Cygni konsulentmøde der handler om arduino robot programmering. I dette tilfælde en line follower robot.

1. VS code can be used as an IDE for programming Arduinos but its a bit of a hassle to setup: guide
2. But, arduino have their own IDE that can be found here

All arduino sketches (programs) are created using .ino file. This will be the entry point for the program. As the arduino is programmed using a version of c++. Therefore packages containing header and implementation files can be used. These files needs to be located in a folder called src.

file structure:

- sketch
    - src
        - class.h
        - class.cpp
    - myFirstSketch.ino

I/O pins Pins are used as the interface for all i/o operations. It is common de use a macro to define a pin.

#define LED_PIN 2 //Macro, now LED_PIN will always have the value 2

Arduino also requires a pin to have a mode (pinMode)

void setup(){
    pinMode(LED_PIN, OUTPUT);   //This sets the LED_PIN's mode to be an output, meaning the pin can send data/voltage out.

    pinMode(SENSOR_PIN, INPUT); //This sets the SENSOR_PINS's mode to be an input, meaning the pin is ready to read data/voltage.
}

There are two types of pins analog and digital pins. Analog pins can read a value between 0 and 1023 where digital pins can only read HIGH or LOW. Some digital pins can output a PWM (pulse width modulation) signal with a range from 0 - 255.

void loop(){
    bool sensor_value = digitalRead(SENSOR_PIN); //This will read the SENSOR_PIN and get a value of either HIGH or LOW
    
    int sensor_value = analogRead(SENSOR_PIN); //This will read the SENSOR_PIN and get a value from 0 - 1023

    digitalWrite(LED_PIN, HIGH) //This will set the LED_PIN to high (1023)

    analogWrite(LED_PIN, 127) //This will set the LED_PIN to a value of 127 (1)
}

(1) Because the max value is 255 and 127 is half of that, the pulse width modulation will only send a voltage half the time, resulting in the LED being lit with half intesity.

Because the execution of the code is triggered in a loop, variables that needs to be saved between loops needs to be global. This is done simply by placing the variable outside the loop() and setup() functions.

int counter = 0;

void loop(){
    counter++;
}

Serial printing is a way to send messages over the USB port to the terminal on your pc. Serial communication uses a BAUD rate usually it is set to 9600 if the data that is being send is small. Different boards can also communicate together using Serial communication, but that is a bit more advanced.

void setup(){
    Serial.begin(9600); //This sets the serial communication with a baud rate of 9600

}

void loop(){
    Serial.print("HELLO "); //This prints "HELLO " to the terminal
    Serial.println("WORLD"); //This prints "WORLD" to the terminal and adds a new line flag.
}

An arduino has an internal clock that starts running when the arduino starts. It counts in milliseconds. The clock can be accesed using millis()

unsigned long time_since_start = 0;
void loop(){
    time_since_start = millis();
}