Transcript Embedded Computer Systems Elec471

Embedded Computer Systems
Elec471
Welcome remarks and Class Overview
Associate Professor
Cap’n Tim Johnson, PE
Welcoming Remarks
• In your previous class, Elec 244 Digital
Systems, we learned about digital logic and
the building blocks for memory.
• You were introduced to a microcontroller and
ran small computer programs to control LEDs.
• In this class we will learn about systems which
control real processes and build basic designs.
• At the process’s core is a microprocessor
running a program.
Welcoming Remarks
• In this course we learn about and use analog to
digital conversion (ADC) hardware and how to
control the operation of a system.
• All these designs run C code so we’re going to
become better at all aspects of coding by
practice.
• No systems is of any use unless it’s serving a
distinct purpose.
• We’re going to learn how to use mathematics to
model the process and determine how well we
serve that purpose.
Welcoming Remarks Conclusion
• Everything you learn in this class is directly useful
in your junior and senior design classes.
• All you have to do is:
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Come to class
Pay attention and take notes
Do the homework
Do the labs
Take some tests
Think about what you’re learning and how it’s used.
Why would I say…
• …think about what you’re doing and how it’s
used?
• The answer is: Time and Materials
• We only have 1 semester for this course.
• We only have a few practical systems.
• So it’s the process that’s the same and you just
substitute out different parts. The parts are the
peripherals (I/O in & out), the processor, the
memory, and the interfaces. I/O in are sensors.
The I/O’s out can be a communication bus,
display devices, or memory.
What process?
• A real-time process takes constant reading of
its environment, let’s assume its a beaker of
water that needs to be boiling. We need
several things to have this happen:
• A beaker
Process description:
the water enters a container, turn
• Water
on the heat, wait until the water
• Heat
boils, turn the heat off, and move
the water to its intend use.
• Time source
Let’s automate the process
• Verify the beaker is in position using a simple
switch or a break in an optical signal.
• Apply voltage to the motor driving the valve to
open. A limit switch in the valve opens the
voltage to the motor turning the motor off.
• A float switch or other device detects the
necessary water level and signals the motor to
reverse the polarity causing the motor to close
the valve.
• A different limit switch in the valve opens the
voltage to the motor turning the motor off.
Automated Process part II
• The heating source is next turned on. Depending on
the type of heating source there are different ways of
turning the heat on and off.
• Is the water is boiling yet? There are several methods
of determining this information. A thermocouple will
give a temperature readout that varies directly with
the temperature. This information has to be converted
to digital data to be read.
• Whatever is used has to turn the heat off when the
boiling point is reached and signal that the process is
complete.
Function Block Diagram
• The heating element generates heat due to the current
flowing from the AC source thru the relay (closed thru
when the I/O output voltage is ON).
• The thermocouple absorbing the heat causing a smaller
measureable current to flow in its output wiring.
• The ADC converts the current to a voltage then converts
the voltage to a digital output.
• The code evaluates the digital output for the temperature
setting the I/O register ON or OFF controlling the relay.
Sample Process
In the above process the multi-meter converts the current flow from a thermocouple
connected to a soldering iron to an analogue voltage reading and off to the side is a
computer running LabView that turns the power supply on and off.
Transition Slide
• This course this year will be different from
“normal”.
• I’m hoping to have most of the lectures posted on
blackboard.
• Grading will be done on blackboard.
• You’re only going to learn as much as you are
interested in.
• My job is to evaluate your learning.
• The syllabus is posted on my website:
www.myweb.wit.edu/johnsont
Weekly expectations
• You have viewed whatever power point has
been posted.
• You have “tested” yourself.
• You have completed a lab or portion of a lab
associated with the lecture.
• You have added vocabulary to a list of new
words you have learned or plan to learn.
• You are capable of discussion and/or have
questions related to this or previous learning.
Weekly Journal
• You have added your ideas/discussion/ questions
to your journal.
• You have written up the weekly lab. Hand in a
copy to me of your journal entry.
– What you did.
– What your results were.
– What you thought of the lab.
• State whether or not the lab exemplify the lecture or a
specific lab learning objective?
• Whether you had trouble in the lab and what you did to
attempt a solution.
• What your solution was.
Lab Report
• Should have a cover page
• Should include all names of person present
during the lab that participated in doing the lab.
• Should have the section that the lab is for.
• Should contain original writing amount to
approximately 100 words or more.
• Copy Word Count into your lab to verify.
• Screen shot of your work if done on a computer.
• Explanations of what you did as mentioned on
previous slide.
FAQ
Q#1 What do I really want?
• Oh, I forgot to mention you really have to get
down with software. I’m firmly convinced the
future of hardware is software. So, a software
guru called Bucky Roberts is going to teach you
everything you wanted to know. He has 15
videos on C programming. Know them. When
the class is ready, I’ll test you on your knowledge.
His lessons are located here:
http://thenewboston.org/tutorials.php
• We’ll have more lessons as the semester goes on.
FAQ
Q#2 What do we doing this week?
• We’re going to start learning LabView.
• Immediately following the Q&A session for
this power point.
• There will be instructions in the power point
regarding homework for LabView.
• The lab will be Interfacing LabVIEW with Test
Bench Instruments found on my website.
Assignment #01A
• Draw a FBD (function block diagram) for a simple
bottle opener that provides an audible message
upon activation.
• Here’s a link to a representative design:
http://www.youtube.com/watch?v=_qFFkO6NcKE
• Here’s a link to MSP430 microcontrollers:
http://www.ti.com/lit/sg/slab034u/slab034u.pdf
• Here’s a link to a somewhat useful DAC tutorial:
http://www.eetimes.com/electrical-engineers/educationtraining/tech-papers/4207829/A-DAC-Applications-Tutorial