innovation fellows program - lectures & resources · with the standard arduino libraries,...

Innovation Fellows Program

Arduino Uno Microcontroller Overview Prof. Steven S. Saliterman, http://saliterman.umn.edu/ Department of Biomedical Engineering, University of Minnesota

Prof. Steven S. Saliterman

Arduino Uno


Power & Interface…

USB Interface

Digital I/O Pins Reset Button

ATMega Microcontroller

ICSP Connector

Power & Auxiliary Pins Analog –to - Digital Converter Pins

Debug LED

7 to 12 VDC Input


USB Connection to Computer…


Example Modules – Sensors…

Ultrasonic Sensor - HC-SR04 IR Sensor 2Y0A21 Sharp Digital Distance Sensor

MAX6675 Module + K Type Thermocouple Temperature Sensor

Diymall Bme280 Pressure Temperature Sensor Module with IIC I2c

SunFounder Accelerometer ADXL335


9-Axis Absolute Orientation Sensor…

Absolute Orientation (Euler Vector, 100Hz) Three axis orientation data based on a 360° sphere.

Absolute Orientation (Quaterion, 100Hz) Four point quaternion output for more accurate data manipulation.

Angular Velocity Vector (100Hz) Three axis of 'rotation speed' in rad/s.

Acceleration Vector (100Hz) Three axis of acceleration (gravity + linear motion) in m/s^2.

Magnetic Field Strength Vector (20Hz) Three axis of magnetic field sensing in micro Tesla (uT).

Linear Acceleration Vector (100Hz) Three axis of linear acceleration data (acceleration minus gravity) in m/s^2.

Gravity Vector (100Hz) Three axis of gravitational acceleration (minus any movement) in m/s^2.

Temperature (1Hz) Ambient temperature in degrees celsius.

Courtesy of Adafruit

Sensor “fusion” combines the following measurements…


Actuators…

2-Channel 5 V Solid State Relay Module

Standard Size - High Torque - Metal Gear Servo Stepper Motor

DC Motor with Gear

https://cdn-shop.adafruit.com/1200x900/858-04.jpg

https://cdn-shop.adafruit.com/1200x900/2941-00.jpg


User Interface…

Adafruit 1.8” Color TFT LCD Display with MicroSD Card Breakout – ST77 35R1.8" Color TFT LCD display with MicroSD Card Breakout - ST7735R

7-Segment Serial Display - Red

Diymall 0.96" Inch I2c IIC Serial 128x64 Oled LCD LED White Display Module

Mini ISD2548 Digital Voice Recorder


Consider this Device Concept Task: Make a digital thermometer consisting of an enclosure, microcontroller board, thermocouple sensor, digital display, sound alert, slide switch, pushbutton and battery….

http://store-usa.arduino http://www.globalsources.com http://www.thermometricscorp.com

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwiG-JiLuYLMAhVIVT4KHRRRAR4QjRwIBw&url=http://www.slideshare.net/ns1047/thermocouple-as-a-transducer&psig=AFQjCNEieGBIPttRorWjRYDlbq7xf1NdMg&ust=1460321795910095


Formulate an Algorithm…

1. When the pushbutton is pressed… Measure the temperature, Beep when the reading is good, Display the value for ten seconds, and finally Save the value to memory.

2. Start all over again. 3. Now flowchart this…


Flowchart the Algorithm…

Display Temperature

& Beep

Start

Delay 10 Sec.

Monitor for Button Press

Button Pressed

?

Read Temperature

Valid Reading

?

Clear Display

Store Value

Stop

No

Yes

Yes

No


Software & Programming

1. Software is the smart in your “smart device.” 2. An algorithm displayed as a flowchart, transforms your problem

into various input, processing, decision and output steps 3. Lines of code are written to implement your algorithm. 4. Code may be written in assembly language and/or higher level

languages such as C, C++, and C#. 5. A compiler converts your code into machine language that the

microcontroller understands. 6. The compiled code is then uploaded into a board containing the

microcontroller, memory and various interface circuits. 7. Errors are then fixed by debugging. 8. You may write your own code and/or incorporate code that has

been written by others (“sketches”).


Integrated Development Environment (IDE)

Editor – To write your code in C (.c) and/or assembly (.a) language. A finished program is called a “sketch.”

