Practical Embedded Controllers: Troubleshooting and Design

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Practical Embedded Controllers:

Troubleshooting & Design


Embedded Controllers

• Used in Most Commercial and Industrial Electronic Equipment

• Intelligent Electronic Devices

• Used to Control and Monitor Devices Connected to the Real World

• The Heart of PLC, DCS and Fieldbus Control Systems


Microcontroller Design and Functions• Central Processor Unit (CPU)

Is the Brain .

• The Program Resides in RAM, EEPROM or EPROM.

• The Microcontroller Can Store Data.

• Communicates to the Outside World.


Programming

• The Program Is a Sequence of Instructions That Tell the CPU What to Do.

• The Instructions Sent to the CPU Are Very, Very Simple.

• Upper Level Programming Languages Like Basic and C++are Often Used.


Main Components of the Microcontroller

• CPU

• External Address Bus

• External Data Bus

• External Control Bus

• Internal RAM

• Internal ROM

• Internal EPROM

• Internal EEPROM

• Internal Registers

• Digital Inputs

• Counter Inputs

• Digital Outputs

• Analog Inputs

• Serial Data Communications

• Parallel Ports


Block Diagram of the HC11


Microcontrollers• CPU Uses an Internal Parallel Address and Data

Bus to Communicate With Memory Components Like RAM, EEPROM and ROM.

• Internal Bus to Talk to Communication Systems, I / O Ports and Registers.

• RAM, ROM, EPROM and EEPROMs Are Used to Store (Either Temporary or Permanently) Data and Program Instructions.


Microcontroller

• The Parallel Ports Such As A, B, C, D and E Can Be Used to Transfer Data to and From External Memory Chips or Devices.

• These Ports Can Be Used to Read and Write to Devices Like Keyboards and LCDs.

• An External Parallel Data Bus Can Also Be Used by the Microcontroller to Activate or Read External Devices Like Switches, Relays, and LEDs.


Assembly Language Programming

• In Its Simplest Form, a Program Is a Sequential Set or List of Instructions That Tell the Microcontroller What to Do.

• A Subroutine Is a Small Part of the Overall Program..


Start the CarPut Key in Ignition

Started Turn Key Clockwise to the Start PositionHas the Car Started?Car Has Started, Release the Key, Go to “End”If Not, Continue to Hold the KeyLoop to “Started”

End Return to Main Program ( i.e. Drive the Car )

Jump to “Start the Car” Subroutine


Flow Chart to Start the Car

P ut Key inIgnition

T urn Cloc kw is e

D rive the Car

S tar t the Car

H a s T h e C a rSt a r t e d ?

N o

Yes


Memory Map

• A List of Address Locations in the Microcontroller System Where the Program, Ports and Various Other Devices Reside• Address Locations of RAM, ROM, EPROM and

EEPROM • Address Locations of “Vectored” Jump

Locations• Address Location of Input, Output and

Communications Locations


Vectors

• A Vector Is the Location of the Beginning of a Subroutine or Function of the Program.

• A Vector Could Be a Memory Location, Where a Jump Is Located.


Inputs and Outputs

• Digital Inputs and Outputs on the Microcontroller Are Located Within the Ports A, B, C, D, or E


Inputs and Outputs• Some of These Ports Are Defined As Fixed Inputs or Outputs While Others

Are Bi-directional.

• Ports That Can Be Setup Within the Program As Inputs or Outputs Are Called Bi-directional I/O.

• A Single Bit Changed From a 0 to a 1 in a Particular Register Can Determine Whether a Line on a Port in an Input or an Output.

• The Definable I/O Is Accessed by Setting up a Register Located at Certain Addresses in the Memory Map.

• Registers Are Usually 8 Bit Devices Where Each Bit Has a Special Function.

• Analog Inputs Are Sometimes Included on the Microcontroller, but Most of the Time They Are a Function of External Chips Connected to the Microcontroller


Inputs and Outputs

• The Definable I/O Is Accessed by Setting up a Register Located at Certain Addresses in the Memory Map.

• Registers Are Usually 8 Bit Devices Where Each Bit Has a Special Function.

• Analog Inputs Are Sometimes Included on the Microcontroller, but Most of the Time They Are a Function of External Chips Connected to the Microcontroller


Data Communication

• RS-232, RS-422 and RS-485 Are the Most Common Methods of Connecting Embedded Controllers Together.

• RS-232 and RS-422 Are Point to Point

• RS-485 is Multidrop


Data Communication

• The Two Fastest Growing Synchronous Data Communication Systems in Use Today Are the USB and Ethernet Systems.

• One Day They May Take Over From RS-232, RS-422 and RS-485.


Noise Reduction

• Noise Reduction in Electronic Circuits Is Fast Becoming a High Priority in Printed Circuit Board and System Design.

• There Are Two Issues With Respect to Noise Reduction in Controller Systems. One Is Preventing Noise Being Transmitted From the Device

Into the Outside World The Other Is Installing Systems That Are Less Susceptible to

Noise From Outside Sources.


Noise Reduction

• As Electronics on the Printed Circuit Board Becomes Faster and Faster Interference Increases.


Noise Reduction

• PLC’s, DCS’s and Other Control Systems Are Very Susceptible to Noise From External Sources.

• The Most Common Way Noise Gets Inside a Controller Is Through the Wiring in the Cable Run.

• The Wire Connecting the Controller to Sensors, PLCs and Other Equipment Acts Like an Antenna.


Grounding Solutions

• In PCB Design There Are Four Areas of Major Concern

• Placement of Components• Track Placement • Ground Planes • 1D and 3D Faraday Boxes


Grounding Solutions

A Faraday Box on a PCB


Installation Techniques

• Installation of Controllers, Sensors and Wire Systems Is an Important Part of the Overall Quality of a System.

• The Best Designed System Will Fail If the Installation Is Not Done Correctly.

• Proper Installation Is a Very Subjective Thing and There Are Many Standards.

• Most Installers Rely on Their Experience and Personal Training.


Installation Techniques

A Good Installation


Conclusion• It Is Impossible to Cover Every Detail Associated With the Subject of

Embedded Control Systems.

• It Is Hoped That This Workshop Will Give the Delegate Some Hard Hitting Practical Knowledge Concerning the Troubleshooting and Design of Embedded Controllers.

• Although the Delegate May Never Design the Hardware or Software Associated With an Embedded Controller, This Workshop Should Give the Delegate an Overview of the Inter-workings of the Microcontroller.

• As Time Goes on the Microcontroller Will Become an Increasingly Important Part of Our Lives. It Is to This End, That IDC Technologies Hopes the Delegate Will Find This Workshop of Some Benefit.


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Practical Embedded Controllers: Troubleshooting and Design

Engineering

Transcript of Practical Embedded Controllers: Troubleshooting and Design