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FLOW CHART PROGRAMMINGFOR AVR MICROCONTROLLERSUSING FLOWCODEPREPARED BY: TIRSO LLANTADA, ECE
TOPIC TO BE DISCUSSED
• MICROCONTROLLERS
• AVR MICROCONTROLLERS
• FLOW CHART
• FLOWCODE
MICROCONTROLLERS
General Purpose
Microprocessor
RAM ROM TimerSerialCOMPort
IO Port
Data BUS
Address BUS
Control BUS
CPU RAM ROM
I/OTimerSerialPort
• General Purpose Microprocessors
• Microcontrollers
EMBEDDED SYSTEMS
EMBEDDED SYSTEMS
COMMON MICROCONTROLLERS
MICROCONTROLLER ARCHITECTURE
TOPIC TO BE DISCUSSED
• MICROCONTROLLERS
• AVR MICROCONTROLLERS
• FLOW CHART
• FLOWCODE
AVR MICROCONTROLLERS
• The acronym AVR has been reported to stand for: Advanced Virtual RISC and also for the chip's designers: Alf-Egil Bogen and Vegard Wollan who designed the basic architecture at the Norwegian Institute of Technology.
• RISC stands for reduced instruction set computer.
CPU design with a reduced instruction set as well as a simpler set of instructions (like for example PIC and AVR)
A LITTLE HISTORY
• The PIC (Programmable Interrupt Controller) appeared around 1980.
→ 8 bit bus
→ executes 1 instruction in 4 clk cycles
→ Harvard architecture
• AVR (1994)
→ 8 bit bus
→ one instruction per cycle
→ Harvard architecture
AVR INTERNAL ARCHITECTURE
PROGRAM ROM
PortsOSC
CPU
Timers
OtherPeripherals
ProgramBus Bus
RAM
I/O PINS
EEPROM
Interrupt Unit
AVR DIFFERENT GROUPS
• Classic AVR
• e.g. AT90S2313, AT90S4433
• Mega
• e.g. ATmega8, ATmega32, ATmega128
• Tiny
• e.g. ATtiny13, ATtiny25
• Special Purpose AVR
• e.g. AT90PWM216,AT90USB1287
LET’S GET FAMILIAR WITH THE AVR PART NUMBERS
ATmega128
ATtiny44
Atmel group Flash =128K
AtmelFlash =4K
AT90S4433
Atmel Classic group
Flash =4KTiny group
AVR’S CPU
• AVR’s CPU
• ALU
• 32 General Purpose registers (R0 to R31)
• PC register
• Instruction decoder CPUPC
ALU
registers
R1
R0
R15
R2
…
R16
R17
…
R30
R31
Instruction Register
Instruction decoder
SREG: I T H S V N CZ
TOPIC TO BE DISCUSSED
• MICROCONTROLLERS
• AVR MICROCONTROLLERS
• FLOW CHART
• FLOWCODE
FLOWCHART
• A flowchart is a diagram that depicts the “flow” of a program.
START
Display message “How many hours did you work?”
Read Hours
Display message “How much do you get paid per hour?”
Read Pay Rate
Multiply Hours by Pay Rate. Store result in Gross Pay.
Display Gross Pay
END
ALGORITHMS AND FLOWCHARTS
• A typical programming task can be divided into two phases:
• Problem solving phase
• produce an ordered sequence of steps that describe solution of problem
• this sequence of steps is called an ALGORITHM
• Implementation phase
• implement the program in some programming language
Rounded Rectangle
Parallelogram
Rectangle
Rounded Rectangle
START
Display message “How many hours did you work?”
Read Hours
Display message “How much do you get paid per hour?”
Read Pay Rate
Multiply Hours by Pay Rate. Store result in Gross Pay.
Display Gross Pay
END
BASIC FLOWCHART SYMBOLS
BASIC FLOWCHART SYMBOLS
• Terminals
• represented by rounded rectangles
• indicate a starting or ending point
Terminal
START
ENDTerminal
START
Display message “How many hours did you work?”
Read Hours
Display message “How much do you get paid per
hour?”
Read Pay Rate
Multiply Hours by Pay Rate. Store result in Gross
Pay.
Display Gross Pay
END
BASIC FLOWCHART SYMBOLS
• Input/Output Operations
• represented by parallelograms
• indicate an input or output operation
Display message “How many
hours did you work?”
Read Hours
Input/Output Operation
START
Display message “How many hours did you work?”
Read Hours
Display message “How much do you get paid per
hour?”
Read Pay Rate
Multiply Hours by Pay Rate. Store result in Gross
Pay.
Display Gross Pay
END
BASIC FLOWCHART SYMBOLS
• Processes
• represented by rectangles
• indicates a process such as a mathematical computation or variable assignment
Multiply Hours by Pay Rate. Store
result in Gross Pay.