Compiler – Turns your code into machine readable instructions or object files (.o). A Linker combines this code with the standard Arduino Libraries, producing a single hex file (.h).

Means to Upload – Transferring the hex file to the Arduino board program memory. This is done via the USB or serial connection with the aid of the bootloader.

Means to Run – Executing the Program Means to Debug – Finding & Correcting Errors


1. Structures A. Setup & loop B. Control statements C. Syntax D. Arithmetic operators E. Comparison operators F. Bitwise operators G. Compound operators

Arduino Programming Components

2. Variables A. Constants B. Data Types C. Variable Scope D. Qualifiers E. Conversion F. Utilities

3. Functions A. Digital I/O B. Analog I/O C. Due & Zero only D. Advanced I/O E. Time F. Math G. Trigonometry H. Characters I. Random numbers J. Bits and bytes K. External interrupts L. Interrupts M. Communication N. USB

We will discuss today only the items above in blue.


1. Structures: Setup() Example

1) Initialize variables

2) Assign pins 3) Runs once, after

powerup or reset.

int buttonPin = 3; void setup() { Serial.begin(9600) ; //serial baud rate pinMode(buttonPin), INPUT); //assign pin 3 to be an input } void loop() { … }


Loop() Example

1. Occurs after setup.

2. Loops consecutively

3. Initialize variables 4. Assign pins 5. Runs once, after

powerup or reset. 6. Variations: if, if-

else; if-else-if

int buttonPin = 3; void setup() { Serial.begin(9600) ; //serial baud rate pinMode(buttonPin), INPUT); //assign 3 to be an input } void loop() { if(digitalRead(buttonPin) == HIGH) Serial.write(‘H’); else serial.write(‘L’); delay(1000); }


Control Statements

Loop Statements For While Do-While

Decision Statements Break and Continue If If-Else, if-else-if Switch-Case

Directional Goto Return


Arrays…

1. The first element is indexed with zero, e.g. a[3] has 3 elements, a[0], a[1], and a[2].

2. Declare as usual, e.g. int a[3], float a[3], and char a[3]. 3. Initialize: int a[3] = {2, 6, 1}. 4. Ok to initialize using a “for” loop. 5. If number of elements is not stated, the initialization will

determine it, e.g. int a[ ] = {2, 6, 1} – elements will be three. 6. Arrays may be multidimensional, e.g. a[3, 5]. 7. Two dimensional (rows and columns) can also be written, e.g.

int M[4] [5] (remember there is a zero row and column). 8. Number of elements may be determined by variable – in which

case range check first.


“For” Statement (a Loop)…

for (initialization; condition; increment) {program statement(s);} Example – What is the value of the a[49] element? … int a[100]; for (int n = 0; n < 100; n = n + 1) { a[n] = n * 2; } …

Statement Format

Example Code


“While” Statement (a Loop)…

while (expression – a boolean that is true or false) {program statement(s);} Example – What is the value of a[30] element? … int a[100]; int n = 0; while (n < 100) { a[n] = n * 3; n = n + 1; // Could also use “++n” } …


“Do-while” Statement (a Loop)…

do {program statement(s)} while (test condition); Example – What is the value of a[75] element? … int a[100]; int n = 0; do { a[n] = n * 4; n = n + 1; } while n < 100; …


“If” Statement (a Decision)…

if (expression) {program statement(s);} Example – What is the value of n? … int a = 4, n = 0; if a <= 5 { n = n + 50; } …


“If-Else” Statement (a Decision)…

if (expression) {program statement(s);} else {program statement(s)}; Example – What is the value of n? … int a = 10, n = 0; if a <= 5 { n = n + 50; } else { n = n + 25; } …


“Switch – Case” Statement (a Decision…)

switch (expression) { case label1: program statements; break; case label2: program statements; break; default: program statements; break; }

For example: int a; Bool buy; … a = 2; switch (a) { case 1: // if a =1 buy = true; break; case 2: // if a =2 buy = false; break; } …


Syntax

; Used to end a statement { } Enclose statements, keep balanced // Start comment until end of line /* … */ Multi-line comment

#define Assigning a value to a constant name Follows C rules and no semicolon afterwards Use const type variable = value (e.g. const float pi = 3.14) when able instead.

