SENIOR DESIGN

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SENIOR DESIGN

• 10/3

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TERMINOLOGY

• Microcontroller vs. Microprocessor vs.
  Microcomputer
• A microprocessor is a central processing unit on
  a single chip.
• A microprocessor combined with support circuitry
  , peripheral I/O components and memory (RAM
  ROM) used to be called a microcomputer.
• A microprocessor where all the components
  mentioned above are combined on the same single
  chip that the microprocessor is on, is called a
  microcontroller.
• We will be using the ATMEGA 168 microcontroller.

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MICROCONTROLLER ARCHITECTURE
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MICRCONTROLLER ARCHITECTURE

• 1 CPU -- fetches the instructions stored in the
  program memory, decodes them, and executes them.
  The CPU itself is composed of registers the
  arithmetic logic unit, the instruction decoder
  and control circuitry.
• 2 PROGRAM MEMORY The program memory stores the
  instructions that form the program. To
  accommodate larger programs, the program memory
  may be partitioned as internal program memory and
  external program memory (in some controllers).
  Program memory is usually nonvolatile and is of
  EEPROM, EPROM, Flash, or OTP (one-time
  programmable) type. EEPROM for Atmega168.
• 3 RAM The RAM is the data memory of the
  controller. The CPU uses RAM to store variables
  as well as the stack. The stack is used by the
  CPU to store return addresses from where to
  resume execution after it has completed a
  subroutine or an interrupt call.

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MICRCONTROLLER ARCHITECTURE

• 4 CLOCK OSCILLATOR The controller executes the
  program out of the program memory at a certain
  rate. This rate is determined by the frequency of
  the clock oscillator. The clock oscillator could
  be an internal RC-oscillator this is the case
  for the Atmega 168, or an oscillator with an
  external timing element, such as a quartz crystal
  or RC circuit. As soon as power is applied to the
  controller, the oscillator starts operating.
• 5 RESET AND BROWNOUT DETECTOR CIRCUIT The reset
  circuit in the controller ensures that at startup
  all the components and control circuits in the
  controller start at a predefined initial state
  and all the required registers are initialized
  properly.
• The brownout detector is a circuit that monitors
  the power supply voltage, and if there is a
  momentary drop in voltage, resets the processor
  so that the drop in voltage does not corrupt
  register and memory contents, which could lead to
  faulty operations.

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MICRCONTROLLER ARCHITECTURE

• 6 SERIAL PORT The serial port can operate at
  any required data transfer speed. The serial port
  takes data bytes from the controller and shifts
  out the data one bit at a time to the output.
  Similarly, it accepts external data a bit at a
  time, makes a byte out of 8 such bits, and
  presents this to the controller.
• 7 DIGITAL I/O PORT The microcontroller uses the
  digital I/O components to exchange digital data
  with the outside world. Compared to the serial
  port, which transfers data a bit at a time, the
  data from the I/O port is exchanged as bytes.
• 8 ANALOG I/O PORT Analog input is performed
  using an analog-to-digital converter (ADC). The
  controller could be equipped with an integrated
  ADC or an analog comparator the Atmega 8 has
  both (?) , which is used under software control
  to perform A-to-D conversion. ADCs are used to
  acquire sensor data from devices such as
  temperature sensors and photocells. Such sensors
  often produce proportional analog voltage data.
• Analog output is performed using a
  digital-to-analog converter (DAC) must be
  externally in case of Atmega 8.
• Most controllers are equipped with pulse-width
  modulators that can be used to get analog voltage
  with a suitable external RC filter this is the
  case for the Atmega168. DACs are used to drive
  motors, to generate sound, for visual displays..
  (dimming LEDs).
• SENSORS assignment.

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MICRCONTROLLER ARCHITECTURE

• 9 TIMER The timer is used by the controller to
  time events. The timer can also be used as a
  counter.
• 10 WATCHDOG TIMER A watchdog timer (WDT) is a
  special timer with a specific function. It is
  usually used to prevent software crashes. It
  works as follows Once armed, the WDT increments
  an internal counter at some rate. If the user
  program does not reset the counter, the counter
  overflows, which is used to reset the controller.
  .. . The assumption is that if the user program
  does not reset the WDT, it has failed in some way
  and therefore rather than system crash or
  unpredictable system performance, it is better to
  reset the system.
• 11 RTC A real time clock (RTC) is a special
  timer with the task of maintaining time of day,
  date etc.. . It can be used to time-stamp events
  must be externally added to Atmega168.
• -------------------------------------------------
• Like microprocessors, microcontrollers are
  classified as 8-bit, 16-bit, etc.. . This refers
  to the width of the internal registers and the
  accumulator.
• An 8-bit system usually also means that the CPU
  connects to the various chip component through an
  8-bit data path.

