North Sales Meeting

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Using a Web 2.0 Approach for Embedded
Microcontroller Systems  J. O. Hamblen and G.
M. E. Van BekkumSchool of Electrical and
Computer Engineering, Georgia Institute of
Technology, Atlanta, Georgia, USA
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Microcontroller-based Embedded Systems Courses

• Similar undergraduate courses can be found at
  many schools (including EE, CmpE, and CS)
• Most new design activity is now focused on 32-bit
  devices
• C/C remains the most widely used language in
  industry
• Networking support is often needed Internet of
  Things
• Many hard adoption choices to make initially
• Textbooks
• Microcontroller
• Tool chain
• Development board
• Sensors and I/O Devices
• Software Support Infrastructure (Drivers and Code
  Examples)

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ARMs mbed Rapid Prototyping Platform

• Hardware Software, using a Web 2.0 Solution

C/C Cloud Compiler
Website with code examples
DIP Prototyping Form-Factor
High-level Peripheral APIs
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ARM mbed microcontroller module

• ARM 32-bit Cortex-M3 MCU in a Prototyping
  Form-Factor
• 0.1 pitch 40-pin DIP module with USB Flash
  Drive interface to PC
• Nothing to install or configure, practical for
  breadboard and PCBs
• Powered from USB cable, battery, or external
  power supply
• Module cost is about half the price of a current
  college textbook
• Free accounts for students in a class via email

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Microcontroller Hardware Features

• NXP1768 32-bit ARM Cortex-M3 SOC running at
  96MHz
• 512KB FLASH and 64KB RAM on-chip
• Ethernet, USB, CAN, SPI, I2C, Serial, PWM, ADC,
  and DAC I/O
• interfaces are all on-chip

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Easy to extend it to store lots of data

• A final system might want to store lots of data
• Hardware for an SD Card is minimal
• SPI Port connection using simple breakout
• Only 4 wires power needed
• File system code provided
• Can also use a USB flash drive

GND MISO p6 SCL - p7 Vcc MOSI p5 nCS - p8
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Baseboard or Breadboard?

• A baseboard contains the common I/O connectors
  and a small prototyping area, so for basic labs
  there is nothing to wire up.
• A breadboard will require wiring some
  connections, but is more flexible for custom
  hardware designs and design projects. Most
  external I/O devices are serial (i.e., Ethernet,
  USB, SPI, I2C, RS232) and will only need a few
  jumper wires.

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Breakout Boards for Student Breadboards

• Breakout Boards make it easy for students to use
  modern surface mount devices on a breadboard
• Low-cost, preassembled, and commercially
  available
• Wide selection of devices for the new large
  hobbyist market

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Popular Breakout Boards for Student Projects
Purpose Sensor or Device Interface, IC, and comments
Display ASCII text BW Text LCD Display Parallel Digital - HD44780
Display text and graphics Color LCD graphics display SPI Nokia 6100 128x128
VGA display on a monitor VGA controller TTL Serial PICASO-SGC
Add digital audio output MP3/AAC/WMA decoder SPI - VLSI VS1033
Touch switch or keypad Touchpad controller I2C Freescale MPR121
Measure motion or orientation MEMS Gyro Accelerometer I2C ITG322 ADXL345
Measure environmental data Temperature Humidity Serial - Sensirion SHT15
Location and speed GPS receiver RS232 Serial NEMA - various
Direction Electronic Compass I2C - Honeywell HMC6352
Measure Distance IR reflection Analog or Digital - Sharp GP2xx
Ultrasonic Range Sonar (longer range than IR) Analog or Serial - MaxSonar XL EZx
Cell phone network for data Cell Phone modem module RS232 Serial, need SIM - various
Wireless data transmission Zigbee/XBee Serial Digi XBee XBPxx
Displays 230 colors on LED RGB LED driver SPI - Allegro A6281 on ShiftBrite
Use PWM to drive DC motors H-bridge driver PWM STMicro VNH3SP30
Add networking MagJack connector Ethernet
Connect to a serial port RS232 level convertor RS232 Serial - various
Add USB thumb drive USB A connector USB various
Add flash file system Micro SD card connector SPI various
Add mouse and/or keyboard PS/2 connector PS/2 serial protocol
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Web 2.0 Tools

• Dedicated Developer Web Platform
• Custom Web 2.0 tools and Cloud Compiler
• User Forum, API Documentation in Handbook
• Wiki Code Examples in Cookbook

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Cloud Compiler

• Cloud-Based C/C Compiler
• Web 2.0 browser-based IDE with personal file
  space in the cloud
• Nothing to install or configure, login from
  anywhere
• Based on the Keil Tools C/C compiler widely
  used in industry
• Javascript (AJAX) based environment for compiling
  code
• Only two mouse clicks to compile and download
  flash to run code

