The Arduino Briefing. The Arduino Briefing

Transcription

1 Mr. Yee Choon Seng csyee@simtech.a-star.edu.sg Design Project resources One-Stop robotics shop A-Main Objectives Pte Ltd, Block 1 Rochor Road, #02-608, Rochor Centre, S180001, Tel: C.S. Yee 1 Layout of ports & connectors on Arduino Leonardo C.S. Yee 2 1

2 Arduino Leonardo Features Microcontroller: ATmega32u4 Operating Voltage: 5V Input Voltage: (recommended) 7-12V (limits) 6-20V Digital I/O Pins 20 PWM Channels 7 Analog Input Channels 12 DC Current per I/O Pin 40 ma (for 3.3V Pin 50 ma) Flash Memory: 32 KB (ATmega32u4, 4 KB bootloader) SRAM 2.5 KB, EEPROM 1 KB (ATmega32u4) Clock Speed: 16 MHz C.S. Yee 3 Arduino Leonardo - I/O configuration Digital I/O There are 20 INPUT/OUTPUT pins altogether 14 are default digital (0 to 13) 6 are designated analog INPUT pins (A0 to A5) Pin function can be configured individually using pinmode pinmode(pin#, IO); Where pin# can be from 0 to 13, I for INPUT, O for OUTPUT. RC Servo Motor pins 6 pins designated for PWM output, namely 3,5,6 9, 10 & 13 All 6 pins are marked with ~ at digital I/O segment. Can be controlled using analogwrite(pin#, value); Value must be between 0 and 255. Can also use Servo Library, through #include <Servo.h> C.S. Yee 4 2

3 Arduino Leonardo - I/O configuration Analog INPUT pins Default onboard pins are A0 to A5 (6 pins) Additional pins on digital pins 4, 6, 8, 9, 10 & 12, named A6 to A11. Reads 0 to 5V in 10 bits, giving value between 0 to 1023 in integer form. Int val = analogread(pin#); Onboard LED Display Already connected to digital output pin 13. Output HIGH to light up LED, LOW to turn off LED. C.S. Yee 5 Programming using Arduino (or Wiring) setup() function void setup( ) // Declaring a void function // Initialisation instructions, runs once only when // starting program from RESET or power-up. loop() function void loop( ) // Declaring a void function // Program instructions, runs over and over again // until power is turned off. C.S. Yee 6 3

4 Declaring functions int square (int n) return (n * n); // return the value of n * n to the calling point. void music() // routine to play some sound in sequence. // No need to return any value or token. C.S. Yee 7 Data Objects int : 16-bit integer number, -32,768 to +32,767 char: 8-bit character or value, 0 to 255, eg x Decimal number : 1234 Hexadecimal : 0x1F (which is decimal 31) Binary : 0b (decimal 31) Expansion of data objects: Arrays, homogeneous list of any type Structure (struct), non-homogeneous group of related data. Operators (Integers only) Arithmetic +, -, *, / Comparison >, <, ==, >=, <= Bitwise arithmetic (OR), & (AND), ^ (XOR), ~ (NOT) Boolean Arithmetic (OR), && (AND),! (NOT) C.S. Yee 8 4

5 Operators for Long Integers Limited to +, -, *, >, <, ==, >= and <= Operators for float Maths & compare +, -, *, /, >, <, ==, >= and <= Some trigonometric, logarithmic and exponential functions (try not to use them.) Expressions Simple maths expression: a = a + 3; is the same as: a += 3; a++; is the same as a += 1; How about ++a? C.S. Yee 9 Control Flow 1 : if else Syntax: if (expression or condition) <statement or list of statements in >; else <alternative statement(s) in >; Example 1: if (i < 10) j = j + i; else PORTA = j; Example 2: if (i < 10) i++; C.S. Yee 10 5

6 Control Flow 2 : while Syntax: while ( expression or condition ) <statement(s)>; Example: while ( i < 10) i = i + 1; or while (i < 10) i++; C.S. Yee 11 Control Flow 3 : for loop Syntax: for ( <expr-1>, <expr-2>, <expr-3>) <statement(s)>; <expr-1> : assignment / initial condition <expr-2> : relational expression <expr-3> : increment / decrement steps Example: for (i=0; i<10; i++) PORTA = i; or for (i=0; i<10; i++) PORTA = i; C.S. Yee 12 6

7 Control Flow 4: switch Syntax: switch( variable) Case value1: // Do this if variable has value1 break; Case value2: // Do this if variable has value2 break; // And so on, until the last known case value. default: // Do this if doesn t fit any of the above cases. break; C.S. Yee 13 Control Flow 5 : break The break statement is used to get out of the while, for and switch loop without finishing the full number of cycles. Preprocessor Pre-conditions for the compiler before creating executable program for the MicroController. Declaring constants: #define PI #define FORWARD 0 #define BACKWARD 1 Adding header files: #include <Servo.h> C.S. Yee 14 7

8 Useful Standard Arduino functions pinmode(pin#, IO); // Configures digital pin to Input or Output pin# is digital pin number IO can be I for INPUT or O for OUTPUT Normally placed in setup(). int val = digitalread(pin#); pin# is digital pin number value should be 0 or 1. // Read from Digital input pin digitalwrite(pin#, value); // Write to Digital output pin. pin# is digital pin number value can be 0 or 1, LOW or HIGH int val = analogread(pin#); // Read from Analog input pin pin# is analog Input pin number value will be from 0 to 1023 (corresponding to 0 to 5V analog input) C.S. Yee 15 Useful Standard Arduino functions analogwrite(pin#, value); // Write to control PWM output pin# is digital pin number of PWM pin value can be from 0 (for 0% duty cycle) to 255 (100% duty cycle) delay(value); // delay in milliseconds value can be 0 to 32767, in ms. delaymicroseconds(value); // delay in microseconds value can be in LONG format, UL int val = min(x, y); int val = max(x, y); int val = abs(x, y); // Returns smaller value // Returns bigger value // Returns absolute value, only positive C.S. Yee 16 8

9 Servo Library for RC Servo Motors #include <Servo.h> Routines attach() Attach the Servo variable to a pin. write() Writes a value to the servo, controlling the shaft accordingly. (0 to 180, 90 being the neutral position.) writemicroseconds() Writes a value in microseconds (us) to the servo, controlling the shaft accordingly. (typically 1000 to 2000, 1500 being the neutral position.) read() Read the current angle of the servo. (0 to 180) attached() Check whether the Servo variable is attached to a pin. detach() Detach the Servo variable from its pin. C.S. Yee 17 Servo Library Sample #include <Servo.h> Servo myservo; void setup() myservo.attach(9); // Attach servo to pin 9 myservo.write(90); // set servo to mid-point void loop() // Main part of the program C.S. Yee 18 9

10 Arduino Resources // Arduino Home Page This is the Arduino Home page, where Arduino related information can be found. The latest Arduino Software can also be downloaded here, and it is freeware. Tutorials and references to the programming or Arduino boards can be found under Learning. Join the Forum under Support to mingle with other Arduino experimenters to discuss problems and search for solutions, or sample programs. Don t trust everything you read, but try them out yourselves!! You may download the essential tutorial, reference and software files from From 11 January 2014 onwards. C.S. Yee 19 10