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MICRCONTROLLER ARCHITECTURE
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FROM ATMEGA8 Datasheet.
In order to maximize performance and parallelism,
the AVR uses a Harvard architecture with
separate memories and buses for program and data.
Instructions in the Program memory are executed
with a single level pipelining. While one
instruction is being executed, the next
instruction is pre-fetched from the Program
memory. This concept enables instructions to be
executed in every clock cycle. The Program memory
is In- System Reprogrammable Flash memory. The
fast-access Register File contains 32 x 8-bit
general purpose working registers with a single
clock cycle access time. This allows single-cycle
Arithmetic Logic Unit (ALU) operation. In a
typical ALU operation, two operands are output
from the Register File, the operation is
executed, and the result is stored back in the
Register File in one clock cycle.
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Six of the 32 registers can be used as three
16-bit indirect address register pointers
for Data Space addressing enabling efficient
address calculations. One of the these address
pointers can also be used as an address pointer
for look up tables in Flash Program memory. These
added function registers are the 16-bit X-, Y-,
and Z-register, described later in this
section. The ALU supports arithmetic and logic
operations between registers or between a
constant and a register. Single register
operations can also be executed in the ALU.
After an arithmetic operation, the Status
Register is updated to reflect information about
the result of the operation. The Program flow is
provided by conditional and unconditional jump
and call instructions, able to directly address
the whole address space. Most AVR instructions
have a single 16-bit word format. Every Program
memory address contains a 16- or
32-bit instruction. Program Flash memory space is
divided in two sections, the Boot program section
and the Application program section. Both
sections have dedicated Lock Bits for write
and read/write protection. The SPM instruction
that writes into the Application Flash
memory section must reside in the Boot program
section. During interrupts and subroutine calls,
the return address Program Counter (PC) is stored
on the Stack. The Stack is effectively allocated
in the general data SRAM, and consequently the
Stack size is only limited by the total SRAM size
and the usage of the SRAM. All user programs must
initialize the SP in the reset routine (before
subroutines or interrupts are executed). The
Stack Pointer SP is read/write accessible in the
I/O space. The data SRAM can easily be accessed
through the five different addressing modes
supported in the AVR architecture. The memory
spaces in the AVR architecture are all linear and
regular memory maps. A flexible interrupt module
has its control registers in the I/O space with
an additional global interrupt enable bit in the
Status Register. All interrupts have a separate
Interrupt Vector in the Interrupt Vector table.
The interrupts have priority in accordance with
their Interrupt Vector position. The lower the
Interrupt Vector address, the higher the
priority. The I/O memory space contains 64
addresses for CPU peripheral functions as
Control Registers, SPI, and other I/O functions.
The I/O Memory can be accessed directly, or
as the Data Space locations following those of
the Register File, 0x20 - 0x5F.
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ATMEGA 8 FEATURES --- LOOK AT DATASHEET !
High-performance, Low-power AVR 8-bit
Microcontroller Advanced RISC Architecture
130 Powerful Instructions Most Single-clock
Cycle Execution 32 x 8 General Purpose Working
Registers Fully Static Operation Up to 16
MIPS Throughput at 16 MHz On-chip 2-cycle
Multiplier Nonvolatile Program and Data
Memories 8K Bytes of In-System
Self-Programmable Flash Endurance 10,000
Write/Erase Cycles Optional Boot Code Section
with Independent Lock Bits In-System Programming
by On-chip Boot Program True Read-While-Write
Operation 512 Bytes EEPROM Endurance 100,000
Write/Erase Cycles 1K Byte Internal SRAM
Programming Lock for Software Security
Peripheral Features Two 8-bit Timer/Counters
with Separate Prescaler, one Compare Mode One
16-bit Timer/Counter with Separate Prescaler,
Compare Mode, and Capture Mode Real Time
Counter with Separate Oscillator Three PWM
Channels 8-channel ADC in TQFP and MLF
package Eight Channels 10-bit Accuracy
6-channel ADC in PDIP package Eight Channels
10-bit Accuracy Byte-oriented Two-wire Serial
Interface Programmable Serial USART
Master/Slave SPI Serial Interface Programmable
Watchdog Timer with Separate On-chip Oscillator
On-chip Analog Comparator
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ATMEGA 8 FEATURES --- LOOK AT DATASHEET !
Special Microcontroller Features Power-on Reset
and Programmable Brown-out Detection Internal
Calibrated RC Oscillator External and Internal
Interrupt Sources Five Sleep Modes Idle, ADC
Noise Reduction, Power-save, Power-down,
and Standby I/O and Packages 23 Programmable
I/O Lines 28-lead PDIP, 32-lead TQFP, and
32-pad MLF Operating Voltages 2.7 - 5.5V
(ATmega8L) 4.5 - 5.5V (ATmega8) Speed
Grades 0 - 8 MHz (ATmega8L) 0 - 16 MHz
(ATmega8) Power Consumption at 4 Mhz, 3V,
25C Active 3.6 mA Idle Mode 1.0 mA
Power-down Mode 0.5 µA
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ATMEGA 8 PINOUT
DIGITAL PORT AS WELL AS reset RX/TX (serial
communication) RX/TX are internally wired with
FTDI chip (USB to serial) on Arduino. can still
be used, but not at same time that Arduino is
using them.
ANALOG PORT
DIGITAL PORT AS WELL AS Serial Clock
Master/Slave/Slave Select for SPI protocol. (used
to connect external hardware that uses SPI
protocol. Ex external EEPROM).
DIGITAL PORT AS WELL AS oscillators (can be used
to connect external oscillator / crystal
crystal more precise than internal RC
oscillator)
most pins have dual functionality. Some of these
pins are internally wired with the Arduino and
not available for usage.
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ATMEGA8 / ARDUINO INTEGRATION
SERIAL to USB CONVERTER
voltage regulator
SPI
SERIAL to USB CONVERTER
Microcontroller
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ARDUINO INTEGRATION
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ARDUINO