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mbed I/O API Library

• High-level I/O Peripheral APIs
• Trades a bit of memory and CPU performance for
  ease of use
• Abstract software interfaces for controlling
  microcontroller hardware
• Intuitive peripheral access, encapsulation of
  implementation details
• Treat hardware and software the same
• Online Handbook with documentation code
  examples for all APIs

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Cookbook Wiki

• User contributed code examples and hardware
  designs
• Easy to import libraries and projects via web
• Support for networking, displays, and many
  different
• types of sensors and I/O devices

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Debug Support

• No hardware breakpoints!
• Would be nice, but can live without it given the
  other advantages
• Not as big a drawback as we expected
• Can also emulate small code segments using free
  Keil Tools offline
• Four onboard easy to use user LEDs
• LEDs will also flash on a run time error
• printf() prints over USB to any PC Terminal
  Emulator Program
• module works like a USB Virtual COM Port

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Student Design Projects

• Teams of two students with two weeks for mini
  design project
• Design project comes after two introductory labs

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Internet of Things Student Projects

• An internet enabled clock that syncs to a time
  server
• Text LCD and network magjack breakout boards
• Based on LCD and network drivers from the Cookbook

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Internet of Things Student Projects

• An internet radio receiver
• MP3 decoder chip, audio jack, network jack, and
  USB flash driver breakout boards
• MP3 and network drivers adapted from Cookbook
  examples

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Internet of Things Student Projects

• Universal Translator
• MP3 decoder chip, Text LCD, audio jack, network
  jack, PS/2 jack, and Micro SD Card breakout
  boards
• Uses Googles Internet APIs for translation and
  speech

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Graphics and Games

• Classic Pong Game
• Nokia Cell Phone 130 by 130 Color LCD breakout
  board
• Small low-cost VGA breakout boards are also
  available
• Graphics driver used from Cookbook

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Control Systems

• A self-balancing two wheel robot using two
  low-cost geared DC motors with a built-in
  quadrature encoder feedback
• H-bridge MOSFET driver, MEMs Gyro and
  Accelerometer breakout boards
• Uses PWM for motor control, MEMs IMU, and a PID
  control loop - all from Cookbook code examples

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Assessment Data

• 1-strongly disagree 3-Neutral 5-strongly
  agree
• I think the experience with labs that used
  breadboards with breakout boards was worthwhile.
  - 4.4
• I would prefer labs where everything was already
  connected on a circuit board even though I might
  have somewhat less flexibility to do different
  things on projects. - 1.87
• I would prefer an mbed design project rather than
  a third traditional lab assignment for mbed.
  4.0
• I would prefer the cloud compiler web browser
  approach versus a more traditional development
  tool that was only available for use on the
  laboratory PCs. (Assuming they have the same
  features) - 3.6
• I would prefer electronic copies of course
  materials versus traditional printed course
  materials and printed textbooks. (Assuming
  content and cost are about the same) - 3.8
• I prefer a team design project with presentations
  over a more traditional final exam. - 4.86

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Conclusions

• There is some value in returning to a Student
  Breadboard approach for embedded systems labs
• The cloud compiler approach works well for
  student labs and greatly reduces the computer
  support issues
• Higher-level I/O support APIs work well for the
  new generation of microcontrollers and save
  development time
• Networking is needed in these courses and leads
  to more interesting Internet of Things design
  project options
• For such a course, having the all of the
  resources online may be a better option than
  printed textbooks and lab manuals. Students now
  appear to prefer online electronic copies.

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References

• 1 M. Barr, Real men program in C, Embedded
  Systems Design, 2009 Online. Available
  http//www.embedded-systems.com/design/218600142
  
• 2 ECE 4180 Embedded Systems Design Online
  Available http//www.ece.gatech.edu/hamblen/4180
  
• 3 Ashlee Vance, You Too Can Join the Internet
  Of Things, New York Times, September 20, 2010.
  Available http//bits.blogs.nytimes.com/2010/09/2
  0/you-too-can-join-the-internet-of-things/
• 4 S. Ford, Rapid Prototyping for
  Microcontrollers,Online. Available
  http//mbed.org/media/press/mbed_whitepaper.pdf  
• 5 ARM University Program Online. Available
  http//www.arm.com/support/university/
• 6 J. Hamblen, IC Sensor and Driver Breakout
  Boards Online. Available http//mbed.org/cook
  book/IC-Sensor-and-Driver-Breakout-Boards
• 7 Mbed Cookbook Wiki Online. Available
  http//mbed.org/cookbook/Homepage
• 8 Mbed Educational Program Online. Available
  http//mbed.org/handbook/Education
• 9 Mbed Handbook Online. Available
  http//mbed.org/handbook/Homepage
• 10 Mbed Forum Online. Available
  http//mbed.org/forum/
• 11 J. Hamblen, Mbed Student Projects, 2011
  Online. Available http//mbed.org/cookbook/Stud
  ent-Projects