#include To include outside libraries


Arithmetic & Boolean Operators

= assignment operator + addition - subtraction * multiplication / division % modulo

&& and || or ! not


Comparison & Pointer Operators

== equal to != not equal to < less than > greater than <= less than or equal to >= greater than or equal to

* dereference & reference


2. Variables: Constants

1. true | false (typed in lower case) 1. false is defined as zero 2. true is defined as one, or any boolean test of an

integer that is non-zero. 2. Integer constants:

Decimal 123 Binary B11110000 (leading B) Octal 0173 (leading zero) Hexadecimal 0x7B (leading 0x)


5. Floating point constants: Constant Evaluates to Also 10.0 10 2.34E5 2.34 * 10^5 234000 67e-5 67.0 * 10^-5 .00067


Data Types

1. boolean (8 bit) - simple logical true/false (1 byte = 8 bits) 2. byte (8 bit) - unsigned number from 0-255 3. char (8 bit) - signed number from -128 to 127. The compiler

will attempt to interpret this data type as a character in some circumstances, which may yield unexpected results

https://learn.sparkfun.com/tutorials/data-types-in-arduino

4. unsigned char (8 bit) - same as ‘byte’; if this is what you’re after, you should use ‘byte’ instead, for reasons of clarity

5. word (16 bit) - unsigned number from 0-65535 (1 word = 2 bytes)

6. unsigned int (16 bit)- the same as ‘word’. Use ‘word’ instead for clarity and brevity.


9. long (32 bit) - signed number from -2,147,483,648 to 2,147,483,647

10. float (32 bit) or double- signed number from -3.4028235E38 to 3.4028235E38. Floating point on the Arduino is not native; the compiler has to jump through hoops to make it work. If you can avoid it, you should.

https://learn.sparkfun.com/tutorials/data-types-in-arduino

7. int (16 bit) - signed number from -32768 to 32767. This is most commonly what you see used for general purpose variables in Arduino example code provided with the IDE.

8. unsigned long (32 bit) - unsigned number from 0-4,294,967,295. The most common usage of this is to store the result of the millis() function, which returns the number of milliseconds the current code has been running.


Variable Scope

1. A global variable is one that can be seen by every function in a program. Local variables are only visible to the function in

which they are declared. In the Arduino environment, any variable declared

outside of a function (e.g. setup(), loop(), etc. ), is a global variable.

“For “ loop variables are local. 2. Static - the static keyword is used to create

variables that are visible to only one function.


3. Functions: Digital I/O (Digital Pins)

Digital pins on the Arduino can be defined as being Inputs or Outputs using the function pinMode().

The state of a digital pin can be determined with the function digitalRead().

The state of an output can be set as High or Low with the function digitalWrite().


digitalWrite()

digitalWrite() writes a HIGH or a LOW value to a digital pin. If the pin has been configured as an OUTPUT with pinMode(),

its voltage will be set to the corresponding value: 5V (or 3.3V on 3.3V boards) for HIGH, 0V (ground) for LOW.

If the pin is configured as an INPUT, digitalWrite() will enable (HIGH) or disable (LOW) the internal pullup on the input pin. It is recommended to set the pinMode() to INPUT_PULLUP to enable the internal pull-up resistor. See the digital pins tutorial for more information. e.g. digitalWrite(ledPin, HIGH)


digitalRead()

digital read() reads the value from a specified digital pin, either HIGH or LOW.

e.g. digitalRead(inPin);


Example: Blinking an LED const int LED = 10; int blinks = 5; // blink 5 times; bool done = false; void setup() { pinMode(LED, OUTPUT); //set pin 10 as an OUTPUT digitalWrite(LED, LOW); // Initialize off } void loop() { while (done != true) { for (int i = 1; i<= blinks; ++i) // ++i same as i = i+1 { digitalWrite(LED, HIGH); // Turn on LED delay(500); //Pause digitalWrite(LED, LOW); // Turn off LED delay(500); //Pause } done = true; } }