Process
START
Display message “How many hours did you work?”
Read Hours
Display message “How much do you get paid per
hour?”
Read Pay Rate
Multiply Hours by Pay Rate. Store result in Gross
Pay.
Display Gross Pay
END
FOUR FLOWCHART STRUCTURES
• Sequence
• Decision
• Repetition
• Case
SEQUENCE STRUCTURE
• a series of actions are performed in sequence
• The pay-calculating example was a sequence flowchart.
DECISION STRUCTURE
• One of two possible actions is taken, depending on a condition.
DECISION STRUCTURE
• A new symbol, the diamond, indicates a yes/no question. If the answer to the question is yes, the flow follows one path. If the answer is no, the flow follows another path
YESNO
DECISION STRUCTURE
• In the flowchart segment below, the question “is x < y?” is asked. If the answer is no, then process A is performed. If the answer is yes, then process B is performed.
YESNOx < y?
Process BProcess A
DECISION STRUCTURE
• The flowchart segment below shows how a decision structure is expressed in C++ as an if/else statement.
YESNOx < y?
Calculate a as x times 2.
Calculate a as x plus y.
if (x < y)
a = x * 2;
else
a = x + y;
Flowchart C++ Code
DECISION STRUCTURE
• The flowchart segment below shows a decision structure with only one action to perform. It is expressed as an if statement in C++ code.
if (x < y)
a = x * 2;
Flowchart C++ Code
YESNOx < y?
Calculate a as x times 2.
REPETITION STRUCTURE
• A repetition structure represents part of the program that repeats. This type of structure is commonly known as a loop.
REPETITION STRUCTURE
• Notice the use of the diamond symbol. A loop tests a condition, and if the condition exists, it performs an action. Then it tests the condition again. If the condition still exists, the action is repeated. This continues until the condition no longer exists.
REPETITION STRUCTURE
• In the flowchart segment, the question “is x < y?” is asked. If the answer is yes, then Process A is performed. The question “is x < y?” is asked again. Process A is repeated as long as x is less than y. When x is no longer less than y, the repetition stops and the structure is exited.
x < y?
Process A
YES
REPETITION STRUCTURE
• The flowchart segment below shows a repetition structure expressed in C++ as a while loop.
while (x < y)
x++;
FlowchartC++ Code
x < y?
Add 1 to x
YES
CONTROLLING A REPETITION STRUCTURE
• The action performed by a repetition structure must eventually cause the loop to terminate. Otherwise, an infinite loop is created.
• In this flowchart segment, x is never changed. Once the loop starts, it will never end.
• QUESTION: How can thisflowchart be modified soit is no longer an infiniteloop?
x < y? Display x
YES
CONTROLLING A REPETITION STRUCTURE
• ANSWER: By adding an action within the repetition that changes the value of x.
x < y? Display x
Add 1 to x
YES
A PRE-TEST REPETITION STRUCTURE
• This type of structure is known as a pre-test repetition structure. The condition is tested BEFORE any actions are performed.
x < y? Display x
Add 1 to x
YES
A PRE-TEST REPETITION STRUCTURE
• In a pre-test repetition structure, if the condition does not exist, the loop will never begin.
x < y? Display x
Add 1 to x
YES
A POST-TEST REPETITION STRUCTURE
• This flowchart segment shows a post-testrepetition structure.
• The condition is tested AFTER the actionsare performed.
• A post-test repetition structure alwaysperforms its actions at least once.
Display x
Add 1 to x
YESx < y?
A POST-TEST REPETITION STRUCTURE
• The flowchart segment below shows a post-test repetition structure expressed in C++ as a do-while loop.
do{
cout << x << endl;x++;
} while (x < y);
Flowchart
C++ Code
Display x
Add 1 to x
YESx < y?
CASE STRUCTURE
• One of several possible actions is taken, depending on the contents of a variable.
CASE STRUCTURE
• The structure below indicates actions to perform depending on the value in years_employed.
CASEyears_employed
1 2 3 Other
bonus = 100
bonus = 200
bonus = 400
bonus = 800
CASEyears_employed
1 2 3 Other
bonus = 100 bonus = 200 bonus = 400 bonus = 800
If years_employed = 1, bonus is set to 100
If years_employed = 2, bonus is set to 200
If years_employed = 3, bonus is set to 400
If years_employed is any other value, bonus is set to 800
CASE STRUCTURE
CONNECTORS
• Sometimes a flowchart will not fit on one page.
• A connector (represented by a small circle) allows you to connect two flowchart segments.
A
A
A
START
END
•The “A” connector indicates that the second flowchart segment begins where the first segment ends.
CONNECTORS
MODULES
• A program module (such as a function in C++) is represented by a special symbol.
•The position of the module symbol indicates the point the module is executed.
•A separate flowchart can be constructed for the module.
