• Fail-Safe
• Default Mode

20
Cyclone II Programmable FPGA

• System On a Programmable Chip (SOPC) Generation
• NIOS II CPU
• Memory
• JTAG UART
• PIO
• Timers
• Etc.

www.clifford.at
www.altium.com
21
Thermostat

• Conversions
• Thermistor
• T?R
• Op-Amp
• R ? V
• ADC
• V?
• Hysteresis
• Heat Radiation

22
Classic Control Systems

• MATLAB Simulink
• Cart Position
• Cruise Control
• Proportional, Integral, Derivative (PID)
• System Response
• Settling Time
• Rise Time
• Overshoot

23
Real-Time System X-by-Wire Truck
14 42 V Alternators
36 Volt Battery Equivalent
Voltage Display
24
More Information

• 257 MWAH
• http//www.d.umn.edu/pjweber
• pjweber_at_d.umn.edu
• http//www.altera.com/
• http//www.pickuptruck.com/html/stories/qs420/page
  1.html