• Digital I/O pin 0-13
• 0-1 internally used for serial communication
  (program Arduino via USB) maybe used for
  external serial communication when not being
  programmed. However, external devices need to be
  disconnected during programming. solution to
  problem use software serial.
• 2-8 general I/O pins. Like all I/O pins,
  these may be defined as either input or output
  pins.
• 9-11 PWM pins. May also be used as standard
  I/O pins.
• 12 general I/O. 13 output pin.
  Internally wired to LED. May be connected to
  other components but must be used as output pin.
• Analog I/O
• 0-6 These pins have the same numbering as the
  digital pins, but are located at a different
  port. A different software function is used in
  order to write to these ports. These pins may be
  used as analog input pins (used for sensors for
  example or for any other variable analog input).
  They can also effectively be used as digital
  input or output pins.
• Power, Ground, AREF
• GND The Arduino provides 3 GND pins. All the
  grounds are internally connected and should be
  connected to the ground of your circuity as well.
  
• 5V When powered through the USB cable or a
  power adaptor, this pin provides 5V. This pin may
  also serve as an input pin for 5V to power the
  board.
• 9V This is an input pin and may be used to
  power the board externally from a battery (for
  example).
• AREF Is used to change the resolution of
  analogue to digital convergence. We won't use
  this function in this workshop. Instead we will
  do the same thing by re-writing the wiring.c
  source file, when using the Ozone sensor. (not
  for CO).
• THE ARDUINO MAY BE POWERED IN 3 DIFFERENT WAYS
  
• 1) Through the USB cable. This is particulary
  handy when programming the device.
• 2) Through and external power supply, using the
  power supply connector on the Arduino board.
  
• 3) Through batteries or external power supply
  using the 5V or 9V pins on the Arduino.

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PINMAPPING
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AVR LIB ARDUINO

• AVR hardware specifically designed to work with
  C-compiler. Pic/ Assembly-yes, AVR/ Assembly
  -good luck )

should be wiring.c
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DICE

• This assignment introduces you to the digital IO
  ports on the Atmega8. You will create a dice game
  using 8 digital pins.
• The game should do the following
• 1) When the game is turned on, each possible
  value (1-6) will be displayed on each die.
• 2) Whenever the button is pressed, the dice will
  "roll" and then display a random value, first die
  one, then on die two.
• Supplies
• 14 leds, 7 each of two different colors
• 10 x 1k ohm resistors
• 1 x 47k ohm resistor
• 1 momentary on pushbutton switch
• 2 x 2n2222 switching transistors
• wire

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DICE

• ASSIGNMENT GOALS
• 1 familiarize yourself with Atmel/Arduino
  environment.
• 2 learn basic Arduino software commands.
• 3 understand Atmel -gt Arduino pin connections.
• 4 describe functionality of a simple circuit.

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This schematic indicates the connections to the
ATMEL, NOT to the Arduino ports. You have to
compare the schematic below to the Arduino
schematic available on our resource site, in
order to complete this assignment.
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http//arduino.cc/en/Tutorial/HomePage
http//arduino.cc/en/Reference/HomePage
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TODAY IN LAB

• Install Arduino software.
• Connect an LED and write an LED blink loop.

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