START
END
Read Input.
Call calc_pay function.
Display results.
MODULES
COMBINING STRUCTURES
• Structures are commonly combined to create more complex algorithms.
• The flowchart segment below combines a decision structure with a sequence structure.
x < y? Display x
Add 1 to x
YES
COMBINING STRUCTURES
• This flowchart segment shows two decision structures combined.
Display “x is within limits.”
Display “x is outside the
limits.”
YESNOx > min?
x < max?
YES NO
Display “x is outside the
limits.”
EXAMPLE 1
• Draw flowchart to creates a table for the two-variable equation X =3Y by calculating and printing the value of X for each positive-integer value of Y.
EXAMPLE 2
A program is required to read three numbers, add them together and print their total.
Input Processing Output
Number1Number2Number3
Read three numbersAdd number togetherPrint total number
total
Add numbers to total
ReadNumber1Number2number3
Print total
Start
Stop
EXAMPLE 3
• A program is required to prompt the terminal operator for the maximum and minimum temperature readings on a particular day, accept those readings as integers, and calculate and display to the screen the average temperature, calculated by (maximum temperature + minimum temperature)/2.
Input Processing Output
Max_tempMin_temp
Prompt for temperaturesGet temperaturesCalculate average temperatureDisplay average temperature
Avg_temp
EXAMPLE 4
• Design an algorithm that will prompt a terminal operator for three characters, accept those characters as input, sort them into ascending sequence and output them to the screen.
Input Processing Output
Char_1Char_2Char_3
Prompt for charactersAccept three charactersSort three charactersOutput three characters
Char_1Char_2Char_3
EXAMPLE 5
• Design a program that will prompt for and receive 18 examination scores from a mathematics test, compute the class average, and display all the scores and the class average to the screen.
Input Processing Output
18 exam scores
Prompt the scoresGet scoresCompute class averageDisplay scoresDisplay class average
18 exam scoresClass_average
Start
Total_score = zero
I = 1
Add scores(I) to
Total score
I = I + 1
Calculate average
I = I + 1
Prompt and get
Scores (I)
I = 1
I <= 18 ?
DisplayScores (I)
I <= 18 ?
Displayaverage
Stop
T
F
T
F
FLOWCODE
• Flowcode is one of the World’s most advanced graphical programming languages for microcontrollers. The great advantage of Flowcode is that it allows those with little experience to create complex electronic systems. Flowcode is available in twenty languages and supports a wide range of devices. Separate versions are available for the PICmicro (8-bit), AVR/Arduino, dsPIC/PIC24 and ARM series of microcontrollers. Flowcode can be used with many microcontroller development hardware solutions including those from Matrix such as Formula Flowcode, E-blocks, MIAC and ECIO.
ADVANTAGES
• Save time and money Flowcode facilitates the rapid design of electronic systems based of microcontrollers.
• Easy to use interface Simply drag and drop icons on-screen to create an electronic system without writing traditional code line
by line.
• Fast and flexible Flowcode has a host of high level component subroutines which means rapid system development. The
flowchart programming method allows to develop microcontroller programs.
• Error free results Flowcode works. What you design and simulate on-screen is the result you get when you download to your
microcontroller.
• Open architecture Flowcode allows you to view C and ASM code for all programs created and customise them. Access circuit
diagram equivalents to the system you design through our data sheets and support material.
• Fully supported Flowcode is supported by a wide range of materials and books for learning about, and developing, electronic
systems.
• Core-independent Flowcode programs developed for one microcontrollers easily transfer to another microcontroller.
FEATURES
• Supported microcontrollers Microchip PIC 10, 12, 16, 18, dsPIC, PIC24, Atmel AVR/Arduino, Atmel ARM.
• Supported communication systems Bluetooth, CAN, FAT, GPS, GSM, I2C, IrDA, LIN, MIDI, One wire, RC5, RF, RFID, RS232, RS485, SPI, TCP/IP, USB, Wireless LAN, ZigBee
• Supported components ADC, LEDs, switches, keypads, LCDs, Graphical colour LCD, Graphical mono LCDs, Sensors, 7-segment displays, Internal EEPROM, comms systems, Touchscreen LCD, Webserver.
• Supported mechatronics Accelerometer, PWM, Servo, Stepper, Speech.
• Supported subsystems MIAC, MIAC expansion modules, Formula Flowcode.
• Panel designer Design a panel of your choice on-screen and simulate it.
• In-Circuit Debug (ICD) When used with EB006 PIC Multiprogrammer, EB064 dsPIC/PIC24 Multiprogrammer or FlowKit.
• Tight integration with E-blocks Each comms system is supported by E-blocks hardware.
• Virtual networks Co-simulation of many instances of Flowcode for multi-chip systems. Co-simulation of MIAC based systems with MIAC expansion modules.
DESIGN PROCESS
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