Schematic…


Example: Debouncing a Pushbutton const int LED = 9, BUTTON = 2; bool lastState = LOW, currentState = LOW, lit = false; void setup() { pinMode(LED, OUTPUT); pinMode(BUTTON, INPUT); } boolean debounce(boolean last) //function { boolean state = digitalRead(BUTTON); if(last != state) // has button settled down { delay(5); //delay if not state= digitalRead(BUTTON); //and read again } return state; }

void loop() { currentState = debounce(lastState); //call function if (lastState == LOW && currentState == HIGH) { lit = !lit; //toggle LED } lastState = currentState; digitalWrite(LED, lit); //update LED }


Debouncing a Pushbutton…


analogReference()

analogReference() - configures the reference voltage used for analog input (i.e. the value used as the top of the input range). The options are: DEFAULT: the default analog reference of 5 volts (on 5V

Arduino boards) or 3.3 volts (on 3.3V Arduino boards) INTERNAL: an built-in reference, equal to 1.1 volts on the

ATmega168 or ATmega328 and 2.56 volts on the ATmega8 (not available on the Arduino Mega)

INTERNAL1V1: a built-in 1.1V reference (Arduino Mega only) INTERNAL2V56: a built-in 2.56V reference (Arduino Mega

only) EXTERNAL: the voltage applied to the AREF pin (0 to 5V

only) is used as the reference.


analogRead()

analogRead() reads the value from the specified analog pin. The Arduino board contains a 6 channel (8 channels on the Mini

and Nano, 16 on the Mega), 10-bit analog to digital converter. This means that it will map input voltages between 0 and 5 volts into integer values between 0 and 1023. This yields a resolution between readings of: 5 volts / 1024 units or, .0049 volts (4.9 mV) per unit. The input range and resolution can be changed using analogReference().

It takes about 100 microseconds (0.0001 s) to read an analog input, so the maximum reading rate is about 10,000 times a second


analogWrite()

analogWrite() writes an analog value (PWM wave) to a pin.

Can be used to light a LED at varying brightnesses or drive a motor at various speeds. After a call to analogWrite(), the pin will generate a steady square wave of the specified duty cycle until the next call to analogWrite() (or a call to digitalRead() or digitalWrite() on the same pin).

The frequency of the PWM signal on most pins is approximately 490 Hz. On the Uno and similar boards, pins 5 and 6 have a frequency of approximately 980 Hz. Pins 3 and 11 on the Leonardo also run at 980 Hz.


analogReadResolution()

analogReadResolution() is also an extension of the Analog API for the Arduino Due and Zero.

Sets the size (in bits) of the value returned by analogRead(). It defaults to 10 bits (returns values between 0-1023) for backward compatibility with AVR based boards.

The Due and the Zero have 12-bit ADC capabilities that can be accessed by changing the resolution to 12. This will return values from analogRead() between 0 and 4095.


Example: Reading a Potentiometer

Igoe, Tom. If statement tutorial. Arduino 2012


const int analogPin = A0; const int ledPin = 13; const int threshold = 400; void setup() { pinMode(ledPin, OUTPUT); Serial.begin(9600); } void loop() { int analogValue = analogRead(analogPin); if (analogValue > threshold) { digitalWrite(ledPin, HIGH); } else { digitalWrite(ledPin, LOW); } Serial.println(analogValue); delay(1); }

Reading a Potentiometer…

Igoe, Tom. If statement tutorial. Arduino 2012

// pin that the potentiometer is attached to // pin that the LED is attached to on UNO // an arbitrary threshold level that's in the range of the analog input // initialize the LED pin as an output // initialize serial communications // read the value of the potentiometer // if the analog value is high enough, turn on the LED // print the analog value // delay in between reads for stability


I2C or “Inter-Integrated Circuit” Serial Interface

SDA SCL Only two bus lines are required; a serial data line (SDA) and a serial clock line

(SCL). Each device connected to the bus is software addressable. Serial, 8-bit oriented, bidirectional data transfers can be made.


Summary

Arduino Uno, sensors and actuator examples. Using an IDE, programs are typically written in C and assembly

language, compiled, linked with libraries and uploaded onto the Arduino board memory as hexadecimal code.

Structures, variables and functions comprise an embedded program.

Digital pins are defined as INPUT or OUTPUT and having levels of HIGH and LOW.

Digital and analog functions. Examples: blinking light, debouncing a pushbutton and reading a

potentiometer. I2C Serial Interface.

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